Download IWMO-2016 8th International Workshop on Modeling the Ocean

8th International Workshop on Modeling the Ocean (IWMO)
8th
IWMO-2016
International Workshop on
Modeling the Ocean
Aula G. Prodi, Alma Mater Studiorum
Università di Bologna
June 7-10 2016
BOOK OF ABSTRACTS
1
8th International Workshop on Modeling the Ocean (IWMO)
KEYNOTE PRESENTATIONS
June 7, 2016 h 09.30 - 10.00
1) KEYNOTE PRESENTATION: Simona Masina INGV-CMCC, Bologna (Italy)
Reconstructing the past ocean variability from reanalyses
Simona Masina (1,2)
(1) CMCC, Bologna, Italy, (2) INGV, Bologna, Italy
In the last two decades, climate research has benefitedfrom the continuous
development of analysis systems dedicated to operational monitoring and forecasting
which opened up the possibility of exploiting the state of the art modeling and data
assimilation tools to reconstruct and study the ocean during the past decades. This
was feasible also thanks to the increasing availability of long time series of qualified in
situ and remotely sensed observations.Retrospective analyses(or simply reanalyses or
ocean syntheses), indeed combine quality controlled reprocessed ocean observations
with a state-of-the-art ocean generalcirculation model (OGCM) using a data
assimilation method to estimate the time-varying three-dimensional state of the
ocean. Ocean reanalyses benefit from data assimilation algorithms that are usually
inherited fromoperational oceanography, although theyrequire specific treatment in
order to avoid spurious driftsstemming from instrumental or model biases.
Unlikeobservation-only products, ocean reanalyses take advantage of time-varying
atmospheric forcing, usuallycoming from an atmospheric reanalysis, and dynamical
andphysical balances implied by the OGCM. Here we give an excursus on the
availability of global and regional ocean reanalyses, their applications, their strengths
and weaknesses, and their future developments.
June 7, 2016 h 13.30 - 14.00
2) KEYNOTE PRESENTATION: A.Blumberg; Stevens Institute of Technology
Hoboken, USA
Forecasting and Visualization to Support America’s Cup Sail Boat Racing
Alan Blumberg1, Nickitas Georgas1, Thomas Herrington1, David Runnels1,
Giovanni Coppini2, Nadia Pinardi2, Rita Lecci2Giuseppe Turrisi2, Ivano Carluccio2, Fabio
Montagna2, and Sergio Cretì2
Stevens Institute of Technology1, Centro Euro-Mediterraneo sui Cambiamenti
Climatici2
The Louis Vuitton America’s Cup World Series of sailboat racing returned to New York
Harbor after nearly 100 years with its 45 ft foiling catamarans capable of 25 to 30kt
speeds. The presence of swift currents and turbulent winds were certain to make for
2
8th International Workshop on Modeling the Ocean (IWMO)
outstanding racing and cause a few difficulties. To provide the most reliable forecasts
of conditions in New York Harbor for May 6 – 8, 2016, collaboration betweena team of
American and Italian oceanographic researchers was established. The forecasting
continues the deterministic modeling Stevens has been doing since 2006 with their
operational
New
York
Harbor
Observing
and
Prediction
System
(www.stevens.edu/maritimeforecast/). NYHOPS provides sea-state (currents, water
level, temperature, salinity), weather conditions (wind, pressure, air temperature and
cloud cover) and waves (height, period and direction). The forecasts extend 72 hours,
are updated four times per day, and are published hourly. The Stevens Estuarine and
Coastal Ocean Model, a derivative of the Princeton Ocean Model forms the basis of the
dynamics. NYHOPS forecasts covering the urban and coastal waters of New York, New
Jersey and Connecticut use meteorological forcing from the National Weather
Service’s North American Mesoscale (NAM) atmospheric forecast model and USGS
river flow gauges.
The visualization and graphical rendering of the NYHOPS forecasts were a critical part
of the communication of the forecasts to the public. Detailed maps of the race area
using real-time information were created and provided each morning before the racing
began.Model outputs are automatically downloaded from aStevens ftp site and
processed by CMCC. Maps were created using NCL visualization software, transformed
in tiles and rendered on Google Maps. The processing chain of visualization was
installed on the CMCC supercomputer in Lecce (IT). Tiles, once created, were
automatically transferred and published through a web service hosted on an Amazon
service. Several levels of zooms were available on Google Maps through the website
and one zoomlevel on the corresponding smart phone app. The forecast maps are
available at: http://ny.sea-conditions.com/. The site was accessed throughout the
racing days by sailors and the technical support teams.The phone app was featured
on television segments and in several newspaper stories. A crowd estimated in excess
of 100,000 spectators lined the shoreline of the race area. Viewers in the United
States could watch the races live on NBCSN and NBC SPORTS .
June 7, 2016 h 15.30 - 16.00
3) KEYNOTE PRESENTATION: E. Stanev: Helmholtz Zentrum Geesthacht,
Germany
Ocean Forecasting: From Regional to Coastal Scales
Emil V. Stanev
Helmholtz Zentrum Geesthacht, Germany
In the past years, the Helmholtz Zentrum Geesthacht put in place the Coastal
Observing System for the North and Arctic Seas (COSYNA) in the frame of which
different aspects of forecasting the marine environment have been developed. This
paper describes these developments, which are based on recent advances in coastal
ocean forecasting in the field of numerical modelling, data assimilation and
observational array design. The region of interest is the North and Baltic Sea; most of
the coastal examples discussed in the paper are for the German Bight. Several preoperational applications are presented exemplifying the outcome of using the best
3
8th International Workshop on Modeling the Ocean (IWMO)
available science in coastal ocean predictions. They help to identify new challenges;
most of them are associated with resolving the non-linear behavior of coastal ocean,
which for the studied region, is manifested by the tidal distortion and generation of
shallow-water tides. Led by the motivation to maximize the benefit from observations,
the authors focus on the integration of observations and modelling by using advanced
statistical methods. The coastal and regional ocean forecasting systems do not run in
isolation, but are linked, either weakly by just using forcing data, or interactively by
using two-way nesting or unstructured-grid models. Therefore the problem of
downscaling and upscaling, which currently attracts much attention, is also addressed.
One example shown is the coupling of the coarse-resolution regional models by using
a two-way nesting method with fine resolution in the area of connecting straits. The
major part of the paper presents illustrations from assimilation of remote sensing, in
situ and HF radar data, prediction of wind waves and storm surges, as well as possible
applications to search and rescue operations, and modelling support for assessing the
environmental impact of wind parks. Concepts for seamless approaches to link coastal
and regional forecasting systems are also presented and the two examples given
illustrate (1) an application of unstructured-grid model for the Ems Estuary, and (2)
the potential influence of the information from coastal observatories or coastal
forecasting systems on the regional models.
June 8, 2016 h 10.00 - 10.30
4) KEYNOTE PRESENTATION: P. Lermusieaux; Massachussets Institute of
Technology (Boston, USA)
Internal-tide Interactions with the Background Ocean:
The case of the Gulf Stream and Middle Atlantic Bight Shelfbreak Front
P. Lermusieaux
Massachussets Institute of Technology (Boston, USA)
Internal tides in the Middle Atlantic Bight region are shown to be noticeably influenced
by the presence of the shelfbreak front and the Gulf Stream. To identify the dominant
interactions of these waves with subtidal flows, general vertical-mode momentum and
energy partial differential equations (PDEs) are derived for waves in slowly-varying,
spatially-variable background flow and density fields. The fully-nonlinear dynamics of
regional tide-background-ocean interactions are simulated with a primitive equation
model, which incorporates realistic summer-mesoscale features and atmospheric
forcing. The shelfbreak front, which has horizontally-variable stratification, decreases
topographic internal-tide generation by about 10\% and alters the wavelengths and
arrival times of locally-generated mode-1 internal tides on the shelf and in the abyss.
The (sub)-mesoscale variability at the front and on the shelf, as well as the summer
stratification itself, also alter internal-tide propagation. The Gulf Stream produces
anomalous regions of $\mathcal{O}$(20 mW m$^{-2}$) mode-1 internal-tide
energy-flux divergence, which are explained by tide-mean-flow terms in the mode-1
energy balance. Advection explains most tide-mean-flow interaction, suggesting that
geometric wave theory explains mode-1 reflection and refraction at the Gulf Stream.
Geometric theory predicts that offshore-propagating mode-1 internal tides that strike
the Gulf Stream at oblique angles are reflected back to the coastal ocean, preventing
4
8th International Workshop on Modeling the Ocean (IWMO)
their radiation into the central North Atlantic. These results provide an explanation for
the anomalous intermittent onshore energy fluxes previously observed at the New
Jersey Shelfbreak and linked with the generation of nonlinear internal waves.Applying
our general PDEs to diagnose the dominant internal-tide-background interactions in
other regions with fronts and/or background currents should be revealing. This is joint
work with Dr. Sam Kelly and the MSEAS group.
June 8, 2016 h 15.30 – 16.00
5) KEYNOTE PRESENTATION: B. Perez-Gomez; Puertos de Estado, Spain
Nowcast and forecast of sea level hazards
B. Perez-Gomez
Puertos de Estado, Spain
Climate change and its impact on sea level rise has increased awareness on sea level
hazards even for those coasts where they were not a big issue a few years ago. This
would be the case for example of Spain and the rest of the Mediterranean countries,
where the magnitude of tides and storm surges were very small in comparison to
other areas. At the same time, increased attention has been paid to other higher
frequency sea level oscillations such as "seiches" or tsunamis, that have led to the
upgrade of existing sea level networks to lower sampling and transmission latency
(around 1 min or less). These two facts have had an impact on the way sea level data
from tide gauges are analyzed in real-time and integrated in sea level forecasting
models. In this conference a description will be made of the recent developments on
sea level forecast and nowcast focusing on the example of the experience in Spain
and its potential application for the Mediterranean sea, with special attention to the
possibilities of multi-model techniques, by integration of the new operational models
in the region.
June 9, 2016 h 10.15 - 10.45
6) KEYNOTE PRESENTATION: G. L. Mellor; Princeton University, US
On Theories Dealing with the Interaction of Surface Waves and Ocean
Circulation
George Mellor
Princeton University, USA
The classic theory for the interaction of surface gravity waves and the general ocean
circulation entails the so-called wave radiation stress terms in the phase-averaged
momentum equation. The equations of motion are for the combined Eulerian current
and Stokes drift. On the other hand, a more recent approach includes the so-called
vortex force term in the momentum equation wherein the only wave property is
Stokes drift. The equations of motion are for the Eulerian current. The idea has gained
traction in the ocean science community, a fact that motivates this paper. A question
is: can both theories be correct? This paper answers the question in the negative and
5
8th International Workshop on Modeling the Ocean (IWMO)
presents arguments in favor of the wave radiation theory. The vortex force approach
stems from an interesting mathematical construct, but it does stand up to physical or
mathematical scrutiny as described in this paper. Although not the primary focus of
the paper, some discussion of Langmuir circulation is included since the vortex force
was first introduced as the basis of this oceanic cellular phenomenon. Finally the
paper explains the difference in the derivation of the radiation stress theory and the
vortex force theory: the later theory entails errors related to its use of curl and
reverse-curl (or uncurl) processes.
June 9, 2016 h 14.00 - 14.30
7) KEYNOTE PRESENTATION: M. Gregoire; Université de Liège (Liège,
Belgium)
Modelling hypoxia and its impact on the Good Environmental Status of
marine waters. The Black sea case.
Marilaure Grégoire, Arthur Capet2, Evgeny Ivanov, Luc Vandenbulcke
MAST (Modelling for Aquatic Systems) research group, University of Liège, Belgium
2 ECHO group, OGS Trieste, Italy
The problem of decreasing oxygen content (deoxygenation) of coastal and oceanic
waters worldwide has worsened in recent decades, primarily as a result of climate
change, agriculture and human waste. Deoxygenation of marine waters is predicted to
further worsen with continued increases in global temperatures and human population
size, with widespread consequences.The management and predictions of
deoxygenation call for a holistic approach of the ocean considering its numerous
interactions with other reservoirs (atmosphere, continents, and sediments) and the
impacts of multiple stressors. Mathematical models offer the required holistic and
integrative approach to manage Oxygen Minimum Zones and give essential
information on the understanding of the mechanisms at stake. Here, based on a
modelling exercise performed in the Black sea with a coupled tri-dimensional
hydrodynamic-biogeochemical model, we present an overview of processes that have
been found essential for simulating the oxygen dynamics and the impact of low
oxygen conditions on the biogeochemical cycling of essential elements (e.g. C, N). It
is known that the generation of hypoxic waters (O2< 60 µmol/kg) compromises the
Good Environmental Status (GES) of marine waters and affects the health of living
organisms but still the connection of ocean models with indicators of GES is not trivial
and calls for specific approach.Here, we propose to use a trait-based approach in
order to link the functional composition of the macrobenthos of the north-western
shelf that is seasonally submitted to hypoxia to the environmental conditions
predicted by the numerical models. This shows an example on how the wealth of
information on environmental conditions provided by ocean models can be connected
to indicators of GES. Finally, a regionalization of the seafloor is proposed based on the
significant trait-environment relationships.
6
8th International Workshop on Modeling the Ocean (IWMO)
June 10, 2016 h 09.00 - 09.30
8) KEYNOTE PRESENTATION: D. Obaton; Mercator-Ocean (Ramonville SaintAgne, France)
Ocean& marine services : the EuropeanCopernicus Marine Service
Dominique Obaton
Mercator Océan, France
Mercator Océan has been entrusted by the European Commission to implement,
operate and deliver the Copernicus Marine Environment Monitoring Service (CMEMS).
After 6 years of the MyOcean demonstration phase, the service has been now working
in an operational mode since May 2015.
The service proposed to users allowsdescribing and monitoring the ocean in real time
or for the past periods, at the surface and at any chosen depth for different
oceanographic variables. Applications cover a large span as marine resources, marine
and costal environment, maritime safety or climate, seasonal and weather
forecasting.
The producers are from different European countries; the catalogue offers 140
products: physical (including ice) and biogeochemical onesboth from numerical
models or observations (satellite and in situ) over the global ocean and the European
seas. The access to products is unique for the whole catalogue via the CMEMS web
portal and the service is open and free to anyone. The service desk ensures the
interface between the service and theusersi.e. provides support as well as answers to
any question and records the user feedback. Various information as product manual,
product quality, availability, delay and improvement of products, different agendas
and general information are posted and regularly updated on the website.
At the end of April, the Copernicus Marine service counts nearly 7000 subscribers and
more than 2000 users who have downloaded products the past 12 months which
correspond to 32 million of transactions and of a volume larger than 200Tb over the
year.
June 10, 2016 h 11.30 - 12.00
9) KEYNOTE PRESENTATION: G. Mannarini; Centro Euro Mediterraneo sui
Cambiamenti Climatici, Lecce, Italy
VISIR: anopen-source model and an operational system for Ship Route
optimization
Gianandrea Mannarini
Centro Euro-MediterraneosuiCambiamentiClimatici, Lecce/Italy,
VISIR (discoVerIng Safe and effIcient Routes) is a fully open ship routingmodel. This
is achieved through a GPL licensing of the source code1 and detailed model
documentationon open-access journals. This way, numerical optimization methods,
hydrodynamic effectsconsidered, approximations used, and their ranges of application
are documented and made availableto the scientific community.
1
www.visir-model.net
7
8th International Workshop on Modeling the Ocean (IWMO)
At the same time, VISIR model is employed in an operational system linked to the
operational provision of oceanographic and weather forecasts. The system also
includes customized PC and mobile interfaces for end-users2.
VISIR’s main architectural choices, the input oceanographic and weather forecasts,
and an outline of possible goals for a future community of VISIR developers andusers
are presented here.
References
[1]
Mannarini, G., Pinardi, N., Coppini, G., Oddo, P., and Iafrati, A.: VISIR-I: small vessels – leasttime nautical routes using wave forecasts, Geosci. Model Dev., 9, 1597-1625, doi:10.5194/gmd-9-15972016, 2016.
http://www.geosci-model-dev.net/9/1597/2016/gmd-9-1597-2016.pdf
[2]
Mannarini, G., Turrisi, G., D’Anca, A., Scalas, M., Pinardi, N., Coppini, G., Palermo, F., Carluccio,
I., Scuro, M., Cretì, S., Lecci, R., Nassisi, P., and Tedesco, L.: VISIR: Technological infrastructure of an
operational service for safe and efficient navigation in the Mediterranean Sea, Nat. Hazards Earth Syst.
Sci. Discuss., doi:10.5194/nhess-2016-32, in review, 2016.
http://www.nat-hazards-earth-syst-sci-discuss.net/nhess-2016-32/nhess-2016-32.pdf
[3]
Mannarini, G.; Lecci, R.; Coppini, G., “Introducing sailboats into ship routing system VISIR,” in
Information, Intelligence, Systems and Applications (IISA), 2015 6th International Conference on , vol.,
no., pp.1-6, 6-8 July 2015, doi: 10.1109/IISA.2015.7387962
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7387962&filter=AND%28p_Publi
cation_Number:7376844%29
2
www.visir-nav.com
8
8th International Workshop on Modeling the Ocean (IWMO)
ORAL PRESENTATIONS
Session: Climate dynamics and modelling
A reanalysis dataset of the South China Sea
Shiqiu Peng (1), Xuezhi Zeng (1)
(1)State Key Laboratory of Tropical Oceanography, South China Sea Institute of
Oceanology, Chinese Academy of Sciences, Guangzhou, China.
Ocean reanalysis provides a temporally continuous and spatially gridded fourdimensional estimate of the ocean state for a better understanding of the ocean
dynamics and its spatial/temporal variability. Here we present a 19-year (1992–2010)
high-resolution ocean reanalysis dataset of the upper ocean in the South China Sea
(SCS) produced from an ocean data assimilation system. A wide variety of
observations,including in-situ temperature/salinity profiles, ship-measured and
satellite-derived sea surface temperatures, and sea surface height anomalies from
satellite altimetry, are assimilated into the outputs of an ocean general circulation
model using a multi-scale incremental three-dimensional variational data assimilation
scheme, yielding a daily high-resolution reanalysis dataset of the SCS. Comparisons
between the reanalysis and independent observations support the reliability of the
dataset. The presented dataset provides the research community of the SCS an
important data source for studying the thermodynamic processes of the ocean
circulation and meso-scale features in the SCS, including their spatial and temporal
variability.
Session: Climate dynamics and modelling
Issues of the Indian Ocean warming in atmospheric and oceanic global reanalyses
Annalisa Cherchi (1), Abish B (2), Satyaban Bishoyi Ratna (3), Syam Sankar (2),
MR Ramesh Kumar (4), Andrea Storto (1), Antonio Navarra (1), Simona Masina (1)
(1) Fondazione Centro Euromediterraneo sui Cambiamenti Climatici, Bologna, Italy
(2) Nansen Environmental Research Centre India, Kochi, India (3) Application
Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
(4) National Institute of Oceanography, Goa, India
The Indo-Pacific Ocean (i.e. region between 30°E and 150°E) has been experiencing a
warming since the 1950s. During these decades, the large-scale summer monsoon
rainfall over India decreased and the frequency of Indian Ocean Dipole (IOD) events
increased. At the same time, the atmospheric moisture is found to decrease over the
East Africa/Arabian Sea and to increase over the western Pacific region. This is
accompanied by the strengthening (weakening) of the upward motion over the
9
8th International Workshop on Modeling the Ocean (IWMO)
western Pacific (East Africa/Arabian Sea) that, consequently, contributes to modulate
the western Pacific-Indian Ocean Walker circulation. During the same period, the lowlevel westerlies weakened over the peninsular India, thus contributing to the
reduction of moisture transport towards India and to decreased rainfall over the
Western Ghats and central-east India. In the more recent decades (i.e. 1979-2012),
the analysis of SST trends in the Indian Ocean (IO) evidences a positive IOD-like
pattern during the summer monsoon season. OLR and precipitation data show
increasing (decreasing) trend of convection/precipitation over the western (south
eastern equatorial) Indian Ocean, thus corroborating the picture of more intense and
more frequent IOD events. In the Indian Ocean the warming pattern had experienced
a distinct change since the mid 70s. In fact, after 1976 the IO has warmed
excessively during both warm and cold El Nino Southern Oscillation (ENSO) events
because of a displacement in the atmospheric circulation. The positive anomalies in
the upper ocean heat content and in the temperature profiles taken from CMCC global
ocean reanalysis during both types of events indicate that the persistent warming of
the more recent decades is distributed also at depth in the Indian Ocean. After 1976,
atmospheric and oceanic fields changed mostly during La Niña, with both ENSO
phases contributing to the warming of the Indian Ocean. Analysis of the 3D oceanic
fields helps understanding the dynamical processes in the Indian Ocean responsible
for the changes in the IOD events characteristics and on the relationship with ENSO.
Session: Climate dynamics and modelling
River runoff influences on the Central Mediterranean Overturning Circulation
G. Verri(1,2), N. Pinardi (1,2), P. Oddo(3), S. A. Ciliberti(1), G. Coppini(1)
(1)Centro Euro-Mediterraneo sui Cambiamenti Climatici, Italy (2) Department of
Physics and Astronomy, University of Bologna, Italy (3) Center for Maritime Research
and Experimentation CMRE, La Spezia, Italia
The role of riverine freshwater inflow on the Central Mediterranean Overturning
Circulation (CMOC) has been studied using a high-resolution ocean model based on
NEMO code (Madec, 2008) with a complete distribution of rivers in the Adriatic and
Ionian catchment areas. We started from the knowledge rivers affect the buoyancy
budget of the Adriatic Sea, since 1/3 of the Mediterranean discharge is here located
(Struglia et al., 2004; Ludwig et al., 2009), and make the Adriatic Sea a dilution basin
(Artegiani et al., 1997). We also expect rivers influence the Ionian Sea because the
Adriatic dense waters are one of the major drivers of the Ionian abyssal circulation
(Curchitser et al., 2001; Roussenov et al., 2001; Bensi et al., 2013). The impact of
river runoff on the Adriatic and Ionian Sea basins is assessed by a twin experiment,
with and without rivers, from 1999 to 2012. This study investigates the connection
between the Adriatic as a marginal Sea containing the downwelling branch of the antiestuarine CMOC and the large runoff occurring there. Overall the CMOC is
demonstrated to be driven by wind forcing at least as much as by buoyancy fluxes. It
is found that the CMOC is a persistent anti-estuarine structure extending over the
Northern Ionian Sea and the Southern Adriatic sub-region down to a 700-800m.
10
8th International Workshop on Modeling the Ocean (IWMO)
Secondary estuarine cells have been detected at the surface in the Northern Adriatic
sub-region and in the deep layers of the Middle Adriatic Pit and the Southern Adriatic
Pit, we show they strengthen in years of large river runoff. The Adriatic Sea is
dominated by the anti-estuarine downwelling branch of the CMOC also when large and
anomalous river runoff occurs and the resulting buoyancy budget becomes positive or
null. It is found that theoretically the Adriatic Sea cannot switch to an estuarine
circulation even if the largest runoff in the decade from 2000 to 2012 is considered
and the antiestuarine CMOC remains large and dominant over the estuarine cells.
However large river runoff can affect the CMOC strength, enhancing the amplitude of
the secondary estuarine cells and reducing the intensity of the dominant antiestuarine cell. High river runoff is demonstrated to reduce the volume of Adriatic
dense water formed in the Southern Adriatic Sea as a result of increased water
stratification and the spreading of the Adriatic dense water into the Ionian abyss is
affected as well.
References • Artegiani, A., Paschini, E., Russo, A., Bregant, D., Raicich, F., Pinardi, N., 1997a. The
Adriatic Sea General Circulation. Part I: Air-Sea Interactions and Water Mass Structure. J. Phys. Ocean.,
27: 1492-1514 • Artegiani, A., Paschini, E., Russo, A., Bregant, D., Raicich, F., Pinardi, N., 1997b. The
Adriatic Sea General Circulation. Part II: Baroclinic Circulation Structure. J. Phys. Ocean., 27: 1515-1532
• Bensi, M., Rubino, A., Cardin, V., Hainbucher, D., Mancero-Mosquera, I., 2013. Structure and variability
of the abyssal water masses in the Ionian Sea in the period 2003-2010. J. Geophys. Res. Oceans,
118(2), 931-943 • Curchitser, E., N., Haidvogel, D., B., Iskandarani, M., 2001. Transient Adjustment of
Circulation in a Midlatitude Abyssal Ocean Basin with Realistic Geometry and Bathymetry. J. Phys.
Oceanogr., 31, 725-745 • Ludwig, W., Dumont, E., Meybeck, M., Heussner, S., 2009. River discharges of
water and nutrients to the Mediterranean and Black Sea: major drivers for ecosystem changes dur- ing
past and future decades. Prog Oceanogr 80:199-217 • Madec, G., 2008. NEMO ocean engine. Note du
Pole de modlisation. Institut Pierre-Simon Laplace (IPSL), France, 27: 1288-1619 • Roussenov, V. M.,
Williams, R. G., Roether, W., 2001. Comparing the overflow of dense water in isopycnic and cartesian
models with tracer observations in the eastern Mediterranean. Deep Sea Research Part I: Oceanographic
Research Papers, 48(5), 1255–1277 • Struglia, M. V., Mariotti, A., Filograsso, A., 2004. River Discharge
into the Mediterranean Sea: Climatology and Aspects of the Observed Variability. J. Climate, 17: 47404751
Session: Climate dynamics and modelling
Impacts of Climate change on Ice ocean wave climate over the North-West
Atlantic Ocean
Jinyu Sheng (1), Lanli Guo (1)
(1)Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
A numerical study is conducted to investigate the impact of global warming induced
by possible climate change on ocean surface gravity waves over the northwest
Atlantic (NWA) Ocean. The climate scenario known as RCP8.5 is considered in this
study. This scenario corresponds to the pathway with the highest greenhouse gas
emissions. Changes in the ocean wave climate over the study region are quantified
based on 6 hourly ocean wave simulations for the 120-year period 1980-2100
produced by the third-generation ocean wave model known as WAVEWATCHIII. This
wave model is driven by surface winds produced by the Canadian Regional Climate
Model (CanRCM4). The study period is divided into the present (1980-2009) and
11
8th International Workshop on Modeling the Ocean (IWMO)
future (2070-2099) periods. In comparison with the present wave climate, the
significant wave heights will increase in the future climate over the northeast part of
the model domain and will decrease over other areas such as the mid-latitude region
between 30o-50oN, due mainly to the changes in winds in the future climate. It shows
that the 10 m winds (U10) and significant wave heights (Hs) increase over Davis
Strait and Labrador Sea during boreal winter are associated with the sea ice changes
in the future climate. The future changes of the 95th percentile of U10 and Hs are
twice as strong as changes in the seasonal means, and the maximum changes of the
95th percentile of U10 are mainly dominated by the changes in storm densities. An
analysis of inverse wave ages suggests that wind-driven ocean wave regimes occur
more frequently over the subtropical area and Labrador Sea. The dominant North
Atlantic storm-track region is found to shift northward, which is the precursor to
changes in the winds and ocean waves.
Session: Climate dynamics and modelling
Schwarz-Christoffel conformal mapping based grids for high resolution ocean
models
Shiming Xu
Tsinghua University
We propose new grid generation methods for global ocean general circulation models
based on Schwarz-Christoffel conformal mappings. By mapping areas with user
prescribed, irregular boundaries to those with regular boundaries (i.e., disks, slits,
etc.), we achieve the alignment of grid lines to the large scale coastlines, enhanced
spatial resolution in coastal regions, and easier computational load balance. Since the
generated grids are orthogonal curvilinear, they can be easily utilized by the majority
of ocean general circulation models which are based on finite difference and require
grid orthogonality. The proposed method addresses the arisen challenges in highresolution global ocean modeling, and can also be applied to the grid generation for
regional ocean modeling where complex land-sea distribution is present.
Session: Climate dynamics and modelling
Storm surges in the Western South Atlantic: generation and propagation
Ricardo de Camargo (1), Joseph Harari (2)
(1) Department of Atmospheric Sciences, University of Sao Paulo (2) Deaprtment of
Physical, Chemical and Geological Oceanography, University of Sao Paulo
The southern portion of the Atlantic coast of South America has peculiar conditions for
storm surge generation and propagation: a wide and long continental shelf combined
to one the most cyclogenetic areas around the world. Moreover, the astronomic tidal
amplitude varies significantly from the Argentinean coast to Uruguay and Southern
Brazil, and the interaction between tides and surges is still an interesting topic to build
knowledge. The coastal observations are not enough to a complete description of
these phenomena due to the small number of stations as well as the non-continuous
12
8th International Workshop on Modeling the Ocean (IWMO)
characteristics of the datasets. Based on that, this work tried to address these issues
using long series of numerical results given by an implementation of POM to the South
Atlantic with spatial resolution of 0.5 degree of latitude and longitude. The simulations
cover the period 1948-2010 and considered the 3D fields from SODA2.2.4 to the
specification of initial and boundary conditions as well as the NCEP Reanalysis I to the
atmospheric forcing of winds and fluxes. The model captures well the amphidrome
locations for the major astronomic tidal constituents when compared to TPXO7.1, and
the surge events are examined for 9 stations between Argentina and Brazil. One
interesting aspect of the results is the analysis of the propagation from south to north
in combination with the local wind forcing, which is decisive for the surge amplification
and occurrences in the northernmost stations.
Session: Climate dynamics and modelling
Development of EAKF assimilation system in FIO-ESM and reconstruction of
climate reanalysis data
Xunqiang Yin, Ying Bao, Zhenya Song, Fangli Qiao
First Institute of Oceanography, SOA, China
Since there is always exist some bias during the simulation of ocean and climate
system, data assimilation is urgently needed to properly absorb the observed
information into the numerical model in order to increase the precision of numerical
simulation or forecast. Among all the methods of data assimilation used in the study
of ocean and climate, ensemble adjustment Kalman filter (EAKF) is more suitable for
application due to its significant advantage. In this method, perturbing of observation
is avoided, the prior information from numerical model can be well preserved, and the
cost of computation and requirement of storage are also relatively smaller. An EAKF
assimilation system is developed for oceanic data assimilation for ocean models and
Earth System Model (ESM).
Based on the Earth System Model (ESM) of FIO-ESM, a method of perturbing the
initial ocean temperature by a tiny random value is used to set up the restarts for
ensemble runs. The satellite SST and SLA data have been assimilated into FIO-ESM
model. A climate system reanalysis data covering 1992-2013 have been reconstructed
from the assimilated results in element models of ocean, atmosphere, ice, land
surface, and ocean waves followed by an overall comparison of this dataset. The
comparison of the experiments before and after assimilation of FIO-ESM indicated that
the results are more reliable and capable to reproduce the evolution of climate
system. In order to assessing the reconstructed dataset, the reanalyzing data of ERAInterim, EN4 and GPCP, and the wave measurements by satellite altimeter provided
by AVISO are employed to compare with the climate reanalysis data reconstructed by
EAKF assimilation. The assessment shows that our reanalysis data can provide the
reliable climate character for the upper ocean, motions and vapor distribution in
atmosphere, ice evolution, and distribution of significant wave height. This dataset
can be further used in the study of climate events, climate prediction and it is
potentially helpful to improve our understanding on climate change.
13
8th International Workshop on Modeling the Ocean (IWMO)
Session: Coastal Interdisciplinary Modelling
Exchanges between the shelf and the deep Black Sea
Shapiro, G.I., Wobus, F., Zatsepin, A.G. , Akivis, T.M. and Zhou, F.
(1)Plymouth University, Drake Circus, Plymouth PL4 8AA, UK (2) P. P. Shirshov
Institute of Oceanology, Moscow, 36 Nakhimovsky pr, Moscow, Russia, (3) Second
Institute of Oceanography, 9 Xixihexia, Hangzhou, Zhejiang Province, China.
Exchanges between the shelf and the deep Black Sea : an integrated analysis of
physical mechanisms This study provides an integrated analysis of exchanges of
water, salt and heat between the north-western Black Sea shelf and the deep basin.
Three contributing physical mechanisms are quantified, namely: Ekman drift,
transport by mesoscale eddies at the edge of the NW Black Sea shelf and non-local
cascading assisted by the rim current and mesoscale eddies. The semi-enclosed
nature of the Black Sea together with its unique combination of an extensive shelf
area in the North West and the deep central part make it sensitive to natural
variations of fluxes, including the fluxes between the biologically productive shelf and
predominantly anoxic deep sea. Exchanges between the shelf and deep sea play an
important role in forming the balance of waters, nutrients and pollution within the
coastal areas, and hence the level of human-induced eutrophication of coastal waters
(MSFD Descriptor 5). In this study we analyse physical mechanisms and quantify
shelf-deep sea exchange processes in the Black Sea sector using the NEMO ocean
circulation model. The model is configured and optimized taking into account specific
features of the Black Sea, and validated against in-situ and satellite observations. The
study uses NEMO-BLS24 numerical model which is based on the NEMO codebase
v3.2.1 with amendments introduced by the UK Met Office. The model has a horizontal
resolution of 1/24×1/24° and a hybrid s-on-top-of-z vertical coordinate system with a
total of 33 layers. The horizontal viscosity/diffusivity operator is rotated to reduce the
contamination of vertical diffusion/viscosity by large values of their horizontal
counterparts. The bathymetry is processed from ETOPO5 and capped to 1550m.
Atmospheric forcing for the period 1989-2012 is given by the Drakkar Forcing Set
v5.2. For comparison the NCEP atmospheric forcing also used for 2005. The
climatological runoff from 8 major rivers is included. We run the model individually for
24 calendar years without data assimilation. For the analysis of propagation of cold
waters formed on the NW Black Sea shelf we use a passive tracer method. The tracer
is treated as an artificial dye that “stains” a water parcel within the defined area as
soon as it cooled below a 7°C temperature.To quantify the shelf–deep sea exchange,
the transport of water, salt and heat between the NW shelf and deep-sea regions is
calculated across an enclosed boundary (a “fence”) approximating the 200 m isobath
on the NW shelf plus two short segments connected to the coast. Partial transports
are also calculated for the surface layer (top 20 m) and the under-surface layer (from
20 m to the bottom). The 20 m level is approximately equal to the Ekman depth in
summer. It is also close to the depth of the biologically active euphotic layer. For
validation of the NEMO-BLS24 configuration we present comparisons of the model
with satellite-derived sea surface temperature measurements and with ship-derived
14
8th International Workshop on Modeling the Ocean (IWMO)
cross-sections that show the vertical structure. We also compare the model to
observations carried out during Black Sea cruises in 2004, 2007 and 2008. The model
represents well the sea surface temperature, the depth of the upper mixed layer and
the depth of the CIL, while overestimating the temperature in the core of the CIL by
approx. 0.5 °C. Mechanism 1: exchanges due to a frontal eddy. Numerical simulations
for the year 2005 (for which comprehensive remote sensed data is available) shows
that a significant cross-shelf transport was generated by a long-lived anticyclonic eddy
impinging on the shelf, sometimes assisted by a cyclonic meander of the Rim Current.
Over 69 days between April 23 and June 30, 2005, a volume of 2.84×1012 m3 of
water (102% of the entire volume of the shelf waters) was transported out of the
shelf and a similar amount onto the shelf (see details in Zhou et al. 2014). Mechanism
2: exchanges due to Ekman drift. During the short but intensive wind events of April
15 – 22 and July 1 – 4, 2005, 23% and 16% of shelf waters, were moved into the
deep-sea region, respectively. Due to the high intensity of cross-shelf exchanges, the
average renewal time for the NW shelf in the Black Sea was only 28 days in the
summer of 2005 (Zhou et al. 2014). Mechanism 3: exchanges due to assisted
cascading. Using the model run for 2003 as an example, we examine the fate of the
tracer after 5.5 months of model integration. At 100m depth we identify four anticyclonic eddies: two eddies west of the Crimea peninsula, one north of Sinop and one
west of Batumi. These eddies can be seen to assist cascading into the basin interior of
cold waters formed on a shallow NW shelf to a depth greater than at which they were
originally formed. The important result is that for many of the 24 studied years a
significant proportion of dense shelf water does not cascade locally off the NW shelf,
but is transported by the Rim Current over hundreds of kilometres before cascading
into the deep basin in the southern and southeastern Black Sea. This work has been
supported by EU PERSEUS and a number of Chinese and Russian national projects.
References Zhou, F., G. I. Shapiro, and F. Wobus, 2014: Cross-shelf exchange in the northwestern Black
Sea. Journal of Geophysical Research: Oceans, 119, 2143-2164.
Session: Coastal Interdisciplinary Modelling
Estuarine dynamics for ocean modeling: the case study of the Ofanto estuary
G. Verri(1,2), N. Pinardi (1,2), J. Tribbia(3), F. Bryan(3), Y. Tseng(3), G. Coppini(1)
(1) Centro Euro-Mediterraneo sui Cambiamenti Climatici, Italy (2) Department of
Physics and Astronomy, University of Bologna, Italy (3) National Center for
Atmospheric Research, Boulder, USA
The regional ocean models generally treat the riverine freshwater release in an
oversimplified way by means of climatological runoff, based on gauges located far
from river outlets, and zero or at most constant salinity values corresponding to the
runoff (MacCready and Geyer, 2010). Doing this the water exchange into the
estuaries, owing to the ocean water entrainment, is not represented. Our goals are a
comprehensive description of the physical processes involved in the water and energy
balance of the estuary and a realistic reconstruction of river freshwater discharge into
regional ocean models. Three approaches of estuarine dynamics are tested and
compared: the simple Knudsen’s relation (Knudsen, 1900), an upgraded version of
15
8th International Workshop on Modeling the Ocean (IWMO)
the Knudsen’s relation we developed with the addition of tides, and an estuary box
model developed by the University of Connecticut, UCONN, jointly with the National
Center for Atmospheric Research, NCAR (Garvine and Whitney, 2006; MacCready and
Geyer, 2010). In all the approaches, we assume the estuary is a two-layer rectangular
box with riverine freshwater entering through the upper layer at the estuary head,
while at the estuary mouth the ocean water enters through the lower layer and
estuarine water outflows through the upper layer. This is a rigorous representation for
well stratified estuary (Geyer and Smith, 1987) while may be lacking for highly mixed
estuaries. We consider the highly stratified estuary of the Ofanto River as our case
study and we chose the range January to March 2011 as time window, since this is a
period characterised by a high discharge and floods of the river as consequence of
local heavy rain events. The estuary box is coupled in 1-way mode with both the
hydrological model WRF-Hydro (Gochis et al., 2013) at the estuary head and the
regional ocean model based on NEMO code (Madec, 2008) at the estuary mouth. The
sensitivity tests on the estuary dynamics pointed out the tidal pumping strongly
affects the resulting salinity of the outflowing estuarine water by promoting an intense
mixing into the estuary. The explicit representation of the tidal and shear mixing into
the estuary is crucial as well. Moreover a set of sensitivity experiments has been
performed on the coastal dynamics off the Ofanto estuary by forcing the regional
ocean model with the runoff and salinity computed by the different approaches of the
estuarine dynamics. The results show that the added value of better representing the
estuarine dynamics and its effect on the coastal dynamics become particularly
powerful when the upwelling wind regime characterizes the shelf area off the estuary
(Chao, S. Y., 1987; Kourafalou et al., 1996). The UCONN-NCAR model is the only one
that is capable to represent a well-defined river plume during upwelling wind. On the
other hand, the estuary model based on the Knudsen’s relation with the addition of
tides is the most rigorous one from the theoretical point of view, thus new effort will
be devoted to the development of this new approach.
References • Chao, S. Y., 1987. Wind driven motion near inner shelf fronts Journal of Geophysical
Research: Oceans, 92(C4), 3849-3860 • Garvine, R. W., Whitney, M. M., 2006. An estuarine box model
of fresh- water delivery to the coastal ocean for use in climate models Journal of Marine Research, 64(2),
173-194 • Geyer, W. R., Smith, J. D., 1987. Shear instability in a highly stratified estuary. Journal of
Physical Oceanography, 17(10), 1668-1679. • Gochis, D. J., Yu, W., and Yates, D.N., 2013. The WRFHydro Model Technical Description and User’s Guide, Version 1.0 NCAR Technical Document, 120 pp •
Knudsen, M., 1900. Ein hydrographischer Lehrsatz Ann. Hydrogr. Mar- itimen Meteor., 28, 316-320 •
Kourafalou, V.H., Oey, L.Y., Wang, J.D., Lee, T.N., 1996a. The fate of river discharge on the continental
shelf. Part I: modeling the river plume and the inner-shelf coastal current Journal of Geophysical
Research 101 (C2), 3415-3434 • MacCready, P., Geyer, W. R., 2010. Advances in Estuarine Physics
Annu. Rev. Marine. Sci., 2(1), 35-58 • Madec, G., 2008. NEMO ocean engine. Note du Pole de
modlisation. Institut Pierre-Simon Laplace (IPSL), France, 27: 1288-1619
16
8th International Workshop on Modeling the Ocean (IWMO)
Session: Coastal Interdisciplinary Modelling
Simulating hydrodynamics and ice cover in Lake Erie using an unstructured
grid model
Ayumi Manome (1), Jia Wang (2)
(1) University of Michigan, (2) NOAA Great Lakes Environmental Research Laboratory
An unstructured grid Finite-Volume Coastal Ocean Model (FVCOM) is applied to Lake
Erie to simulate seasonal ice cover. The model is coupled with an unstructured-grid,
finite-volume version of the Los Alamos Sea Ice Model (UG-CICE). This model
(FVCOM-Ice hereafter) is applied to a shallow freshwater lake for the first time in this
study. We conducted multi-year simulations in Lake Erie from 2003 to 2012. The
results were compared with the observed ice extent, water surface temperature, ice
thickness, currents, and water temperature profiles. The older model results from the
Princeton Ocean Model coupled with an ice model (ICEPOM) are also included in
comparison. Seasonal and interannual variation of ice extent and water temperature
was captured reasonably. FVCOM-Ice outperformed ICEPOM in reproducing decay of
ice melting in spring, as well as the probability density distribution of ice thickness in
the spectrum of deformed ice.
Session: Coastal Interdisciplinary Modelling
Trigger conditions for bedload transport induced by wind wave and currents
in the Gulf of Gdańsk
Witold Cieślikiewicz, Aleksandra Dudkowska, Gabriela Gic-Grusza, Jan Jędrasik
Institute of Oceanography, University of Gdańsk, Gdańsk, Poland
The magnitude and the spatial distribution of wave and current induced bedload
transport in the coastal zone of Gulf of Gdańsk located in the southern Baltic, for
extreme weather conditions, are considered. The sediment of given grain-size starts
to move when the threshold values of the near bed velocity and the resulting shear
stresses are exceeded. The hydrodynamic conditions leading to such critical values are
investigated in this study. We refer to those conditions as the trigger conditions for
bedload transport. They include the meteorological situation, i.e. the wind speed and
the wind direction, and also the resulting deep and shallow water wave and currents
driven by wind. Hypothetical extreme meteorological conditions have been defined
based on 138-year NOAA data [1] then corresponding wave fields and sea currents for
those conditions have been generated in this study. On the other hand, the 21
extreme historical storms over the 44-year period 1958–2001 were selected, using
HIPOCAS project database [2], to simulate the hydrodynamic conditions in the Gulf of
Gdańsk. Within the HIPOCAS project, the REMO [3] reanalysis of meteo parameters
has been utilised. The extreme storm selection procedure was developed based on the
modelled significant wave height. The computation of deep and shallow water wave
fields for the extreme wind conditions were performed using numerical wave models
WAM [4] and SWAN [5] whereas the wind currents were modelled using the
17
8th International Workshop on Modeling the Ocean (IWMO)
hydrodynamic model M3D [6], developed in the IOUG based on the POM model [7].
Applying the estimated trigger conditions to the modelled hydrodynamic data, the
likelihood of the bedload transport appearing in the various locations of the Gulf of
Gdańsk is analysed. The directions and the magnitudes of the sediment transport
occurring in the Gulf of Gdańsk during the extreme meteorological and hydrodynamic
conditions defined and selected are also estimated.
[1] Compo, G.P., Whitaker, J.S., Sardeshmukh, P.D., Matsui, N., Allan, R.J., Yin, X., Gleason, Jr., B.E.,
Vose, R.S., Rutledge, G., Bessemoulin, P., Bronnimann, S., Brunet., M., Crouthamel, R.I., Grant, A.N.,
Groisman, P.Y., Jones, P.D., Kruk, M.C., Kruger, A.C., Marshall, G.J., Maugeri, M., Mok, H.Y., Nordli, Ø.,
Ross, T., Trigo, R., Wang, X., Woodruff, S.D., Worley, S. (2011). Review Article – The Twentieth Century
Reanalysis Project. Q.J.R. Meteorol. Soc., 137, 1–28. [2] Cieślikiewicz, W., Paplińska-Swerpel, B., 2008,
A 44-year hindcast of wind wave fields over the Baltic Sea, Coastal Engineering, Vol. 55, 894–905. [3]
Jacob, D., Podzun, R. (1997). Sensitivity studies with the regional climate model REMO. Meteorol. Atmos.
Phys., 63, 119–129. [4] WAMDI Group (1988). The WAM model – A Third Generation Ocean Wave
Prediction Model. J. Fluid Mech., 70, 113–126. [5] Booij N., Holthuijsen L. H., Ris R. C. (1996). The
SWAN wave model for shallow water. Proceedings of the 25th International Conference on Coastal
Engineering. Orlando, USA. [6] Jędrasik, J., Cieślikiewicz W., Kowalewski M., Bradtke K., Jankowski
A.,2008, 44 years hindcast of the sea level and circulation in the Baltic Sea, Coastal Engineering, 55,
849–860. [7] Blumberg A. F., Mellor G. L., 1987, A description of a three-dimensional coastal ocean
circulation model, pp. 1–16, [w] Three-dimensional Coastal Ocean Models, N. Heaps (Red.), Am.
Geophys. Union, 4, 208
18
8th International Workshop on Modeling the Ocean (IWMO)
Session: Coastal Interdisciplinary Modelling
Hydrodynamic connection between the Gulf of Saint Lawrence and adiacent
coastal 2 shelf waters of the North Western Atlantic Ocean
Yuan Wang (1), Jinyu Sheng (1)
(1)Department of Oceanography, Dalhousie University, Halifax, NS, Canada
Distributions of circulation and tracers in the Gulf of the St. Lawrence (GSL) are
affected by many physical processes such as tidal mixing, estuarine plume and
atmospheric forcing at the sea surface. The GSL is also affected by the large-scale
ocean circulation over the eastern Canadian Shelf and adjacent deep waters of the
northwest Atlantic (NWA) through Cabot Strait and the Strait of Belle Ile. The main
objective of this study is to have better understanding of dynamic connections of
circulation and hydrography in the GSL with those outside of the GSL through Cabot
Strait. The coupled circulation-ice model based on the NEMO is used this study. The
coupled model is applied to the northwest Atlantic Ocean (NWA) with a 1/12o
horizontal resolution and 50 vertical z-levels. The model is driven by a suite of
external forcing including tides, atmospheric forcing, tides and river runoff. The tidal
forcing consists of (a) tidal surface elevation and depth-mean currents of five major
constituents specified at the model open boundaries and (b) tide-generating potential
specified at each model grid. The atmospheric forcing at the sea surface is
taken/derived from the 6-hourly fields of Climate Forecast System Reanalysis (CFSR).
The model is also driven by the monthly climatology of freshwater runoff from fifteen
major rivers in the study region. The model is integrated for the 15-year period 19962010. A comparison between model results and oceanographic observations
demonstrates that the coupled circulation-ice model performs well in simulating tides,
density-driven circulation, ice cover, and temperature and salinity distributions in the
GSL and adjacent coastal and shelf waters. The analysis of model results confirms
previous findings that circulation and variability inside the GSL are affected
significantly by those outside the Gulf due to the major hydrodynamic connection
through Cabot Strait. It also shows that the inflow (northward) over the eastern part
of Cabot Strait is highly dynamic and has significant impact on the temperature and
salinity variability within the GSL.
Session: Coastal Interdisciplinary Modelling
A high-resolution modelling study of the circulation along the Campania
Coastal System
Paola de Ruggiero (1), Ernesto Napolitano (2), Roberto Iacono (2), Stefano
Pierini(1)
(1)Dipartimento di Scienze e Tecnologie, Università di Napoli Parthenope, Napoli, Italy
(2) ENEA - C.R. Casaccia, Roma, Italy
A high-resolution modelling study of the circulation along the Campania coastal
system (CCS) in the southern Tyrrhenian Sea is presented. The area includes three
19
8th International Workshop on Modeling the Ocean (IWMO)
adjacent, semi-enclosed shallow basins (the gulfs of Gaeta, Naples and Salerno)
facing the open deep sea, and represents an ideal site for investigating relevant
dynamical processes of general interest in coastal oceanography. A Campania
Regional sigma-coordinate Ocean Model (CROM) has been implemented in this region,
with a 1/144° resolution; nesting with an operational circulation model covering the
whole Tyrrhenian Sea with a 1/48° resolution is performed. Forcing is provided by
surface momentum, heat, and freshwater fluxes computed from the non-hydrostatic
SKIRON/Eta atmospheric modelling system outputs. A winter and a summer period of
the reference year 2009 are analyzed in detail. The relative importance of the flow
induced by remote large-scale currents through topographic interactions and of that
induced locally by the wind are found to vary, even over a weekly time scale, in all of
the three gulfs. An analysis of the high frequency variability shows that, besides the
current changes induced by the typical mid-latitude atmospheric synoptic variability,
inertial currents in the open sea and sea breeze-induced currents in the gulfs are
present. Model-data comparison is performed in the CCS with altimeter data, satellitederived turbidity distributions, and a high-frequency radar system. Significant modeldata agreement is generally found. This work was carried out in the framework of the
RITMARE Flagship project of the Italian M.I.U.R. (U.O. SP3-WP4-AZ1-UO03 managed
by CoNISMa).
Session: Coastal Interdisciplinary Modelling
Predictability of wind induced sea surface transport in coastal areas
A. Cucco (1), G. Quattrocchi (1), G. Umgiesser (2) and S. Zecchetto (3)
(1)CNR - National Research Council, IAMC - Institute for Marine Coastal Environment,
Loc. Sa Mardini, TorreGrande, 09170 Oristano, Italy. (2) CNR- National Research
Council , ISMAR- Institute for Marine Science, Arsenale - Tesa 104, Castello 2737/F,
30122 Venezia, Italy (3) CNR - National Research Council, ISAC - Institute for
Atmospheric Sciences and Climate. Corso Stati Uniti 4, 35127
In this work we investigated the predictability of the wind induced sea surface
transport in coastal areas. The wind fields predicted by two state-of-the-art
meteorological models, namely ECMWF and SKIRON, were used as forcing for a
hydrodynamic and particles tracking model applied to reproduce a set of observed
drifters trajectories in a costal area of the Mediterranean Sea. Parallel, a set of
anemometric data derived by in situ measurements were adopted as model forcing to
reproduce the set of observed drifter paths. Such an approach allowed to define a
baseline to be used as a reference when evaluating the effects of the predicted wind
accuracy on the numerical model solution. The accuracy of the simulation results
using the observed wind data as model forcing was fair and suitable for most of the
operational oceanographic purposes. It decreased between 1.2 and 1.5 times with
respect to the reference scenario, when using the wind data predicted by the two
meteorological models. In particular, the results obtained from the ECMWF scenario
were about 3 times more accurate than the ones obtained from the SKIRON one. The
uncertainties were strongly dependent on the range of the observed wind speeds
classes with a different behavior depending on the type of adopted wind data. Finally
20
8th International Workshop on Modeling the Ocean (IWMO)
the amplification of the errors in predicting the sea surface transport generated by the
errors in the predicted wind fields was investigated.
Session: Coastal Interdisciplinary Modelling
Mean currents induced by spatially damped
Application to Van Mijenfjorden in Svalbard
internal
Kelvin
waves:
Jan Erik H. Weber (1), Peygham Ghaffari (2)
(1) Department of Geosciences, University of Oslo, Oslo, Norway (2) Akvaplan-Niva,
Oslo, Norway
Csanady (1972) was apparently the first to suggest that the transport associated with
internal Kelvin waves may have a significant impact on the transport of near-shore
effluents in lakes. Motivated by this, Wunsch (1973) derived the solution for an
internal Kelvin wave forced by wind stress. He then calculated the Stokes drift of this
wave, assuming that the Eulerian drift contribution was negligible. His results
indicated that drift in internal Kelvin waves may explain certain observed circulation
patterns in lakes. As pointed out by Wunsch, a variable wind stress can excite internal
Kelvin waves. However, in layered systems with strong barotropic tidal flow over
bottom sills, we may find pronounced internal waves, e.g. Farmer and Smith (1980).
In Arctic regions, with ice cover for a long period of the year, the barotropic tide will
constitute the main generating mechanism for internal waves (Støylen and Weber
2010). Along the Siberian Shelf and in the Canadian Archipelago we find considerable
internal wave activity due to tidal forcing (Levine 1990; Morozov et al. 2008). The
Stokes drift associated with Kelvin waves in a continuously stratified fluid is well
described in the literature (Wunsch 1973; Weber et al. 2014; Weber and Ghaffari
2014). In particular, for a fluid with a pronounced pycnocline, the Stokes drift of the
first baroclinic mode has a strong negative value near the depth where the BruntVäisälä frequency has its maximum (Weber et al. 2014). The lost momentum in
spatially damped internal Kelvin waves reappears as Eulerian mean currents through
the action of the mean wave Reynolds stresses and the Coriolis force. The latter
produces vertical stretching of vortex lines which is related (through density
conservation) to the horizontal advective density flux in steady flow. A novel
expression is derived for the steady balance between the frictional force on the
Eulerian mean flow and the forcing from the wave field. The forcing can be expressed
in terms of orthogonal eigenfunctions for internal waves (Lighthill, 1969; Gill and
Clarke 1974). For arbitrary values of the Brunt-Väisälä frequency it is shown that the
wave forcing is always positive, and proportional to , where z is the vertical
coordinate. Therefore, unlike the Stokes drift velocity in internal Kelvin waves, the
wave-induced Eulerian mean current is always in the direction of the waves. The total
Lagrangian mean drift (Stokes + Euler) is trapped to the coast within the internal
Rossby radius. The results are illustrated by an example from Van Mijenfjorden in
Svalbard, which is an arctic sill fjord at at 77.5o N, 15.5o E where the internal wave is
generated by the action of the barotropic semi-diurnal tide. It is very likely that the
small, but persistent drift induced by these waves near the right-hand shore may
induce a cyclonic mean circulation in the fjord.
21
8th International Workshop on Modeling the Ocean (IWMO)
References Csanady, G. T., 1972: Response of large stratified lakes to wind. J. Phys. Oceanogr., 2, 3-13.
Farmer, D. M. and J. D. Smith, 1980: Tidal interaction of stratified flow with a sill in Knight Inlet. DeepSea Res. Part I, 27, 239–254. Gill, A. E., and A. J. Clarke, 1974: Wind-induced upwelling, coastal
currents and sea-level changes. Deep-Sea Res., 21, 325-345. Levine, M. D., 1990: Internal waves under
the Arctic pack ice during the Arctic Internal Wave Experiment: The coherence structure. J. Geophys.
Res., 95, 7347-7357. Lighthill, M. J., 1969: Dynamic response of the Indian Ocean to onset of the
Southwest Monsoon. Phil. Trans. R. Soc. London A, 265, 45-92. Morozov, E. G., V. T. Paka, and V. V.
Bakhanov, 2008: Strong internal tides in the Kara Gates Strait. Geophys. Res. Lett., 35. Støylen, E., and
J. E. H. Weber, 2010: Mass transport induced by internal Kelvin waves beneath shore-fast ice. J.
Geophys. Res., 115, C03022, doi: 10.1029/2009JC005298. Weber, J. E. H., K. H. Christensen, and G.
Broström, 2014: Stokes drift in internal equatorial Kelvin waves; continuous stratification versus twolayer models. J. Phys. Oceanogr., 44, 591-599. Weber, J. E. H. and P. Ghaffari, 2014: Mass transport in
internal coastal Kelvin waves. Eur. J. Mech. B/fluids, 47, 151-157. Wunsch, C., 1973: On the mean drift
in large lakes. Limnol. Oceanogr., 18, 793-795.
Session: Coastal Interdisciplinary Modelling
Modelling Ocean Tides with an All-Source Green Function and the JPL Solar
System Ephemeris
Zhigang Xu
Maurice Lamontagne Institute, Fisheries and Oceans Canada, Mont-Joli, Quebec,
Canada
This talk presents a new method to model ocean tides, using the All-Source Green’s
function (ASGF)andthe JPL Solar System Ephemeris (DE430 and DE431). The
ASGFdynamically connects a point of interest (POI)where tidal predictions are
neededwith the global ocean. It can be pre-calculated with a numerical model for
linearized and depth-averaged shallow water equations. Once prepared, it can be
repeatedly used as a convolution kernel to model tides at the POI for any period of
time. The convolution can be quickly computed through fast Fourier transform and its
invers.
The JPL Solar System Ephemeris gives position vectors of the Moon and the Sun
relative to the Earth’s center with sub-meter high accuracy for any time. The tidal
forcing at any point of the global ocean surface can thereby be directly calculated
rather than resorting to Doodson’s(1921) harmonic series summation.
Besides using the JPL ephemeris as a modern way to calculate the tide forcing,
another novelty with the ASGF method is its using singular value decomposition (SVD)
for assimilation of tidal observations. With the SVD technique, the ASGF convolution
can be further cast as a regression model with the singular values treated as
regression parameters.
In terms of convolution of a response kernel with external force, this new method is
similar to the response method proposed by Munk and Cartwright (1966) because
both m.However an important difference between the two methods lies in their
response kernels. The response kernel of Munk and Cartwright’s method is statistically
obtained from the tide record at one location and the tidal force calculated for the
same location. Thus their response kernel describes the response in sea level only to
the local force, whereas in reality the force elsewhere also matters. In contrast, the
ASGF response kernel is calculatedwith the global shallow water equation model.It is
22
8th International Workshop on Modeling the Ocean (IWMO)
built with the long wave physics in the realistic ocean. It gives the responses to the
global tidal forcing field, not only to the local force.
A real-world example is provided by applying the ASGF response method to model the
tides observed at Sept-Îles Quebec, Canada.
Session: Coastal Interdisciplinary Modelling
Large Eddy Simulation of Particle Settling in the Ocean Mixed Layer
Yign Noh (1), Donggun Oh (1)
(1)Yonsei University
The settling process of suspended particles in the ocean mixed layer is investigated by
analyzing the Lagrangian motion of a large number of particles in the ocean mixed
layer simulated by LES with an aim to understand plankton dynamics and sediment
transport. The study focuses on how the turbulent structure of the ocean mixed layer
affects particle settling within the ocean mixed layer and the particle flux across the
mixed layer depth (MLD). For this purpose three different types of turbulence, the
convective mixed layer and the wind-driven mixed layer with and without Langmuir
circulation (LC), are considered, and MLD continues to increase by entrainment. In the
presence of large-scale eddies, such as convective eddies and LC, particles are swept
downward rapidly and the particle concentration is almost uniform within the mixed
layer, contrary to the wind-driven mixed layer without LC, dominated by small-scale
eddies. On the other hand, large scale eddies suppresses the downward transport of
particles ultimately by trapping them within eddies. The particle flux across the MLD is
evaluated in terms of the terminal velocity of a particle in a still fluid, turbulent
velocity scale within the mixed layer generated by wind stress or convection, and the
entrainment velocity at the MLD. It is found that the escape of particles from the
mixed layer occurs stochastically, and its probability is determined by turbulence at
the mixed layer and the entrainment velocity.
Session: Coastal Interdisciplinary Modelling
Temporal scales for nearshore hits of current-driven pollution in the Gulf of
Finland
Bert Viikmäe (1), Tarmo Soomere (1, 2), Tomas Torsvik (1)
(1) Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21,
Tallinn, Estonia (2) Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn, Estonia
The Baltic Sea, which is designated as a Particularly Sensitive Sea Area (PSSA) by the
International Maritime Organisation, is the host to one of the most fragile boreal
brackish-water environments and many marine protected areas. Still up to 15% of the
world's international ship cargo is carried over this relatively small water body and the
intensity of ship traffic is gradually growing. Sustainable management of this traffic
flow is a major challenge. In this study we focus on the transport of various adverse
23
8th International Workshop on Modeling the Ocean (IWMO)
impacts and employ the framework in which the direct impact of wind and waves on
their drift is ignored. Random disturbances affect single trajectories and their
spreading but the pattern of frequently hit nearshore areas, the time of drift and the
frequency of hits are almost invariant. While the probability of the hits of open ocean
coasts by pollution can be reduced by shifting shipping routes farther offshore, the
problem for narrow bays, such as the Gulf of Finland, is how to minimise the
probability of hitting any coast. A convenient way to address this problem is to use
statistical analysis of a large number of Lagrangian trajectories of test parcels
representing the potential pollution passively carried by surface currents. Such
analysis also allows identification and visualisation of several properties of currents
that cannot be extracted directly from the current fields. In this study the 3D velocity
fields simulated for 1965–2004, calculated by the Rossby Centre Ocean circulation
model (RCO) in the Swedish Meteorological and Hydrological Institute, are used for
the reconstruction of trajectories of tracers. The current-driven transport is analysed
by applying a Lagrangian trajectory model, TRACMASS. It uses pre-computed 3D
Eulerian velocity fields to evaluate an approximate path of selected water parcels
(equivalently, of an adverse impact with neutral buoyancy). We focus on trajectories
of parcels selected on a line that roughly follows the major fairway in the Gulf of
Finland from the Baltic Proper to Saint Petersburg. As we are specifically interested in
surface transport patterns, the selected parcels are locked in the uppermost layer. In
order to mimic the natural spreading of shipping lines, parcels are selected in a wider
belt covered by three model grid cells across the fairway. In each simulation one
parcel is selected at the centre of each of the 309 grid cells. The simulations in this
study cover the time interval 1965–2004 and are performed using the time window
length of days and time lag between windows days, resulting in 889,920 single
trajectories. In addition, the trajectories of parcels are analysed by dividing the model
fairway into three separate parts: upper, middle and lower, each represented with
103 grid cells. The performed long-term (1965–2004) simulations of Lagrangian
transport of various adverse impacts (incl. pollution in the uppermost layer of strongly
stratified water bodies) induced by surface currents in the marine environment largely
support the outcome of earlier studies but also reveal a number of interesting
features, with several practical implications. The central conjecture is that the results
obtained for main statistical properties of current-induced transport to the nearshore
over relatively short time intervals (about five years) already adequately represent
the core features of such transport over many decades. Moreover, the qualitative
patterns of this transport (e.g., in terms of the time it takes for the pollution to reach
the nearshore area) are also fairly robust. This time naturally increases almost linearly
when the underlying Lagrangian trajectories of pollution parcels are tracked during a
longer time interval; however, the locations of frequently hit coastal areas and the
variability of the hits along the coast remain practically the same. In essence, this
feature is consistent with the general perception that the typical locations of the
coastal wreck are commonly the same. An important practical implication is that
already simulations with relatively short Lagrangian trajectories, commensurable with
the average time of the pollution drift to the coast for the particular sea area, give an
adequate picture about the primary features of current-induced transport, most
probable locations of the beaching of adverse impacts and related time scales. Earlier
studies have revealed that minor shifts of short sections of the fairway may
considerably reduce the probability of drift of possible pollution to single Marine
24
8th International Workshop on Modeling the Ocean (IWMO)
Protected Areas. Our simulations show that a reasonable large-scale benefit can be
reached by such shifts in terms of the time it takes for the pollution to reach the
coast. Even though the spatial gradients of this time are generally moderate, a small
shift of certain sections of the existing fairway by just a couple of nautical miles may
potentially increase this time by 10%, equivalently, may provide one additional day to
combat with oil pollution before it reaches any vulnerable sea or coastal areas. The
best candidates for such a re-routing of ship traffic in the Gulf of Finland are segments
of the fairway between 26–26º30'E and to the east of longitude 27º30'E. Even though
short-term features of the time for a nearshore hit (particle age) have significant
temporal and spatial variability, several core features of the statistics and spatial
patterns of the considered measures of current-driven pollution transport are
remarkably stable. It is natural that the particle age exhibits clear seasonal course
and largely varies along the fairway in the study area. However, the spatial patterns
of this time seem to be robust and can be adequately derived already from relatively
short (5 years) simulations that use trajectories of fairly moderate length (on the
order of the typical time it takes for the pollution to reach the nearshore). The
probabilities of reaching the nearshore by adverse impacts released along the major
fairway, calculated for eight different 5˗year periods, do not reveal any trend. The
mean values for 1965–2004 for the probability for a nearshore hit, calculated
separately for the northern and the southern coasts, differ insignificantly. The largest
changes in the spatial patterns of nearshore hits are revealed for the proportion of
hits to the opposite nearshore areas. The Finnish coast is clearly more likely to be hit
from the pollution stemming from the fairway region between 1965–1990 while the
Estonian coast became more vulnerable in this context from 1990 onwards. This
phenomenon is eventually associated with an abrupt turn of the geostrophic air-flow
over the southern Baltic Sea by ~40° since 1987.
Session: Coastal Interdisciplinary Modelling
Development of a Coupled Ocean-Hydrologic Model to Simulate Pollutant
Transport in Singapore Coastal Waters
Xu Ming ,Vivien P. Chua
National University of Singapore
Development of a Coupled Ocean-Hydrologic Model to Simulate Pollutant Transport in
Singapore Coastal Waters Intensive agricultural, economic and industrial activities in
Singapore and Malaysia have made our coastal areas under high risk of water
pollution. A coupled ocean-hydrologic model is employed to perform threedimensional simulations of flow and pollutant transport in Singapore coastal waters.
The hydrologic SWAT model is coupled with the coastal ocean SUNTANS model by
outputting streamflow and pollutant concentrations from the SWAT model and using
them as inputs for the SUNTANS model at common boundary points. The coupled
model is calibrated with observed sea surface elevations and velocities, and high
correlation coefficients that exceed 0.98 and 0.95 are found for sea surface elevations
and velocities, respectively. The pollutants are modeled as Gaussian passive tracers,
and are released at nine upstream locations in Singapore coastal waters. During the
Northeast monsoon, pollutants released from Source 1 (Johor River), Source 2 (Tiram
25
8th International Workshop on Modeling the Ocean (IWMO)
River), Source 3 (Layang River) and Source 4 (Layau River) enter the Singapore Strait
after 4 days of release and reach Sentosa Island within 9 days. During the Southwest
monsoon, the dispersion time is roughly quadrupled, with pollutants from Sources 1 –
4 entering the Singapore Strait only after 12 days of release due to weak currents.
The overall mean dispersion coefficient K of 47.99 m^2/s during the Northeast
monsoon is roughly four times that of 11.33 m^2/s during the Southwest monsoon,
due to stronger streamflows in December and differences in the large-scale monsoon
effects.
Session: Circulation and Dynamics
Eddy–Topography Interaction Produces Quasi-stationary Jet between the
Subtropical and the Subarctic Gyres in the North Pacific Ocean (the Isoguchi
Jet)
Toru Miyama (1), Humio Mitsudera (2), Hajime Nishigaki (3), Ryo Furue (1)
[email protected]
(1) JAMSTEC, (2) Hokkaido University, (3) Oita University
Dynamics of a Quasi-stationary jet between the subtropical and the subarctic gyres in
the North Pacific Ocean (the Isoguchi Jet) is discussed using an idealized two-layer
model. The experiments using the model suggested a sea mound, which was merely
500 m high, exerted a jet along its eastern flank. The characteristics of baroclinic
Rossby wave was affected significantly by a barotropic flow over the sea mound. A
surface baroclinic jet was formed where a characteristic curve originating in the
subtropical gyre and one originating in the subpolar gyre met because the pycnocline
depth varies discontinuously there. Eddy – topography interaction produced the
anticyclonic barotropic circulation over the sea mound. Sensitivity experiments where
the height of the sea mound was changed suggested there is an optimal height for the
eddy – topography interaction.
Session: Circulation and Dynamics
Revisiting the problem of the Gulf Stream separation: on the representation
of topography in ocean models
Tal Ezer
Center for Coastal Physical Oceanography, Old Dominion University 4111 Monarch
Way, Norfolk, Virginia, 23508, USA
The difficulty of getting a realistic Gulf Stream (GS) separation in ocean models has
been a problem for a long time, from the early models of the 1980s to even some
modern models of today. The source of the problem is not completely understood yet,
since GS simulations are often sensitive to many different factors, such as numerical
parameterization, model grid, treatment of topography and forcing fields. A curious
result of early models was that terrain-following (sigma-coordinate) models seemed to
26
8th International Workshop on Modeling the Ocean (IWMO)
achieve a somewhat better GS separation than z-level models of similar resolution.
Therefore, an idealized generalized coordinate numerical model was used to compare
between a sigma-coordinate grid and a z-level grid while maintaining the same
numerical code and model parameters. Short-term diagnostic-prognostic calculations
focus on the initial dynamic adjustment of the GS from a given initial condition and
imposed boundary conditions. In diagnostic calculations, the GS is adjusted to the
observed density field, and the results are not sensitive to the grid type, but when
switching to prognostic calculations, the GS in the z-level model tends to immediately
develop an unrealistic GS branch that continues along the continental slope, while the
sigma-coordinate model shows a more realistic GS separation. If the z-level model is
modified to have a vertical wall instead of the continental slope, the GS separation
was improved. The results indicate a problem in the representation of sloping
topography in z-level models, and this was evident by a noisy JBAR (Joint Effect of
Baroclinicity and bottom Relief). The results are consistent with early studies that
show the important role that the JEBAR plays in the GS dynamics.
Session: Circulation and Dynamics
Recent advances in the understanding of the Tyrrhenian Sea dynamics
E. Napolitano, R. Iacono
ENEA- SSPT-MET-CLIM
In the last few years, analyses of the outputs of a high-resolution operational model,
running since 2009, and of the growing observational datasets, have led to significant
improvements in the understanding of the Tyrrhenian Sea circulation, and of its
variability. Robust mesoscale structures have been characterized, whose interactions
with the large scale flow driven by the winds and by the exchanges at the three open
boundaries, determine the basin surface circulation in the different seasons. Due to a
strong barotropic component of the dynamics, a tight coupling between the surface
and intermediate circulation was found, shedding light on previously unclear features
of the latter. Finally, analysis of a long altimetric time series has revealed that,
besides the expected, strong seasonal component, a significant low-frequency mode
of variability is present. This mode has a period of 6-7 years, and is mostly localized
in the western part of the basin.
Session: Circulation and Dynamics
A three-layer alternating spinning circulation in the South China Sea
Jianping Gan, Zhiqiang Liu, and Chiwing Rex Hui
Department of Mathematics and Division of Environment, Hong Kong University of
Science and Technology, Hong Kong, China
Understanding of the three-dimensional circulation in the South China Sea (SCS) is
crucial for determining the transports of water masses, energy, and biogeochemical
substances in the regional and adjacent larger oceans. The circulation’s kinematic and
dynamic natures, however, are largely unclear. Results from a three-dimensional
27
8th International Workshop on Modeling the Ocean (IWMO)
numerical ocean circulation model and geostrophic currents, derived from
hydrographic data, reveal the existence of a unique three-layer cyclonic-anticycloniccyclonic (CAC) circulation in the upper (<750 m), middle (750-1500 m), and deep
(>1500 m) layers in the SCS with differing seasonality. An inflow-outflow-inflow
structure in Luzon Strait induces largely the CAC circulation, which leads to vortex
stretching in the SCS basin because of a lateral planetary vorticity flux in each of the
respective layers. The formation of Joint Effects of Baroclinicity and Relief (JEBAR) is
an intrinsic dynamic response to the CAC circulation. The JEBAR arises from the CAC
flow-topography interaction in the SCS.
Session: Circulation and Dynamics
Nonlinear Interactions Among Ocean Internal Waves In The Wake Of A
Moving Cyclone
Agostino Niyonkuru Meroni (1), Madeline Miller (2), Eli Tziperman (2), Claudia
Pasquero (1)
(1) University of Milan - Bicocca, (2) Harvard University
The nonlinear dynamics leading to the generation of superinertial internal waves in
the ocean, in the wake of a cyclonic storm, is investigated by means of theoretical
arguments and of numerical integration of the hydrostatic Boussinesq equations in a
simplified realistic open-ocean setting. The velocity fields are first decomposed into
internal baroclinic modes and then the energy transfer across modes and at different
frequencies is computed. The well known triangle condition for (k'_z, k''_z, k'''_z)
triad interactions in vertical wavenumber space, |k'_z ± k''_z| = k'''_z , in the case of
realistic (i.e. non constant) stratification can be transposed to a condition on the
interacting triads in baroclinic mode-number space. This confirms that the (n, m, l)
triad of modes interacts when |n ± m| = l and highlights that other mode-number
triads can be resonant and that even the interaction of a mode with itself becomes
possible. The energy transfer across modes is dominated by the advection of high
mode (m) waves by the second mode wave (n = 2), which is the most energetic, and
this results in the excitation of the l = m − 2 mode wave at the double inertial
frequency. The analyzed nonlinear interactions lead to a transfer of energy from the
near-inertial waves, directly excited by the storm, to the superinertial waves, which
typically propagate faster and further than their lower frequency parents and can lead
to internal mixing even at large distances from the region of the large air-sea
momentum fluxes.
28
8th International Workshop on Modeling the Ocean (IWMO)
Session: Circulation and Dynamics
Inertial Instability of Time Integration Schemes in Widely-Used Ocean
General Circulation Models
Jia Wang
NOAA Great Lakes Environmental Research Laboratory
Numerical finite-difference schemes of time integration in widely used ocean general
circulation models are systematically examined to ensure the correct and accurate
discretization of the Coriolis terms. There are several groups of time-integration
schemes that are widely used such as centered differencing (leapfrog) scheme, Euler
forward scheme, Runge-Kutta scheme, Adams-Bashforthd scheme. One group is
suitable for simulating an inertial wave system and geostrophicadjustment processes
in the ocean, while the other causes inertial instability in a numerical model. The
centered differencing scheme and its family are suitable for accurately reproducing
the inertial motion. However, Euler forward scheme and its (predictor-corrector)
family produce unstable inertial waves; this problem could be serious for a
calculationlonger than one week. The predictor–corrector scheme with special
treatment of the Coriolis terms is recommended as a replacement for the simple
Eulerforwardscheme. The explicit leapfrog schemes tend to overestimate the phase
frequency,whereas the Euler schemes and implicit schemes underestimate it. To
better simulate the correct phase frequency, an alternate use of an explicit scheme
(e.g., leapfrog) and an implicitscheme (e.g., Euler backward or Masuno scheme) is
strongly recommended to preserve the correct phase frequency.Some models such as
FVCOM and POM are used to validate the theoretical analyses above.
Session: Circulation and Dynamics
Volume transport through the Taiwan Strait and the effect of synoptic events
Wen-Zhou Zhang (1,2), Fei Chai (3), Hua-Sheng Hong (2) , Huijie Xue (3)
(1) Department of Physical Oceanography,College of Ocean and Earth Sciences,
Xiamen University,Xiamen, China (2) State Key Laboratory of Marine Environmental
Science, Xiamen University, Xiamen, China (3) School of Marine Sciences, University
of Maine, Orono, ME, USA
Volume transport through the Taiwan Strait during 2005-2008 was simulated using a
shallow water model forced by high spatio-temporal resolution meteorological data.
On average, simulated monthly mean transports ranged from a southward maximum
of 0.38 Sv in December to a northward maximum of 2.02 Sv in June, with an annual
mean northward transport of 0.78 Sv. These estimates are in agreement with the
published results based on bottom-mounted ADCP observations. Several sensitivity
experiments were conducted to separately examine possible influence of ignoring air
pressure or applying time-averaged wind forcing on the transport estimate. We found
that excluding the air pressure component in the model gave rise to an insignificant
difference (0.01 Sv) in the mean transport estimate. Using multi-year-averaged
29
8th International Workshop on Modeling the Ocean (IWMO)
monthly mean wind, however, provided markedly different results; it brought about a
magnitude change of up to 0.65 Sv for the monthly mean transport and 0.34 Sv for
the annual mean transport. The nonlinear parameterization of wind stress was mainly
responsible for the distortion.
Session: Circulation and Dynamics
Submesoscale variability in the upper northern South China Sea
Hongyang Lin (1), Zhiyu Liu (1), Quanan Zheng(2), Jianyu Hu(1), Zhenyu Sun(1)
and Jia Zhu (1)
(1) State Key Laboratory of Marine Environmental Science, and Department of
Physical Oceanography, College of Ocean & Earth Sciences, Xiamen University,
Xiamen, China (2) Department of Atmospheric and Oceanic Science, University of
Maryland, College Park, Maryland
Submesoscale processes are important for closing the oceanic energy pathway from
large to dissipative scales, as well as in transferring properties between the upper and
interior ocean. Based on high-resolution underway measurements of surface
temperature and salinity and near-surface velocity, this study seeks to disclose
submesoscale (1-20 km) characteristics of the upper northern South China Sea (SCS),
focusing on temperature-salinity (T-S) compensation and horizontal wavenumber
spectra in the surface mixed layer. In contrast to previous studies on horizontal
variability of the upper ocean, a non-compensating thermohaline variability is
observed in the northern SCS at submeso- and larger-scales. The characteristics of TS compensation show an evident dependence on topographic regime: a T-dominating
type of variability appears to occur on the shelf/shelf break, whereas a constructive
one is generally observed in the deep basin. On the shelf/shelf break of the northern
SCS, the horizontal wavenumber spectra of temperature and horizontal velocity
display a k^{-3} scaling at submesoscale. In the deep basin, a k^{-2} scaling is
observed in coherent mesoscale structures, whereas a k^{-3} scaling is observed in
quiescent ambient flows. Vigorous submesoscale processes occurring at the periphery
of coherent mesoscale structures are presumably responsible for flattening the
spectral slope toward a k^{-2} scaling.
Session: Circulation and Dynamics
Statistical analysis of near-inertial oscillations in Xisha area of the South
China Sea using mooring observations
Xiaofei Yi (1), Shuwen Zhang (1); Yiquan Qi (2); Lingling Xie (1); Feng Xu (1);
Quanan Zheng (3)
(1)Guangdong Ocean University; (2)South China Sea Institute of Oceanology;
(3)University of Maryland
Based on one year of mooring Acoustic Doppler Current Profilers (ADCP) data from
Augst 23, 2011 to Augst21, 2012, this study analyzes statistical features of 11 near-
30
8th International Workshop on Modeling the Ocean (IWMO)
inertial oscillation (NIO) events in the Xisha area of the South China Sea. The results
indicate that the NIO events characterized by near-inertial kinetic energy (NIKE) are
generated by Typhoons or winter storms. The NIKE in the subsurface layer of 50-450
m exhibits the remarkable seasonal variability with peak values in local autumn. The
NIO events have an e-folding timescale from 2 to 12 d. The phase velocity, vertical
wavelength, and frequency shift of these events are examined. The frequencies of
NIOs are mainly shifted to above the local inertial frequency , i.e., a blue shift, which
is related to the background vorticity. The maximum NIKE induced by typhoon Nalgae
was observed in October 5, 2011. The NIKE propagated downward from 50 to 300 m
during the event. Another strong NIO event observed in Febrary 24, 2012 had the efolding timescale of 6 days, which was induced by winter storm (the local air
temperature dropped for more than 10oC). Although the NIKE originates from
atmospheric forcing, the stratification affected by ocean eddies is also contributed to
its propagation and distribution.
Session: Circulation and Dynamics
A 60 years ocean reanalysis for the study of the Mediterranean Sea
circulation
Claudia Fratianni (1), Simona Simoncelli (1) Nadia Pinardi (2) Vladyslav Lyubartsev
(3), Roberto Ingrosso (3)
(1)INGV Bologna Italy (2) University of Bologna Department of Physics and
Astronomy Bologna Italy (3) CMCC Lecce Italy
A 60 years ocean reanalysis has been produced at INGV by combining, every day, the
output of the ocean model, forced by atmospheric surface fluxes and relaxed to SST,
and quality controlled ocean observations, through the data assimilation. This is one
of the two products produced by INGV for the reanalysis of the physical state of the
Mediterranean Sea available through the Copernicus Marine Environment Service
(CMEMS). The OGCM used is NEMO model implemented in the Mediterranean at
1/16°x1/16° horizontal resolution and 72 unevenly spaced vertical layers (Oddo et al.,
2009). The model is forced by momentum, water and heat fluxes interactively
computed by bulk formulae adapted to the Mediterranean case, using AMIP data
(Cherchi and Navarra, 2007). Heat flux is corrected proportionally to the difference
between the model and observed SST (Pinardi et al., 2003), with a relaxation
coefficient. Water balance is computed as Evaporation minus Precipitation and Runoff.
The evaporation is derived from the latent heat flux while the precipitation and the
runoff are provided by monthly mean dataset. The data assimilation system is the
three-dimensional variation scheme called OceanVar, set up by Dobricic and Pinardi
(2008), that allows to correct model fields for the dynamic variables, assimilating both
in-situ and satellite data. We present the assessment of the reanalysis products,
following a standard validation methodology, and the ability to reconstruct the past
ocean variability in the Mediterranean Sea.
31
8th International Workshop on Modeling the Ocean (IWMO)
Session: Circulation and Dynamics
Toward an integrated Mediterranean and Black Sea regional model
Gianmaria Sannino (1), Bargagli A(1) , Carillo A. (1), Iacono R. (1), Napolitano E.
(1), Ozsoy E. (2), Pisacane G. (1), Sozer A.(2), Struglia M.V(1).
(1) Climate modelling and impacts laboratory. ENEA CR Casaccia. Rome, Italy
(2) Institute of Marine Sciences, Middle East Technical University (IMS-METU),
Erdemli, Mersin, Turkey
The Mediterranean-Black Sea system is characterized by significant exchanges of
water through very narrow and complex passages.
Through the Strait of Gibraltar, an upper flow of fresh and warm Atlantic water
spreads into the Mediterranean basin, and a lower flow of colder and saltier
Mediterranean water sinks in the North Atlantic. This two-way exchange is highly
variable, the most intense fluctuation originating from tidal currents. The interaction
between tides and the complex succession of contractions and sills that characterize
the bathymetry of the Strait, hydraulically controlled, makes the Strait of Gibraltar an
active element of the Mediterranean thermohaline circulation. In the same way the
Turkish Straits System (TSS), composed of the Bosphorus and Dardanelles Straits and
the Marmara Sea, has been found to be crucial in determining the interactions
between the Mediterranean and the Black Seas.
Simulations of the Gibraltar Strait and TSS dynamics, including the effect of tides,
have been performed using the MITgcm. Results will be shown, demonstrating good
skill in representing such processes.
An ad hoc configuration of the MITgcm, has also been used to investigate the effects
of both the internal equilibrium and lateral tides incoming through the Strait of
Gibraltar on the thermohaline circulation of the whole Mediterranean basin. Such
version of the model is able to explicitly solve the dynamics of the strait by locally
increasing the horizontal grid resolution. The results suggest that application of
explicit tidal forcing in a Mediterranean model has non negligible effects on the
simulated circulation in addition to the expected intensification of local mixing
processes. The western basin exhibits an immediate response to the different
characteristics of the inflowing AW observable in the modified deep water convection
processes in the Gulf of Lion. LIW dispersal paths in the eastern basin are also
affected by tides.
The results so far exposed naturally lead the way to the realization of a new
integrated model of the Mediterranean and Black Sea ocean system, in which the high
resolution non-uniform curvilinear orthogonal grid is extended to encompass the
whole domain. The grid has an overall regular horizontal resolution, locally enhanced
in the Straits in order to satisfy the minimum requirements that have been
established in the high resolution dedicated simulations.
32
8th International Workshop on Modeling the Ocean (IWMO)
Session: Circulation and Dynamics
Dense water flows - Effects of rotation
Jarle Berntsen and Guttorm Alendal
(1) Department of mathematics, University of Bergen, Norway
A sigma-level numerical ocean model is applied to the Dynamics of Overflow Mixing
and Entrainment (DOME) idealized density current problem. The focus in the present
study is on sensitivity to the vertical resolution. In a rotating system, there is a
transverse flow normal to the main direction of the dense water flows. This flow is
referred to as secondary circulation, and the role of the secondary circulation on
mixing and entrainment is investigated. Sensitivity of the processes in the bottom
boundary layer and in the interface between the plume and the ambient to the vertical
grid size is targeted. The numerical experiments are first performed with a relatively
coarse resolution (10 km) that does not allow a proper representation of eddies, and
then repeated with finer horizontal grid sizes.
Session: Ocean Predictions
The Mediterranean Forecasting System in the Copernicus Marine Service: last
improvements and skill assessment
Emanuela Clementi (1), Jenny Pistoia (1), Damiano Delrosso (1), Claudia Fratianni
(1), Massimiliano Drudi (1), Alessandro Grandi (1), Pierluigi Di Pietro (1), Nadia
Pinardi (1,2,3)
(1)INGV: Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy. (2) University
of Bologna, Italy. (3) CMCC: Centro Euro-Mediterraneo sui Cambiamenti Climatici,
Italy.
The Mediterranean Forecasting System (MFS) is a numerical ocean prediction system
that produces analyses, reanalyses and short term forecasts for the entire
Mediterranean Sea and its Atlantic Ocean adjacent areas. MFS became operational in
the late 90’s and has been developed and continuously improved at the National
Institute of Geophysics and Volcanology (INGV) in the framework of a series of EU
and National funded programs. The system is now part of the Copernicus Marine
Environment Monitoring Service (CMEMS) providing regular and systematic
information about the physical state and dynamics of the Mediterranean Sea through
the Med-MFC (Mediterranean Monitoring and Forecasting Center). This work is
specifically focused on the evaluation of the analysis and forecast modeling system
that covers the analysis of the current situation and produces daily updates of the
forecasts of the situation 10 days in advance. The system has been implemented in
the Mediterranean Sea with 1/16o horizontal resolution and 72 vertical levels and is
composed by the hydrodynamic model NEMO (Nucleus for European Modelling of the
Ocean) 2-way online coupled with the third generation wave model WW3
(WaveWatchIII) and forced by ECMWF atmospheric fields at 1/8o horizontal
resolution. The model solutions are corrected by the data assimilation system (3D
variational scheme adapted to the oceanic assimilation problem) with a daily
33
8th International Workshop on Modeling the Ocean (IWMO)
assimilation cycle of satellite Sea Level Anomaly (SLA) and vertical profiles of
Temperature and Salinity, using a background error correlation matrix varying
seasonally and in different sub-regions of the Mediterranean Sea. The validation of the
modelling system and the estimate of the accuracy of model products are key issues
to ensure reliable information to the users and the downstream services. To this end,
product quality activities are regularly assessed by performing both pre-operational
qualification and near real time (NRT) validation procedures: Pre-operational
qualification activities focus on testing the improvement of the quality of a new
release of the model system and relays on past simulation and historical data, while
NRT validation activities aim at the routinely and on-line skill assessment of the model
forecast and relays on the NRT available observations. The focus of this work is to
present the latest modelling system upgrades and the related improvements achieved
by showing the model skill assessment including comparison with independent (insitu
coastal moorings) and quasi-independent (insitu vertical profiles and satellite)
datasets. In particular the validation procedure shows that the new system is able to
better reproduce the evaluated hydrodynamic fields, particularly the Sea Level, with
respect to the previous one.
Session: Ocean Predictions
Ocean modeling systems in the Korea Hydrographic and Oceanographic
Agency (KHOA)
Boonsoon Kang, Do-Seong Byun
(1) Korea Hydrographic and Oceanographic Agency
The Korea Hydrographic and Oceanographic Agency (KHOA) is a government
organization of the Republic of Korea (ROK), representative agency providing
comprehensive maritime information such as nautical charts, tidal water-level and
currents. ROK is surrounded by seas in the three sides so that hydrographic and
oceanographic information is highly demanded for safety of marine activities.
Recently, a ship accident is vastly increased at ports in Busan, Gwangyang, Ulsan,
Incheon, Daesan and New Busan of ROK due to high vessel entry and departure.
KOHA has been providing predictive information of currents in the ports to support
maritime traffic. For the forecasting service, KHOA has developed ocean numerical
models based on the Regional Ocean Modeling System (ROMS) with realistic water
depth. Information of prediction models with the port-scale is obtained through
nesting over 3-steps. The largest model domain (1/4 degree) covers the North Pacific,
whose results are given in basin models at the boundary. The basin models (1/36
degree) in the East-China and Yellow Seas(YES) and East Sea (ES) again produce
boundary conditions for coastal models (200-500m resolution) which simulate sea
states in the ports. The model prediction for 3-days is produced every day, and served
on webpage with additional data such as sea route, harbour limit and so on.
34
8th International Workshop on Modeling the Ocean (IWMO)
Session: Ocean Predictions
Towards a fully operational eddying Global Forecasting System (GOFS16)
Andrea Cipollone (1), Dorotea Iovino (1), Simona Masina (1,2) and Vladimir
Stepanov(1)
(1) CMCC, Bologna, Italy (2) INGV, Bologna, Italy
The Global Ocean Forecasting system (GOFS16) is the first product of the recentlyborn global ocean/sea ice configuration at 1/16 degree resolution, called GLOB16 [1].
GOFS16 represents the efforts of CMCC over the last few years, in pushing global
forecasting systems to compete with regional operational systems in term of
resolution and accuracy of meso-scale predictions although over the full ocean basin.
This has been achieved by marrying progresses in ocean modelling and variational
techniques, coupling the physical NEMO-LIM2 ocean-sea ice model and a 3DVAR
scheme of [2]. The parallel I/O performances of this system have been further
improved to cope with GLOB16 configuration. The latter employs a "beyond-singleprecision" tri-polar grid with more than 2-billion grid points, having a horizontal
spacing of 6.9 km at the equator and 98 vertical levels ranging from 1 m at the
surface to 160 at the ocean bottom. GOFS16 is currently running in pre-operational
mode forced by operational ECMWF analyses and forecasts, with starting initial
conditions, at 1st October 2015, taken from a former 12-year integration of GLOB16
configuration forced by ERA-Interim reanalysis datasets. The talk presents a first
assessment about the capability of GOFS16 to carry out feasible global and regional
predictions. The first winter forecast productions (December/February), with 10-daylong forecasts launched every 7 days, is analysed. Performances of GOFS16 are
reported through a systematic comparison with diverse kind of observations (in-situ
data, satellite maps, along track sea level anomalies,..). The full chain, has further
been validated against a twin free-run simulation where assimilative procedure has
not been applied. [1] Iovino D., Masina S., Storto A., Cipollone A., and Stepanov V.
N., A 1/16° eddying simulation of the global NEMOv3.4 sea ice-ocean system, ,
Geosci. Model Dev. Discuss., doi:10.5194/gmd-2015-268 (in review), 2016. [2]
Storto, A., S. Masina, and A. Navarra (2015), Evaluation of the CMCC eddy-permitting
global ocean physical reanalysis system (C-GLORS, 19822012) and its assimilation
components, Quarterly Journal of the Royal Meteorological Society, doi:
10.1002/qj.2673.
35
8th International Workshop on Modeling the Ocean (IWMO)
Session: Ocean Predictions
Investigating tidal harmonic prediction approaches used in coastal numerical
forecasting models and software
Do-Seong Byun (1), Woo-Jin Jeong (2), Eunil Lee (1)
(1) Ocean Research Division, Korea Hydrographic and Oceanographic Agency (2)
South Sea Hydrographic and Oceanographic Office, Korea Hydrographic and
Oceanographic Agency
Numerical tide models are commonly-used worldwide to understand the
characteristics of tidal regimes and to forecast tides and tidal currents. Further,
harmonic analysis results of simulated tidal-heights and tidal-currents in each grid
point are used to produce information on the tide and tidal current harmonic
constants. This information can be employed, in turn, in tide and tidal-current
predicting and hindcasting through tidal prediction algorisms. In this study we
examine and test the characteristics of formulae for calculating the five astronomical
variables for the tide (tidal current) prediction used in coastal numerical models and
harmonic constant dataset based- prediction software. This allows us to make
recommendations as to which prediction algorithm modifications should be used in
different situations depending on required levels of temporal accuracy. In addition,
this study provides a fundamental critique of tide and tidal-current prediction
algorithms used in coastal numerical forecasting models and software. The
understandings produced are a key to modifying and upgrading tide models or
software in order to increase the accuracy of perpetual interannual tidal predictions
and, in particular, of tidal predictions made for tide-dominated coastal environments.
Lastly, we introduce the Numerical Tidal Stream Map, an application software for
predict tides and tidal currents developed by the Korea Hydrographic and Oceanographic Agency.
Session: Ocean Predictions
Ocean Ensemble Forecasting: Two Applications using Ensemble Winds from a
Bayesian Hierarchical Model
N.Pinardi (1), L.Lusito (2), R.Milliff (3)
(1) Department of Physics and Astronomy, University of Bologna, (2)CMCC, Lecce
(3) R.Milliff, CIRES, University of Colorado, Boulder, Colorado
A Bayesian Hierachical Model (BHM) combines scatterometer winds (Quickscat and
ASCAT) with ECWMF analyses/forecasts to augment the kinetic energy of the posterior
wind field at scales smaller than 20-50 km. The model assumptions have been
published in Milliff et al. (2011) and here we show two implementations in two
different ocean ensemble forecast system applications. The first is the deterministic
forecasting system of Pinardi et al. (2011) that demonstrates sample uncertainties in
10 day forecasts. In particular, the ensemble of ocean responses to the BHM winds
36
8th International Workshop on Modeling the Ocean (IWMO)
intensifies and concentrates uncertainty estimates at ocean mesoscales. In a second
application the BHM is adapted to use ASCAT winds from the Copernicus service. The
BHM posterior winds are used to drive ensemble surface wave forecasts. It is shown
that the ensemble spread in the surface wave simulations create an envelope
containing the observed significant wave heights and periods.
Session: Waves, currents and turbulence
Long-term transport and dispersion
Fukushima nuclear accident
of
137
Cs
released
into
ocean
off
Chang ZHAO1, Fangli QIAO1*, Guansuo WANG1, Changshui XIA1 and KyungTae JUNG2
1. Key Laboratory of Marine Science and Numerical Modeling, the First Institute of
Oceanography, State Oceanic Administration, Qingdao 266061, China, E-mail:
[email protected]
2. Korea Institute of Ocean Science and Technology, Ansan-Si 426-744, Republic of
Korea, E-mail: [email protected]
In the following days after the Fukushima nuclear accident which happened in 11th
March 2011, significant amounts of radioactive materials (131I, 134Cs and 137Cs) had
been leaking into the terrestrial and marine environments. The radionuclides model
was used to study the distribution of the 137Cs in the Pacific and the Indian Ocean
released from the Fukushima accident. The simulation on the distribution of 137Cs
agrees well with the observed profiles in the 9th November 2011, which proved the
validaty of the model. In the first year of our model run, the 137Cs is carried eastward
by the Kuroshio and its extension, spreading southward and northword meanwhile.
Four or five years after the accident, the 137Cs reaches the US coast with the surface
waters of the Pacific Ocean; its concentration is no higher than 3 Bq/m3. Ten years
after the accident, all the North Pacific Ocean is labeled with the 137Cs from the
Fukushima. The concentration is less than 1 Bq/m3 at that time. Thirty years after the
accident, the concentration of 137Cs in both the Pacific and the Indian Ocean is below
0.1 Bq/m3. Since the spreading path of 137Cs from the Fukushima nuclear accident is
just the migration route of the Pacific tuna, a kind of fish inhabit the western and
eastern North Pacific, it may cause radioactive contamination to the fish. In the
offshore seas of China, the 137Cs from Fukushima nuclear accident is very low (<0.2
Bq/m3) .
Session: Waves, currents and turbulence
A Mechanism of Ice-Band Pattern Formation Caused by Resonant Interaction
between Sea Ice and Internal Waves
Ryu Saiki, Humio Mitsudera
Institute of Low Temperature Science, Hokkaido University
Ice bands are frequently observed over marginal ice zones in polar seas. A typical ice
band pattern has a regular spacing of about 10 km and extends over 100 km in
marginal ice zone. Further, the long axis of an ice band lies to the left (right) with
37
8th International Workshop on Modeling the Ocean (IWMO)
respect to the wind direction in the Northern (Southern) Hemisphere. In this study we
show that the resonance between ice-band pattern propagation and internal inertiagravity waves below the sea ice well explains the ice-band pattern formation. Internal
waves are generated by the difference between the stress on the open water and the
stress on ice-covered water. This in turn reinforces to form ice band pattern with a
regular band spacing. Specifically, we have found that (1) A band spacing on the
order of 10 km is selected for by the resonance condition in which the ice-band
pattern propagation speed coincides with the phase speed of internal inertia-gravity
waves. (2) The ice bands tend to develop favorably when the wind direction and the
band propagation direction are nearly parallel. The velocity acceleration caused by the
periodic differential stress associated with the ice bands, driven by the wind parallel to
the band propagation direction, is important. The wind direction may turn to the left
(right) slightly in the Northern (Southern) Hemisphere as a result of the Coriolis force
acting on ice. Satellite images confirmed that the band spacing of the ice-band
pattern in the polar seas is consistent with this theory.
Session: Waves, currents and turbulence
XIA Changshui (1), JUNG KyungTae (2), WANG Guansuo (1), YIN Xunqiang(1)
(1) The First Institute of Oceanography, State Oceanic Administration (SOA),
Qingdao, China (2) Korea Institute of Ocean Science and Technology, Ansan 426-744,
Republic of Korea
Meso-scale eddies are important features in the South China Sea (SCS). The eddies
with diameters of 50-200 km can greatly impact the transport of heat, momentum,
and tracers. A high-resolution wave-tide-circulation coupled model was developed to
simulate the meso-scale eddy in the SCS in this study. The aim of this study is to
examine the model ability to simulate the meso-scale eddy in the SCS without data
assimilations The simulated Sea Surface Height (SSH) anomalies agree with the
observed the AVISO SSH anomalies well. The simulated subsurface temperature
profiles agree CTD observation data from the ROSE (Responses of Marine Hazards to
climate change in the Western Pacific) project. The simulated upper-ocean currents
also agree with the main circulation based on observations. A warm eddy is identified
in winter in the northern SCS. The position and domain of the simulated eddy are
confirmed by the observed sea surface height data from the AVISO. The result shows
that the model has the ability to simulate the meso-scale eddy in the SCS without
data assimilation. The three-dimensional structure of the meso-scale eddy in the SCS
is analyzed using the model result. It is found that the eddy center is tilted vertically,
which agrees with the observation. It is also found that the velocity center of the eddy
does not coincide with the temperature center of the eddy. The result shows that the
model has the ability to simulate the meso-scale eddy in the SCS without data
assimilations. Further study on the forming mechanism and the three-dimensional
structure of the meso-scale eddies will be carried out using the model result and
cruise observation data in the near future. Key Words: Meso-scale eddy, South China
Sea, high-resolution wave-tide-circulation coupled model
38
8th International Workshop on Modeling the Ocean (IWMO)
Session: Waves, currents and turbulence
Effect of warm eddy on typhyhoon intensity and development
WANG Guansuo, Qiao Fangli, Zhao Biao and XIA Changshui
The First Institute of Oceanography, State Oceanic Administration (SOA), Qingdao,
China
Super Typhoon Haiyan devastated portions of Southeast Asia, particularly the
Philippines, on November 8th, 2013. In this paper, observational data is used to
analyze the intensification process of Super Typhoon Haiyan. Observational data
showed that its encounter with a double warm-core ocean eddy, Typhoon Haiyan
intensified with maximum sustained winds increasing to 59 ms-1, while the typhoon’s
central pressure dropped from 970 hPa to 920 hPa. Numerical simulation and
obsevational data show that the presence of the warm-core eddy combined with SST
increases due to climate change led to a rapid intensification of Super typoon Haiyan.
Comparing these two factors, the warm-core ocean eddy, which brings significantly
more heat into the upper ocean layer, plays the leading role in the intensification,
with climate warming providing a lesser contribution. Moreover, due to the increased
thickness of mixed layer associated with the warm-core ocean eddy, Super Typhoon
Haiyan, did not cause a significantly lower sea surface temperature to the east of
Philippines, as is typical of typhoons, with the largest decline being only about 1 ℃.
Key words: tropical cyclone intensity, rapid intensification, sea surface
temperature, warm-core eddy, upper-ocean heat content anomaly
Session: Waves, currents and turbulence
From POM-1996 to IWMO-2016: An overview of 20 years of ocean modeling
and users participation
Tal Ezer
Center for Coastal Physical Oceanography, Old Dominion University 4111 Monarch
Way, Norfolk, Virginia, 23508, USA
The IWMO-2016 meeting in Bologna, Italy, in June 2016 marks the 20th anniversary
since the first POM users meeting, held in Princeton, USA, in June, 1996. The early
users group meetings led to the IWMO, and some of the scientists who attended the
first meeting in 1996 are also attending the 2016’s meeting. The concept of
community ocean models and the participation of users in model development, model
evaluation and model applications, had spread from a handful of models in the early
1990s (e.g., POM and MOM) to hundreds of different models today. The IWMO
symbolizes the international and collaborative nature of today’s ocean modeling
community. The history of this ocean modeling community over the past 20 years will
be reviewed using statistics and pictures from past users meetings. The review
reveals how ocean modeling changed from mainly numerical developments and
39
8th International Workshop on Modeling the Ocean (IWMO)
coastal processes to the developments of realistic large-scale ocean forecast systems.
I would like to dedicate this talk to Professor Emeritus George Mellor, who not only
contributed so much to ocean modeling, but also had the vision many years ago to
make the POM code freely available, creating one of the first ocean modeling users
group that is still active today.
Session: Air-sea interactions and atmospheric modelling
Assessment of atmospheric re-analyses and AMIP experiments to force
global and regional ocean re-analyses
Annalisa Cherchi (1), Satyaban Bishoyi Ratna (2), Simona Masina (1), Andrea
Storto (1), Chunxue Yang (1), Claudia Fratianni (3), Simona Simoncelli (3), Nadia
Pinardi (4)
(1) Fondazione Centro Euromediterraneo sui Cambiamenti Climatici, Bologna, Italy
(2) Application Laboratory, Japan Agency for Marine-Earth Science and Technology,
Yokohama, Japan (3) Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy (4)
Universita' degli Studi di Bologna, Bologna, Italy
Ocean re-analyses are powerful products to reconstruct the historical 3D-state of the
ocean and related circulation. At present a challenge is to have oceanic re-analyses
covering the whole 20th century. This study describes the exercise of choosing among
available datasets to force global and regional (i.e. in the Mediterranean Sea) oceanic
re-analyses from 1901 to present. In particular, we compared available atmospheric
re-analyses with a set of experiments performed with an atmospheric general
circulation model where SST and sea-ice concentration are prescribed. These types of
experiments have the advantage of covering long time records, at least for the period
for which global SST is available, and they can be performed at relatively high
horizontal resolutions. However they are limited by the intrinsic model biases in
representing the mean atmospheric state and its variability. In this study we show
that, within some limits, the atmospheric model performance in representing the basic
variables needed for the bulk-formulae to force oceanic data assimilation systems can
be comparable to the differences among available atmospheric re-analyses. In fact, in
the case of the Mediterranean Sea the high horizontal resolution of the set of SSTprescribed experiments combined with their good performance in representing the
surface winds in the area made them the most appropriate atmospheric forcing. On
the other hand, in the case of the global ocean, the atmospheric re-analyses have
been proven to be still preferable due to the better representation of spatial and
temporal variability of surface winds and precipitation.
40
8th International Workshop on Modeling the Ocean (IWMO)
Session: Air-sea interactions and atmospheric modelling
Parameterizing SST cooling induced by tropical cyclones
Jun Wei, Xin Liu, Guo-qing Jiang
Peking University, China
Sea surface temperature (SST) cooling induced by a tropical cyclone (TC) could exert
an important impact on its own intensity. Although a coupled air-sea interaction
model could provide such SST cooling, its accurate application is often a challenge due
to various complexities involved. The main goal of this study is to develop a fast,
robust, and effective parameterization scheme for TC-induced SST cooling that can be
used in TC weather prediction models. The following three steps are taken to achieve
this goal: (i) results from an idealized ocean simulation, together with theoretical and
temperature budget analyses, are used to isolate each mechanism causing TC-induced
SST cooling as a basis for the parameterization; (ii) building upon the SST cooling
parameterization schemes in the literature, this new SST parameterization scheme
includes mixing, advection, and SST cooling recovery process under the influence of
sea surface height and temperature in the ocean subsurface; and (iii) this improved
scheme is validated through a numerical simulation of Typhoon Matsa (2005) with the
Weather Research and Forecast model. Results show significant improvements in the
simulated storm intensity and reasonable SST after applying this TC-induced SST
cooling parameterization scheme. Although further tests with more TC cases are
needed, this scheme appears to have a great potential for being incorporated into any
TC weather prediction model. This scheme also provides visualization to examine the
TC-induced sea-surface circulations and SST cooling.
Session: Air-sea interactions and atmospheric modelling
Numerical simulation of a subseasonal SST warming event in the Bay of
Bengal in pre-monsoon season, 2010
Huiling Qin (1), Huijie Xue (1, 2), Dongxiao Wang (1), Guixing Chen (3)
(1) State Key Laboratory of Tropical Oceanography (LTO), South China Sea Institute
of Oceanology (SCSIO), Chinese Academy of Science, Guangzhou, China (2) School of
Marine Sciences, University of Maine, Orono, Maine, USA. (3) Center for Monsoon and
Environment Research, School of Atmospheric Sciences, Sun Yat-Sen University,
China
The Bay of Bengal experienced a large-scale anomalous warming in the Sea Surface
Temperature (SST) during 2010. The surface warming became most pronounced at a
sub-seasonal timescale prior to the onset of summer monsoon, which led to severe
coral bleaching in affected areas. Along with such a sub-seasonal warm SST event,
abnormal upper ocean circulation and salinity were also observed by the RAMA in-situ
mooring array. Using MITGCM, we investigate the mechanisms that are responsible
for this sub-seasonal SST warming. Numerical simulations show that dynamical and
thermal dynamical effects are almost comparable in magnitude. A combined effect of
41
8th International Workshop on Modeling the Ocean (IWMO)
the weakened latent heat loss due to weaker surface winds and the warm advection
by anomalous equatorial easterly winds was the main reason for the warm SST. The
anomalous surface winds also induced an anti-cyclonic circulation, which appeared to
distribute less saline water over the bay. The latter formed a barrier layer with stable
stratification, which became favorable for retaining the heat gain in the upper ocean.
The results highlight that the thermal conditions of the upper ocean may enhance a
short-term response to the anomalous atmospheric circulation and produce
exceptionally high SST.
Session: Air-sea interactions and atmospheric modelling
On the evolution of the Black Sea’s temperature and salinity and effect of
atmospheric forcing
Svetla Miladinova, Adolf Stips, Elisa Garcia-Gorriz and Diego Macias Moy
Institute for Environment and Sustainability, CEC Joint Research Centre, Via Enrico
Fermi, TP270 21027 Ispra (VA), ITALY
As a consequence of scientific interest and practical importance, the evolution of the
Black Sea hydrographic conditions and associated physical processes is attracting
great attention. Nevertheless, knowledge on the inter-annual development of the
temperature and salinity within the entire water column as well as in different
locations is still limited or covers particular years and locations. Defined by
temperatures less than 8oC in the sub-surface Black Sea’s waters, the Cold
Intermediate Layer (CIL) contains the lowest temperatures and most of the Black
Sea’s pycnocline. Despite the existing knowledge of the CIL formation and its main
features, there are some critical questions that deserve further explanation. How the
cold layer has evolved over the recent decades and what is the influence of
meteorological conditions on it? This study attempts to answer these questions by the
use of numerical simulations. A modelling study has been initiated to evaluate the
evolution of the Black Sea’s temperature and salinity based on the 3D General
Estuarine Transport Model (GETM) and General Ocean Turbulence Model (GOTM)
using high resolution (2 min by 2 min) grid, forced with two different sources of
meteorological forcings. Model performance at seasonal and inter-annual scales has
been assessed by comparing model outputs with satellite observation, available
occasional in-situ measurements and independent calculations of temperature and
salinity fields. Upper and deep water circulation, thermohaline structure, and submesoscale and mesoscale variability of the currents are correctly simulated by the
model. Strong correlation between the variation of sea surface temperature (SST) and
salinity (SSS), and weather conditions is identified. The inter-annual to inter-decadal
variations of mean CIL temperature and volume are thoroughly examined at particular
locations and over the entire deep sea basin. It is discussed whether the calculated
changes in the CIL physical structure are compatible with the SST and SSS,
temperature of the deep north-western waters, salt flux through the Bosphorus strait
and the regional atmospheric properties.
42
8th International Workshop on Modeling the Ocean (IWMO)
Session: Air-sea interactions and atmospheric modelling
Meteorological influences and storm surges in the coast of Mozambique
Ricardo de Camargo (1), Alberto José Bié (2), Alberto Francisco Mavume (3)
(1 and 2) Department of Atmospheric Science, University of Sao Paulo, Sao Paulo,
SP, Brazil (3) Department of Physics, University Eduardo Mondlane, Maputo,
Mozambique
The coast of Mozambique is often affected by intense meteorological activity over the
Mozambique Channel, either the tropical cyclones on its northern-central region or the
extratropical systems on the southern and central portions. Due to the large extension
of areas below 20m above sea level, this is one of the most vulnerable countries in
Africa, with about 50% of the whole population potentially exposed to natural
hazards. Storm surges combined to high fresh water discharge can drive huge coastal
floods, affecting both urban and rural areas. Within this context, we implemented the
Princeton Ocean Model (POM) in the Southwestern Indian Ocean domain (SWIO; 232°S, 28-85°E) using a regular grid with 1/6° of spatial resolution and 36 sigma
levels. The atmospheric forcing is given by wind fields and fluxes from CFSR (NCEP
Climate Forecast System Reanalysis) and the initial and boundary conditions are taken
from SODA2.2.4 (Simple Ocean Data Assimilation version 2). The implementation
includes tidal oscillations since the astronomical ranges are mainly relevant at the
central part of Mozambique, where the shelf is shallow and wide. The simulation
covers the period 1979-2010 and the basin scale results are verified through
comparisons with independent datasets such as OISST (Optimally Interpolated Sea
Surface Temperature), OSTIA (Operational Sea Surface Temperature and Sea Ice
Analysis) and OSCAR (Ocean Surface Current Analysis), as well as with the BRAN
(Bluelink ReANalysis). Then, the results related to the coast of Mozambique are
analyzed in terms of the few available observations of sea level to verify the distinct
tidal regimes and storm surges characteristics. Based on these findings, it’s possible
to say that a robust modeling system for tidal circulation and meteorological influence
is now achieved.
Session: Air-sea interactions and atmospheric modelling
Multi-scale ocean and atmospheric research in the western North Pacific
using the ATOP modelling system and observations
Leo Oey
National Central University, Taiwan
The ATOP (Advanced Taiwan Ocean Prediction;
http://mpipom.ihs.ncu.edu.tw/index.php) modelling system is
version of the Princeton Ocean Model (mpiPOM). I will discuss
using observations and ATOP model to understand physical,
climate and tropical cyclone dynamics in the western North Pacific
seas.
43
based on the MPI
recent advances in
biophysical, air-sea
Ocean and marginal
8th International Workshop on Modeling the Ocean (IWMO)
Session: Marine ecosystem modelling
Modelling giant red shrimp larval dispersal: density and connectivity patterns
Antonio Olita (1), Francesco Palmas (2), Piero Addis (2), Roberto Sorgente (1) and
Andrea Sabatini (2)
(1) Institute for Coastal Marine Environment, National Research Council (IAMC-CNR),
Oristano section, Torregrande(OR), Sardinia, Italy. (2) Department of Life Science and
Environment, University of Cagliari, Via T. Fiorelli, 1, 09126 Cagliari, Sardinia, Italy.
Connectivity and three-dimensional (3D) dispersion of the larvae of giant red shrimp
potentially released from known spawning areas along the Sardinia slope in the
western Mediterranean Sea were assessed using Lagrangian simulations forced by a
3D submesoscale permitting ocean regional model. Biophysical simulations using the
hydrodynamic conditions of the year 2012 were run to track propagules released from
known spawning areas during the spawning period of May to September. Passive
transport (PT) and vertical migration (VM) scenarios were tested, each with two
possible pelagic larval durations (PLDs) of 21 or 42 d. Dispersion of propagules in the
PT and VM scenarios differed in terms of travelled distance,export out of the domain
(larger for VM), and depth distribution (shallower and bimodal for VM due to larger
variability of encountered currents). Connectivity patterns were investigated among
eight release areas and four predetermined eco-regions, and results showed strong
connectivity among the NW, W, and S regions, whereas the E region was more
segregated. Differences in connectivity patterns among scenarios were related mainly
to the tendency of greater retention of propagules in the release area for the PT
scenarios. This finding, together with existing hypotheses of ontogenetic vertical
migration likely occurring during first egg-larval phases, suggest that the VM
scenarios are the most probable of the two hypotheses tested in the present study.
Strong connectivity between the W and S sides of Sardinia and the relative isolation of
the E side could have significant implications for the protection of this important
resource.
Session: Marine ecosystem modelling
Stating the Role of Fish and Fisheries on Marine Biogeochemistry through
End-To-End Modeling
Deniz DİŞA, Ekin AKOĞLU, Barış SALİHOĞLU
Middle East Technical University Institute of Marine Science, Erdemli, Turkey
The ocean has a crucial role in global carbon cycle through storage, transport, and
transformation of carbon components. More specifically, marine ecosystems control
the biological carbon pump by capturing inorganic carbon from the atmosphere into
the ocean, converting it into organic carbon through photosynthesis and transporting
44
8th International Workshop on Modeling the Ocean (IWMO)
to the ocean’s interior by means of sinking biogenic particles or active transport by
migrators. Playing a significant role in the marine food webs and having the ability of
moving actively, fish is thought to have a noticeable impact on carbon export from the
surface to the bottom of the ocean. For this reason, considering its increasing trend
especially after 1950s, fishing is expected to impact carbon cycle directly by changing
the fish biomasses. Despite this, impacts of fish and fisheries on marine
biogeochemistry are yet to be assessed quantitatively. This study aims to analyze the
impact of fish on marine biogeochemical processes by setting up an end-to-end model
that simulates lower and higher tropic levels of marine ecosystems simultaneously.
For this purpose, a one dimensional biogeochemical model involving carbon export
and nutrient cycles was online and two-way coupled to a food web model simulating
higher trophic level dynamics as well as fisheries exploitation. The coupled end-to-end
model enabled more realistic representation of the ecosystem with a holistic approach
and enabled analysis of the impacts of fish and fishing on marine biogeochemical
dynamics. Coupled model simulations estimated an approximately 15% decrease in
the carbon export compared to the biogeochemical model simulations which had no
fish compartment. This decrease was due to the incorporation of some part of the
carbon in the system by higher trophic level organisms, such as fish, by means of
trophic relationships rather than being exported to depth due to plankton mortality.
This enabled the coupled model to estimate carbon export fluxes more consistent with
the empirical data. Moreover, results obtained by applying different fishing intensities
indicated that changes in fisheries exploitation levels directly influence the marine
nutrient cycles and hence, the carbon export. As a result, unlike the models that do
not represent the fish explicitly, we show how marine biogeochemical processes are
impacted by the activity of fish assemblages and exploitation of fisheries.
Session: Marine ecosystem modelling
Nearshore Flow Patterns and Population Connectivity along the Eastern
Maine Coast
LeAnn Conlon (1), Huijie Xue (1), Phil Yund (2)
(1) School of Marine Sciences, University of Maine, Orono, ME 04469-5706, USA (2)
Downeast Institute for Applied Marine research and Education, Beals, ME 04611, USA
Understanding population connectivity for marine species with planktonic larvae is one
of the most pressing interdisciplinary challenges on the interface between ecology and
oceanography. Coupled biophysical models are a useful tool in assessing connectivity
because they incorporate physical variables such as temperature and flow patterns as
well as biological behaviors and ecological traits such as growth and mortality and
thus permit a comprehensive evaluation of the intricate processes that underlay
connectivity. We use a high-resolution coastal circulation model to simulate the
nearshore flow patterns along the eastern Maine coast to investigate population
connectivity of blue mussels (Mytilus edulis). This model is nested within the
NERACOOS Gulf of Maine Forecast System, and the simulation is validated with in situ
observations collected inside the model domain. Variability of the Maine coastal
current and across shelf transport is analyzed. To simulate dispersal, mussel larvae
are represented as Lagrangian particles, passive in initial simulations. These
45
8th International Workshop on Modeling the Ocean (IWMO)
simulations show particles lingering in the nearshore waters for several days, moving
among neighboring bays, and following the coastal current to result in a net
movement from northeast to southwest. Nevertheless, self-seeding as well as
localized transports to the northeast also occur. More runs with biological traits added
to the particles will be conducted to more closely simulate larval mussel dispersal and
population connectivity.
Session: Marine ecosystem modelling
Modeling spring-summer phytoplankton bloom in Lake Michigan with and
without riverine nutrient loading
Lin Luo (1), Jia Wang (2), Timothy Hunter(3), Dongxiao Wang (4), Henry
Vanderploeg (5)
(1) State Key Laboratory of Tropical Oceanography, South China Sea Institute of
Oceanology, Chinese Academy of Sciences, Guangzhou, China. (2) NOAA Great Lakes
Environmental Research Laboratory, Ann Arbor, Michigan, USA.
A coupled physical-biological model is used to simulate the ecosystem characteristics
in Lake Michigan. The physical model is the unstructured grid, Finite-Volume Coastal
Ocean Model (FVCOM). The biological model is a NPZD model, including phosphorus
as the nutrient, which is the limiting element in Lake Michigan, phytoplankton,
zooplankton and detritus. The models are driven by observed hourly meteorological
forcing in 1998 and the model results are calibrated by satellite and in situ data.
There were two phytoplankton blooms captured by remote sensing in Lake Michigan in
1998, one from March to May, and one during June. In this paper, those
phytoplankton blooms have been simulated by a coupled physical-biological model,
driven by observed meteorological forcing in 1998. The model reasonably reproduced
the lake currents. The biological model results, with and without riverine nutrient
loading, were compared with the remote sensing data. A 3-month-long donut-like
phytoplankton bloom that appeared in southern Lake Michigan was well simulated
only when riverine input was included, indicating the importance of riverine nutrient
input for supporting the growth of phytoplankton in Lake Michigan. The model with
riverine input also simulated well the results for a second event-driven phytoplankton
bloom during June that occurred in mid-south Lake Michigan, which lasted for about
20 days. High chlorophyll concentration that persisted in Green Bay for almost a year
was well simulated.
46
8th International Workshop on Modeling the Ocean (IWMO)
Session: Marine ecosystem modelling
A modelling study of the benthic-pelagic coupling in the northern Adriatic
Sea.
Giulia Mussap, Marco Zavatarelli
Alma Mater Studiorum Universita di Bologna, Dipartimento di Fisica e Astronomia,
Bologna, Italy
A fully coupled 1D physical-biogeochemical (BFM-POM) model was implemented in the
Gulf of Trieste (northern Adriatic sea). The model was used to evaluate the role of the
benthic-pelagic coupling processes in constraining the seasonal cycle of the main
biogeochemical processes. The benthic ecosystem structure compised five benthic
organisms functional groups and two benthic bacteria groups. Sensitivity experiments
to changing organic matter sedimentation fluxes and to diffusive benthic nutrient
fluxes were performed in order to assess the feedback of such coupling processes on
both the pelagic (primary and secondary) and benthic (benthic organism functional
type composition) dynamics. Preliminary results show a greater sensitivity of the
overall ecosystem biogeochemical dynamics to the benthic organic matter
sedimentation. Results could help in further understanding benthic-pelagic dynamics
in a shallow coastal environment and evaluating the importance of their inclusion in a
management oriented model.
Session: Marine ecosystem modelling
Assessing
ecosystem
health
in
the
Mediterranean
under alternative climatic and management scenarios
Sea
regions
C. Solidoro , Libralato S and the 'PERSEUS' group
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS
The ecosystem dynamics for key areas of the Mediterranean is described by using an
ecological model obtained by coupling state of the art physical and biogeochemical
models of the Mediterranean sea to a high trophic level food web model specific for
the area. We used integrated these models to compute and compare several
indicators measuring ecosystem health components (vigor, resilience and
organization) computed under reference and future climatic and fisheries scenarios
(2010-2020) Results show context dependent dynamics emerging from complex
integrated models, and give indication of direction of change of GES indicators that
suggest appropriate management actions to maintain ecosystem health.
47
8th International Workshop on Modeling the Ocean (IWMO)
Session: Ocean and marine services
The new Relocatable Ocean Model (SURF)
Francesco Trotta (1) , Elisa Fenu (2),Nadia Pinardi (1, 2)
(1) UNIBO (2) CMCC)
We present a numerical platform named Structured and Unstructured grid Relocatable
ocean platform for Forecasting (SURF). The platform is developed for short-time
forecasts and is designed to be embedded in any region of the large-scale
Mediterranean Forecasting System (MFS) via downscaling. SURF includes three basic
components: a structured grid hydrodynamic model based on the NEMO code, an
unstructured grid hydrodynamic model based on the SHYFEM code and a wave model
based on the SWAN code. Finally we present a case study where SURF is applied to
the Tuscan Archipelago in the western Mediterranean. Both models are validated
against CTD data collected during the Serious Game campaing around the Elba island.
Session: Ocean and marine services
Quantitative oil spill hazard mapping: statistical distribution, identi cation of
hot spots and predicting events
Antonio Augusto Sepp Neves, Nadia Pinardi
University of Bologna, Department of Physics and Astronomy
Since the seminal work carried out by Price et al., 2003, the field of quantitative oil
spill risk assessments (OSRAs) has evolved towards employing ensemble oil spill
simulations to address uncertainties inherent to the problem. The list of addressed
uncertainties, initially limited to the synoptic meteo-oceanographic conditions during
the spill event, has increased now encompassing variations in the maritime traffic
density, current fields uncertainties, and oil spill model setup. Increasing complexity
of the oil spill ensemble experiments resulted in an increased number of performed
simulations and analyzing the outputs in a fruitful and responsible way became itself a
challenge. Some authors have limited their analysis to the probability of a spill to
reach a coastal segment. Others experiments focused on the beached oil
concentrations solely. However, the literature demonstrates that both the frequency
and the magnitude of oil pollution events modulate the coastal impacts. Sepp Neves
et al., 2016 tried to take both components of the oil spill hazard into consideration but
identified major problems in their calculations/assumptions. The present work tackles
the problems identified by Sepp Neves et al., 2016. We analyzed the statistical
behavior of beaching events using an ensemble data set consisting on over 50,000 oil
spill simulations for the Algarve (Southern Portugal). Based on our results, we
proposed an oil spill hazard index compliant with the statistical characteristics of the
variable, taking into consideration both frequency and magnitude of beaching events
and allowing to estimate uncertainties in the quantification. The new index was
employed to identify and rank the major sources of oil spill hazard in the Algarve for
both operational and accidental events.
48
8th International Workshop on Modeling the Ocean (IWMO)
Session: Ocean and marine services
Mediterranean
applications
ocean
forecasting
products
in
support
marine
safety
Giovanni Coppini (1), MassimilianoDrudi (2), GerasimosKorres (3), Claudia Fratianni
(2), Stefano Salon (4), Gianpiero Cossarini (4), EmanuelaClementi (2), Anna
Zacharioudaki (3), Alessandro Grandi (2), Damiano Delrosso (2), Jenny Pistoia (2),
Cosimo Solidoro (4), Nadia Pinardi (2,5), Rita Lecci (1), Paola Agostini (1), Sergio
Cretì (1), Giuseppe Turrisi (1), Francesco Palermo (1), Anna Konstantinidou (3),
Andrea Storto (1), Simona Simoncelli (2), Pier Luigi Di Pietro (2), Simona Masina (1),
Stefania Angela Ciliberti (1), Michalis Ravdas (3), Marco Mancini (1), Giovanni Aloisio
(1), Sandro Fiore (1), Mauro Buonocore (1), Eric Jansen (1), Svitlana Liubartseva (1),
Enrique Alvarez Fanjul (6)
(1) Centro Euro-Mediterraneo sui CambiamentiClimatici (CMCC), Ocean Predictions
and Applications, Lecce, Italy ([email protected]), (2) IstitutoNazionale di
Geofisica e Vulcanologia (INGV), Bologna, Italy, (3) Hellenic Center for Marine
Research
(HCMR),
Greece,
(4)
IstitutoNazionale
di
Oceanografia
e
di
GeofisicaSperimentale (OGS), Trieste, Italy, (5) University of Bologna, Bologna, Italy,
(6) Puertos del Estado
The Mediterranean Oceanography Network for Global Ocean Observing System
(“MONGOOS”) is the GOOS Regional Alliance for the Mediterranean Sea.
MONGOOS partners collaborate to further develop operational oceanography in the
Mediterranean Sea promoting a continuous advance of the scientific understanding
and technological development upon which the MONGOOS services are based.
MONGOOS is challenged to increased downstreaming to enhance the usability of the
MONGOOS services and their usefulness for policy implementation, societal needs and
science. One of the main initiatives grown in the framework of MONGOOS is the ocean
forecasting system for the Mediterranean Sea. The latter consists today of the EU
Copernicus Marine Environment Monitoring Service (CMEMS) coordinated by Mercator
Ocean, which is working on an operational mode since 1st May 2015. The Service
provide a unique European Marine capability and core-knowledge base and a
catalogue of services meeting users’ requirements. The CMEMS MED-MFC delivers a
core information service to any user related to several areas of benefits be they
service providers or end-users from the commercial sector or from the R&D sector:
Maritime Safety, Coastal and Marine Environment, Marine Resources, and Weather,
Seasonal Forecasting and Climate activities.
CMEMS products are used in operational downstream sea situational services
developed by Centro Euro-Mediterraneo sui Cambiamenti Climatici (CMCC, Italy).
These services include, among the others:
- Ocean-Sar Search and Rescue service http://www.ocean-sar.com/ a on-line service
based on a lagrangian modelling capability (Leeway model) using CMEMS and ECMWF
forecast to provide particle trajectories simulation used by users such as Coast Guards
in order to optimize the search area in case of persons of objects lost at sea.
49
8th International Workshop on Modeling the Ocean (IWMO)
- Witoil Oil spill forecasting system http://www.witoil.com/ an operational web and
mobile service for predicting the fate and transport oil spills in the Mediterranean Sea
based on MEDSLIK-II oil spill model forced by CMEMS and ECMWF fields.
Session: Ocean and marine services
The EMODnet MedSea Checkpoint
S. Simoncelli (1), N. Pinardi (1), G. Manzella, E. Moussat (2), E. Quinbert (2), F.
Blanc (3), G. Kallos (4), C. Kyriakid (5), L. Gomez-Pujol (6), G. Scarcella (7), A.
Cruzado (8), F. Falcini (7)
(1) INGV, (2) Ifremer, (3) CLS, (4) GUOA, (5) HCMR, (6) SOCIB, (7) CNR, (8)
OCEANS-CAT
The EMODnet MedSea Checkpoint aims at documenting the reliability and utility of the
existing monitoring system at the sea basin level, by developing fitness-for-use
indicators to show the adequacy of monitoring data for the production of Challenge
Targeted Poducts. The assessment criteria are subdivided into two territories:
• Availability pointing out how the input data sets are made available to the
users;
• Appropriateness showing the suitability of the input data to build the targeted
products.
There are seven Challenges: Wind Farm Siting (CH1), Marine Protected Areas (CH2),
Oil spill Platform Leaks (CH3), Climate and Coastal Protection (CH4), Fisheries (CH5),
Marine Environment (CH6) and Rivers (CH7). The assessment will help identify gaps
and prioritize the needs in order to optimize the monitoring system throughout the
value chain (i.e. data collection, in situ and satellite data assembling, data
management and networking, modelling and forecasting, geo-infrastructure) and
release recommendations for future developments to better meet the application
requirements.
The Checkpoint implementation requires the establishment of a CheckPoint
Information on upstream data (metadatabase) and a CheckPoint Service to
perform the assessment and make it available to the users.
The results of this novel methodology for the assessment of marine environmental
data will be shown.
50
8th International Workshop on Modeling the Ocean (IWMO)
Session: Ocean and marine services
Sea Conditions: present and future sea conditions for safer navigation
G. Coppini (1), P. Marra (2), R. Lecci (1), N. Pinardi (1,3) , S. Cretì (1), M. Scalas (2),
L. Tedesco (2), A. D’Anca (4), L. Fazioli (4), A. Olita(4), G. Turrisi (1), C. Palazzo (1),
G. Aloisio (1), S. Fiore (1), A. Bonaduce (1), Y. Kumkar (1), S. A. Ciliberti (1), I.
Federico (1), G. Mannarini (1), D. Rollo (2), A. Cavallo (2), A. Tumolo (2), T. Monacizzo
(2), M. Spagnulo (2) , R. Sorgente (4), P.Agostini (1), R. Bonarelli (1), S. Martinelli (1),
A. Cucco (4), M. Tonani (6), M. Drudi (6), L. Panzera (1), A. Navarra (1), G. Negro (2)
(1)Fondazione Centro Euro-Mediterraneo sui Cambiamenti Climatici, Ocean Predictions
and Applications, Lecce, Italy, (2)Links Management and Technology, Lecce, Italy (3)
Università degli Studi di Bologna, Italy, (4)Fondazione Centro Euro–Mediterraneo sui
Cambiamenti Climatici, Advanced Scientific Computing, Ecotekne Lecce, Italy,
(5)Consiglio Nazionale delle Ricerche – Istituto per l’Ambiente Marino Costiero,
Oristano, Italy, (6)Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy
Sea Situational Awareness (SSA) is strategically important for management and
safety purposes of Mediterranean Sea and its coastal areas. The lack of adequate
dissemination of marine environmental data and consequent poor knowledge available
for operations at sea reduce the response capacity, leading to loss of lives and
potential socio-economic damages. In the framework of "TESSA" project (industrial
research project funded under the PON "Ricerca&Competitività 2007-2013" program
of MinisteroItalianodell’Istruzione, dell’Università e dellaRicerca) the partners have
developed new SSA services and in particular this paper present “SeaConditions”, a
public service providing ocean and weather forecasts for the Mediterranean Sea, on
the web and mobile applications. Every day, forecasts and satellite products are
produced by operational services, such as the Copernicus Marine Environment
Monitoring Service (http://marine.copernicus.eu) for the ocean variables and ECMWF
for the atmospheric variables (provided by Italian Meteorological Office - CNMCA). In
additionbathymetry (providedby Istituto Idrografico della Marina, IT) and sealevel
(Istituto Superiore per la Protezione e la Ricerca Ambientale, IT) derivedproducts are
delivered. The service provides detailed information with high spatial and temporal
resolution. Products are displayed on Google Maps. Main products delivered on
SeaConditions are: weather and oceanographic forecasts, satellite ocean colour data
(chl-a and water transparency) and bathymetry. Ocean forecasts are given at
different resolution since nested area models for Mediterranean sub-regions are also
displayed.
SeaConditions provides a user friendly interface with zoom and drag Google Maps'
features allowing to display data with different levels of details. SeaConditions’ main
strength is to provide a single point of access to meteo-marine forecasts, which are
based on advanced oceanographic models, remote sensing products and bathymetry,
and to deliver high quality information.
The SeaConditions products are available through web and mobile channels. The web
portal www.sea-conditions.com is compatible with all modern web-browsers on all
51
8th International Workshop on Modeling the Ocean (IWMO)
operating systems. For the mobile users, APPs were also developed to consider the
different kind of screens and gesture/interactions. The APPs are available on
AppleStore and Google Play. Users’ feedback has been collected to improve the
service. Sea-Conditions mobile apps have been downloaded by more than 105.500,00
users and almost 100.000 users have visited the web version.
Session: Ocean and marine services
Drift simulation of MH370 debris using superensemble techniques
E. Jansen (1), G. Coppini (1) and N. Pinardi (2, 1)
(1) Euro-Mediterranean Center on Climate Change (CMCC), Lecce, Italy (2)
Department of Physics and Astronomy, Alma Mater Studiorum University of Bologna,
Bologna, Italy
Malaysia Airlines flight 370 (MH370) was a scheduled passenger flight that
disappeared on the 7th of March 2014 (UTC) while en-route from Kuala Lumpur in
Malaysia to Beijing in China. Less than an hour after take-off, air traffic control lost
voice and radar contact with the flight while it was over the Gulf of Thailand. Initially it
was assumed that the aircraft had crashed, but analysis of military radar data showed
that it had deviated from its planned flight path and returned towards Malaysia. It
continued flying in a west ward direction until itexited the radar coverage. Adding
further to the mystery, it was discovered that (minimal) communication between the
aircraft and the satellite network had continued until almost 7 hours after the
disappearance.
Based on the satellite data a rough trajectory of the plane was estimated, which
places the wreckage in an area of roughly one million square kilometres off the west
coast of Australia. Despite extensive search efforts in the past two years, the main
wreckage has not been found. The only parts of the aircraft that have been recovered
are a 2m piece of the right wing that was found on the island of Réunion; and two
smaller pieces of aircraft skin that were found in Mozambique.
This study presents a numerica lsimulation that uses high resolution oceanographic
and meteorological data to predict the movement of floating debris from the MH370
accident. A super ensemble isused, consisting of multiple model realisations that
represent different initial conditions and parameters. The realisations are weighted
based on theirpredictions for the discovered debris on Réunion and in Mozambique,
leading to a superensemble probability distribution that includes all of the available
data.
Using the superensemble, probabilitydistributions are generated for variouspoints in
time. The distribution at the initial time shows that the origin of the debris, and
therefore the location of the crash site, is most likely to be located below 30°S.
Results at later times show that the most probable locations to discover washed up
debris are along the Africaneast-coast and the southwest of Australia. The debris
remaining at sea from late 2015 is spread out over a wide area and its distribution
changes onlys lowly.
52
8th International Workshop on Modeling the Ocean (IWMO)
Poster Presentations
Performance Assessment for an Operational Ocean Model of the Taiwan
Strait
Yuwu Jiang, Xinyou Lin (1) , Zhencheng Zhang (1)
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen
361005, Fujian, P. R. China.
The Taiwan Strait Nowcast/Forecast System (TFOR), which is based on the Regional
Ocean Modeling System, may be the first operational ocean model to include both tide
and circulation processes in the Taiwan Strait. In this study, we assessed the
performance of TFOR by investigating the differences between observational data and
the results obtained by TFOR, thereby illustrating the ability of TFOR to reproduce
significant physical processes. Base on this model a nested Xiamen Bay coastal model
and a NPZD Ecosystem model is developed. We also evaluated the utility and
reliability of TFOR products for successful applications in maritime search and rescue.
Numerical study on the response of phytoplankton dynamics to various
atmospheric forcing in the Baltic Sea
Agata Cieszyńska
Institute of Oceanology of the Polish Academy of Sciences
The work, which is to be presented, focuses on numerical modeling of various
atmospheric forcing conditions and their influence on phytoplankton production and
vertical distribution of biomass. There are a lot of different phytoplankton species
living in the area of interest – the Baltic Sea. Biological-physical coupling controlling
these microorganisms’ life cycles is complex and that is why difficult to quantify. The
best and probably only way to study the issue is applying a numerical modeling tool.
The results to be presented are based on 1D numerical simulations carried out with
Princeton Ocean Model merged with the Ecological Regional Ecosystem Model
(ERGOM, http://ergom.net/). ERGOM is a system developed for the Baltic Sea
research by German scientists from the Leibniz Institute for Baltic Sea Research in
Warnemünde. The sensitivity of sea physics and phytoplankton production to
atmospheric forcing has been studied by implementing various surface salinity flux
and wind stress scenarios. Surface salinity flux was determined as the difference
between the evaporation and precipitation rates at the air-sea interface. Numerous
simulations with different parameter’s values, real and synthetic but representative
ones, were set and run. The aim was to change environmental conditions in a
controlled manner in order to obtain extended data sets with the information about
the role of atmospheric forcing and profiles of water column salinity and temperature
in the interactions being investigated. Data for parameterization of atmospheric
forcing were determined based on data sets from National Centers of Environmental
Prediction (NCEP) and global atmospheric reanalysis – ERA-Interim – of European
Centre for Medium-Range Weather Forecasts (ECMWF) In this presentation the
53
8th International Workshop on Modeling the Ocean (IWMO)
summary of the results will be discussed. This work has been funded by the National
Centre of Science project (contract number: 2012/07/N/ST10/03485) entitled:
“Improved understanding of phytoplankton blooms in the Baltic Sea based on
numerical models and existing data sets”.
Impacts of eddy-mean flow decomposition on Lagrangian statistics in a
barotropic double-gyre model
Yu-Kun Qian (1), Shiqiu Peng (1)
(1)State Key Laboratory of Tropical Oceanography, South China Sea Institute of
Oceanology, CAS, Guangzhou, China
Synthetic particles are advected by a high-resolution flow output from a wind-driven
barotropic double-gyre simulation using MITgcm, in order to investigate the impact of
eddy-mean flow decomposition on Lagrangian statistics. The mean flow is usually
defined as a temporal-averaged flow over the entire period of integration or
observation whereas the eddy part is the remnant. Here such definition is generalized
by using a spatial or temporal low-pass filter. Then the mean flow is the low-passed
part and the eddy flow is the corresponding remnant with respect to the mean part.
Different eddy-mean flow decompositions yield different eddy flows. Then Lagrangian
statistics derived from different eddy flows are presented and discussed. It is found
that some of the statistics rely highly on the definitions of eddy-mean flow
decompositions (or scale separations).
54
8th International Workshop on Modeling the Ocean (IWMO)
The factors of seasonal and interannual variation of upwelling in the West
and Southwest off Hainan island
Poster
Yineng Li (1); Shiqiu Peng (1)
[email protected]
(1)State Key Laboratory of Tropical Oceanography, South China Sea Institute of
Oceanology, Chinese Academy of Sciences, Guangzhou, China
During the summer time, an upwelling dominates west and south west off Hainan
Island, which can be observed by means of satellite sea temperature images. The
mechanism, seasonal and annual variation of upwelling west and southwest off Hainan
Island are investigated using a 3-D high-resolution model. The sensitive experiment
results show that an anti-cyclonic circulation anomaly with strong tidal front west and
southwest off Hainan Island is induced in summer when tide is included. Results also
indicate that the annual variations of sea temperature front and upwelling west and
southwest off Hainan Island are affected not only by the variation of local stratification
but also the large scale circulation which carries the subsurface warmer water to the
region of the front and intensifies the front induced current. The results can explain
the significantly seasonal and annual variation of upwelling west and southwest off
Hainan Island.
Comparison of some well-known sediment transport models
Aleksandra Dudkowska, Gabriela Gic-Grusza
University of Gdańsk, Gdańsk, Poland
The wave-induced bedload transport and the spatial distribution of its magnitude in
southern Baltic coastal zone is estimated. The vicinity of Lubiatowo, Poland is chosen
as a representative part of Polish coast. In this area westerly winds dominate. Along
the section of the shore in the area of interest there are four permanent bars and one
occurring temporarily. The sediment is quite uniform with diameter D50 = 0.22mm.
According to the measurements conducted in the studied area (Pruszak and Zeidler,
1995) the longshore sediment transport under weak waves conditions, with breaker
height much lower than 1 m occurs only in the area up to 200 m offshore with a rate
of 5–8 kg/(m h). For waves with mean breaker height slightly below 1 m, sediment
transport rate varies between 5–30 kg/(m h). During storms the rate of sediment
transport reaches 100 kg/(m h) between shore line and fourth bar and decreases to
30 kg/(m h) about the fifth bar. Four models were studied and compared over a wide
range of bottom shear stress as well as wind-waves conditions: Du Boys (1879),
Meyer-Peter and Müller(MPM) (1948), Engelund and Hansen (1967), Ribberink
(1998). In order to estimate the water flow velocity related to the wind wave,
modelling was conducted for several wind conditions. In the whole Baltic Sea WAM
model (WAMDI Group, 1988) was used. In the coastal zone SWAN model was used
[Simulating WAveNearshore;Booij et al. (1996)]. Cross-shore distribution of
55
8th International Workshop on Modeling the Ocean (IWMO)
calculated bedload transport rate for westerly winds is consistent with earlier studies
and measurements. Values of transport calculated based on Ribberink formula are the
highest. Bedload transport values calculated based on the Du Boys and MPM are about
100 kg /(m h) between shore line and fourth bar and decreases about the fifth bar,
which is similar to the values defined for storm conditions. The results of different
models are similar. It leads to the conclusion, that the more important factor
impacting the values obtained is proper modeling of the flow velocity in the boundary
layer. Booij N., Holthuijsen L. H., Ris R. C. (1996). The SWAN wave model for shallow
water. Proceedings of the 25th International Conference on Coastal Engineering.
Orlando, USA. Du Boys, P., 1879. Le rhone et les rivieres a lit affouillable. Annales des
Pontset haussees18, 141-195. Engelund, F., Hansen, E., 1967. A monograph on
sediment transport inalluvial streams. TekniskForlag. Meyer-Peter, E., Müller, R.,
1948. Formulas for bed-load transport. In: Proceedingsof the 2nd Meeting, IAHR
Stockholm, Sweden. pp. 39-64. Pruszak, Z., Zeidler, R. B., 1995. Sediment transport
in various time scale.In:Proceedings of the 24th International Conference Coastal
Engineering1994, 1, New York: ASCE. pp. 2513- 2526. Ribberink, J., 1998. Bed-load
transport for steady flows and unsteady oscillatory flows. Coast. Eng. 34, 59-82. van
Rijn, L. C., 1993. Principles of Sediment Transport in Rivers, Estuariesand Coastal
Seas. Aqua Publications. WAMDI Group (1988). The WAM model – A Third Generation
Ocean Wave Prediction Model. J. Fluid Mech., 70, 113–126.
Hydrodynamic modeling of coastal seas: the role of tidal dynamics in the
Messina Strait, Western Mediterranean Sea
A. Cucco, G. Quattrocchi, A. Olita, L. Fazioli, A. Ribotti, M. Sinerchia, C. Tedesco and
R. Sorgente.
National Research Council, Institute for Coastal Marine Environment, Oristano, 09170
Italy
This work explored the importance of considering tidal dynamics when modeling the
general circulation in the Messina Strait, a narrow passage connecting the Tyrrhenian
and the Ionian Sea sub-basins in the Western Mediterranean Sea. The tides and the
induced water circulation in this Strait are among the most intense oceanographic
processes in the Mediterranean Sea. The quantification of these effects can be
particularly relevant for operational oceanographic systems aimed to provide short
term predictions of the main hydrodynamics in the Western Mediterranean sub-basins.
A numerical approach based on the use of a high resolution hydrodynamic model was
adopted to firstly reproduce both the tides propagation and the wind induced and
thermohaline water circulation within the Strait and surrounding areas and secondly
to quantify the role of the Strait dynamics on the larger-scale water circulation. The
obtained results confirmed the importance of a correct representation of the
hydrodynamics in the Messina Strait even when focusing on predicting the water
circulation in the external sea traits. In fact, model results show that tidal dynamics
deeply impact the reproduction of the instantaneous and residual circulation pattern,
waters thermohaline properties and transport dynamics both inside the Messina Strait
and in the surrounding coastal and open waters.
56
8th International Workshop on Modeling the Ocean (IWMO)
Effect of the current shear front on the suspended particluate matters
transport off eastern Shandong Peninsula
Yongzhi Wang(1),Lulu Qiao(2),Guansuo Wang(1)
The first institute of oceanography, SOA.(1) Ocean University of China(2)
Based on field data of water temperature, turbidity and suspended sediment
concentration in winter and numerical model results, suspended sediment transport
and deposition off eastern Shandong Peninsula were studied. In winter, water
turbidity off eastern Shandong Peninsula was well mixed vertically, due to the strong
northerly wind. Moreover, two strong shear current fronts were found on both sides of
the topset of the mud wedge off the Shandong Peninsula, which was respectively
generated by northward upwind compensation current along eastern Shandong
Peninsula in the middle and lower water depths, northward Yellow Sea warm current,
and southward coastal wind-driven current above the topset of the mud wedge. The
two strong shear current fronts prevented suspended sediments from the bottomset
of the mud wedge getting cross eastern Shandong Peninsula continental shelf
peripheral, which was helpful to form the omega-shaped mud wedge off eastern
Shandong Peninsula. However, the mud deposition could be decreased and pushed
landward due to winter storms, which may be related to the strengthening and further
westward shift of the Yellow Sea Warm Current.
57
8th International Workshop on Modeling the Ocean (IWMO)
Impact of the Sumjin River Runoff to the connected the Kwangyang and
Kangjin Estuarine System, South Sea, Korea
Young Jae Ro and Baek Jin Kim
Dept. of Oceanography, College of Natural Sciences, Chungnam Natl. University, S.
Korea
The study area encompasses complicated networks of Sumjin River, Noryang(NR),
Yeosu(YS), Daebang(DB), Changson(CS) Channels. The NR channel is narrow and
relatively deep and is famous for its high tidal current speed exceeding 4 m/s. The
objectives of this study are that 1) budgeting the volume transport across each
channels, 2) circulation patterns with varying river runoffs, 3) residual current
distribution and its implications. Series of numerical modeling experiments were
carried out to understand the tidal circulation in the Sumjin River, KY Bay, and KJ Bay
estuarine system (SKY), South Sea of Korea. The tidal circulation in the SKY is mostly
controlled by the inflow from two channels, YS and DB which introduce the open
ocean water into the northern part of the SKY with relatively strong tidal current,
while in the southern part of the SKY, shallowest region of the entire study area, weak
tidal current prevails. The model performance is evaluated as satisfactory based on
the skill scores. Skill scores for the four major tidal constituents (M2, S2, K1 and O1)
exceeded 90 %. The budget for the volume transport across the four major channels
in the SKY system is of major interests. Table 1 lists those transports during flood and
ebb phases. Through the YS Ch., the biggest transport occurs with 22,442 (m3/s) at
flood phase which account for 69.8 (%) of the total inflow and the other two DB and
CS Channels account for the remainders of 30.2 (%). At ebb phase, transport of the
outflow across the Yeosu Ch. is 21667 (m3/s) which account for 67.5 (%) of the total
outflow. There exists an imbalance of transport across the YS Ch. between flood and
ebb phases. This imbalance is compensated by the net outflow across the DB and CS
Channels. The imbalance indicates a very important fact that mostly, net-inflow
occurs through the YS Ch. and net-outflow occurs through the DB Ch. passing through
the NR Ch. The orientations of the tidal ellipses show parallel with the local
bathymetry. Budget analysis for the water volume transport across four major
channels show that 70 % of total transport occurs through the Yeosu Channel. The
distribution pattern of the tidal residual current in the SKY with magnitude on the
order of a few cm/s shows correlated with the generation of small-scale eddies.
Persistent small scale eddies in the SKY are associated with the tidal residual current
and are commonly found in the regions with curved coastline and steep depth change.
58
8th International Workshop on Modeling the Ocean (IWMO)
Numerical Study of Seasonal Circulation and Variability in the Abandoned
Yellow River Estuary and Adjacent Coastal Waters
Xiaomei Ji (1), Jinyu Sheng(2)
(1)Hohai University (2)Dalhousie University
The abandoned Yellow River delta in northern Jiangsu Province, China is a typical
erodible silty and muddy coast which has been undergoing severe coastal erosion
since 1855 when the Yellow River diverted directly into Bohai Sea. This study
examines seasonal circulation, hydrography, and associated spatial variability over the
abandoned Yellow River Estuary and its adjacent coastal waters using a nested-grid
coastal ocean circulation model. The model external forcing consists of tides,
atmospheric forcing, and open boundary conditions based on the global ocean
circulation and hydrography reanalysis produced by the Hybrid Coordinate Ocean
model. Four numerical experiments are conducted with different combinations of
external forcing functions to examine main physical processes affecting the seasonal
circulation in the study region. In winter, the strong northerly winds drive southward
flow at the surface and along the coast. This is compensated by a northward return
flow at depth. The wind generated turbulence enhances deep cooling by thermal
convection. In summer, the weaker and less persistent winds from the south drive
northward and eastward flow along the coast. Local enhancements may be expected
due to tidal rectification, freshwater inputs and tidal mixing fronts. The winds combine
with surface heating to result in very strong thermal stratification, isolating the
bottom water.
Ability of a subset of CMIP5 to reproduce the sea surface temperature of
tropical Atlantic
S.C. Kenfack
Department of Physics, Mesoscopic and Multilayers Structures Laboratory, Faculty of
Science, University of Dschang, P.O.Box: 479 Dschang, Cameroon.
The neural network model has been performed on the Principal Component Analysis
(PCA) to obtain nonlinear principal component analysis (NLPCA), which allows the
extraction of nonlinear features in the dataset missed by the PCA. This non linear
method is applied on detrended monthly Sea Surface Temperature Anomaly (SSTA)
data from the tropical Atlantic Ocean (30°W-20°E, 26°S-22°N) for the period 1950 to
2005. The objective is to compare the modes extracted through this statistical
analysis to those previously extracted through the more simple PCA. The focus is on
the differences between SST inter-annual variability patterns; either extracted
through traditional PCA or NLPCA methods. CMIP5 (Coupled Model Intercomparison
Project Phase 5) pre-industrial simulations are examined to assess the ability in
reproducing the El Niño, Atlantic dipole and Atlantic cold tongue (ACT) variability in
the Tropical Atlantic Ocean. We present results of PCA and NLPCA on the ERSST data
set from the NOAA and few models of CMIP5 model ensemble. It is observed that the
first NLPCA modes explain marginally more of the total data variance than do the PCA
modes. Our results show that a modest number of models were able to correctly
59
8th International Workshop on Modeling the Ocean (IWMO)
capture the meridional mode (Atlantic dipole). NLPCA shows that the spatial
distribution of the El Niño pattern signature in model HadGEM2-AO compares
reasonably well with the observed features but with sign reversal.
Response of tidal shear front to wind and its effect on suspended sediment
transport in the Yellow River Delta
Nan Wang(1)(2), Guangxue Li(1)(2), Lulu Qiao (1,2), Ping Dong(1)(2), Yi
Zhong(1)(2), Zhen Wang(1)(2)
(1) College of Marine Geosciences, Ocean University of China, Qingdao 266100, P. R.
China. (2) Key Laboratory of Submarine Sciences and Prospecting Techniques, MOE,
Ocean University of China, Qingdao 266100, P. R. China.
As a kind of estuarine fronts, tidal shear front is common in many estuaries around
the world. Its characteristic, generation, and variation have been studied in previous
works, and many influence factors have been considered, such as tidal dynamic,
topography, runoff, temperature, and salinity. However, a detailed investigation of
wind influence on tidal shear front has not been conducted. The aim of this study is to
use a three-dimensional sedimentary dynamic model to examine characteristic
changes of tidal shear front under the effect of wind and their effects on suspended
sediment transport in the Yellow River Delta. The results showed that wind had effects
on tidal shear front in length, shear strength, and duration by shallow wind-driven
flow and the characteristic changes had a near liner correlation with wind velocity.
Especially in extreme weather event, strong wind can greatly change tidal shear front
even break it. In consideration of the topography and tidal current direction in the
delta, the north wind increased IFOE (inner-flood-outer-ebb) type shear front, but
decreased IEOF (inner-ebb-outer-flood) type shear front, and vice versa. Based on
sensitive numerical experiments, re-suspended sediment flux and SSC distribution
range greatly increased during strong wind weather event are partly caused by shear
front variation, as restriction of shear front to suspended sediment transport was
weaker than general situation. In the Yellow River delta, this process could be a new
supplementary explanation in mechanisms of seasonal suspended sediment transport
variation besides wave and tidal current.
A modelling study of the Antarctic Circumpolar Current dynamics in the
Southern Ocean sector south of Australia and New Zealand, including the
Ross Sea
Paola de Ruggiero (1), Stefano Pierini (1), Giovanni Sgubin (2)
(1) Dipartimento di Scienze e Tecnologie, Università di Napoli Parthenope, Napoli,
Italy (2) Environnements et PaléoenvironnementsOcéaniques et Continentaux (EPOC),
Universite de Bordeaux, Pessac, France
A modelling study of the Antarctic Circumpolar Current dynamics in a wide sector of
the Southern Ocean (SO) is presented. A sigma-coordinate ocean model with a spatial
resolution of 0.18° and 15 vertical sigma levels is implemented in a domain extending
meridionally from 29.83°S to 80°S and longitudinally from 90°W to 110°W with
periodic boundary conditions. Thereby the region includes the SO sector south of
60
8th International Workshop on Modeling the Ocean (IWMO)
Australia and New Zealand, as well as the Ross Sea. We performed simulations with
both idealized and realistic atmospheric boundary conditions. Idealized but relatively
realistic climatological oceanic stratification, and surface momentum and heat fluxes
have been first imposed to identify and analyse cases of intrinsic oceanic variability,
thus extending to this SO sector a previous modelling study focused around the Drake
Passage (Sgubin, Pierini and Dijkstra, Ocean Sci. 9, 201-213, 2014). A more realistic
implementation makes use of the Southern Ocean Database (SODB) for the
initialization and of the ERA-Interim ECMWF modelling data for the atmospheric
forcing. Model validation is being carried out with altimetric data and with in situ
observations obtained by the Programma Nazionale di Ricerche in Antartide (PNRA).
This work was carried out in the framework of the ACCUA project of the PNRA
managed by CoNISMa.
Operational modeling issues in extreme weather coastal flooding
D. Di Luccio (1), G. Benassai(2), G. Budillon(1), Angela Di Leo(3), R. Montella(1), E.
Pugliese Carratelli(4), F. Reale(4)
1) University of Naples “Parthenope”, Science and Technologies Department, Napoli,
Italy (2) University of Naples “Parthenope”, Engineering Department, Napoli, Italy (3)
University of Salerno, Civil Engineering Department, Salerno, Italy (4) Inter-University
Consortium for the Prediction and Prevention of Major Risks Hazards, Salerno, Italy
The coastal environment is a highly complex dynamic system, influenced by natural
and human factors that contribute to its spatial and temporal evolution. Specifically,
the South Tyrrhenian Sea and in particular the Campania coastal area, is heavily
affected by human activities and extreme weather/marine events can cause extensive
landscape, as well as social and economic damage. The work presented here is aimed
at developing a real time system to forecast and manage the potential risks for
citizens and infrastructure deriving from extreme sea storms. It originated as part of a
project funded by the Municipality of Naples and is now being extends in methods and
scope by the University of Naples “Parthenope” and by C.U.G.RI. (Inter-University
Consortium for the Prediction and Prevention of Major Hazards). The objectives are
achieved by making use of a high spatial resolution weather-ocean forecasting system
for the south Tyrrhenian sea implemented by CCMMMA (Campania Center for Marine
and Atmospheric Monitoring and Modelling, University of Naples “Parthenope” –
meteo.uniparthenope.it) using a high performance computing system to manage and
run a modeling chain based on the open-source numerical models WRF (Weather
Research and Forecasting) and WW3 (Wavewatch III). A newly developed software
system implements the mathematical solver which compute the wave transformation
from the off-shore computational grid points down to the coast, with the final goal of
forecasting the run-up and overtopping parameters on the beaches and on the coastal
infrastructures. Although the proposed system is currently being tested and calibrated
in order to improve its reliability, the scientific and technological results produced so
far have been routinely used as a decision support tools by the local authorities Bay of
in Naples governing and by beach resort managers in the case of extreme sea storm
events.
61
8th International Workshop on Modeling the Ocean (IWMO)
FairWind: a marine data crowdsourcing platform based on Internet of Things
and mobile/cloud computing technologies.
Raffaele Montella, Carmine Ferraro, Diana Di Luccio, Federica Izzo, Pasquale
Troiano, Giulio Giunta
In the field of ocean modeling the need for computational and storage resources is
currently satisfied by the availability of cloud based services that reduce the total cost
of ownership and accelerate accelerate the democratization of science. Nevertheless,
to have more robust and accurate models, there is a need for detailed, high
resolution, spatio-temporal data for initialization and validation. While data can be
hard to obtain from traditional sources, due the lack of available public data in some
coastal areas, the challenges of surveying large areas and other technical constraints,
this data can be easily obtained using the crowdsourcing tools like Fairwind. The
astonishing growth of technologies related to pervasive computing enables applied
research in marine science and engineering to take advantage of the recent rise of the
internet of things and mobile/cloud computing. While crowdsourcing is widely used in
many diverse science fields, applications to marine environmental research remain
largely unexplored. FairWind is an integrated, multifunctional, navigation software
based on open technologies designed and developed by a very interdisciplinary team
in order to maximize the benefits and the advantages. It is a marine single board
computer device leveraging a custom-built infrastructure on top of stable and welldocumented mobile and cloud technologies. From the marine electronics point of view,
the most remarkable innovations introduced by FairWind are the Boat Apps that
extend the FairWind basic features, integrating with already present onboard
instruments and straightforwardly interacting with industrial or self-made internet of
things based instruments. The board dataset, collected by FairWind, is a scientifically
intriguing source of huge amounts of geolocated data (big-data) about marine coastal
environment (weather and sea conditions, surface sea currents, water temperature,
water depth, etc.), boat engine status, boat performances (speed, heading, pitch,
roll), presence of board water and waste management, fuel consumptions and, above
all, safety at sea and search and rescue systems. Data is collected on board and,
when possible, then sent to cloud storage and computing facilities using reliable,
affordable, and safe technologies such as the Globus data transport services. Users
can choose what data to share in a named or anonymous way. Operationally, once
data is collected, will be analyzed and processed in order to extract sensor calibration
using big-data algorithms, evaluated with a quality model comparing it with data
acquired by thrustful equipment and, finally, made available as open data for ocean
model initialization and/or validation.
62
8th International Workshop on Modeling the Ocean (IWMO)
WaComM: a hierarchically parallel lagrangian Water quality Community
Model integrated in a workflow data science portal.
Raffaele Montella (1,4), L. Baldi (2), Stefania Cavallo (2), Germana Colarusso (2),
Maurizio Della Rotonda (4), Diana di Luccio (1), Carmine Ferraro (1), Angelo Riccio
(1), Paolo Sarnelli (4), Pasquale Troiano (1), Alison Brizius (5)
Mussel farm quality is one of the outstanding issues in current operational marine
science. In order to evaluate the potential hazardous substances (chemicals or
biological) continuously or spottily spilled in the marine environment, a robust, stable
and consistent operational forecast system is needed. Such a system would require i)
the management of diffuse and point pollution sources, ii) the ability to scale in terms
of domain size and and iii) the computational performance and effectiveness needed
to provide results for decision support. The above mentioned constraints drove the
design and the implementation of WaComM (Water quality Community Model), a three
dimensional decision support model enabling the simulation and the prediction of
pollutant spills, transport and dispersion in both inshore and offshore environments.
WaComM uses a hybrid approach, based on Eulerian-Lagrangian models, providing a
qualitative and semiquantitative tool for human health risk assessment. WaComM
could be used in an ex-ante fashion, as decision support tool to aid in the selection of
the best suitable areas for human activity deployment, and in an ex-post fashion, in
order to achieve a better management of offshore human activities. WaComM
improves upon previous experiences with three dimensional lagrangian assessments
for marine pollution thanks to the development of i) deep-algorithms’ optimization to
increase efficiency and effectiveness on High Performance Computing (HPC)
environment (X86_64 and IBM P8 architectures) and ii) the implementation of novel
restart feature. WaComM has been integrated into the Framework to Advance
Climate, Economic, and Impact Investigations with Information Technology (FACE-IT),
a workflow engine and data science portal based on Galaxy and Globus technologies.
FACE-IT Galaxy is an integrated data pre/post processing and simulation framework
that supports all the model offline coupling workflow in order to produce operational
predictions about the impact of pollutants spilled out from both natural and anthropic
sources in mussels farming high density areas. Using FACE-IT WaComM can be
directly coupled ROMS (Regional Oceanic Modelling System) and WRF (Weather
Research and Forecast) leveraging on high-performance and cloud computing
resources to enable fast full system modeling.
Tackling extreme bloom events in the Mediterranean Sea with the MITgcmBFM numerical model
Valeria Di Biagio (1), Gianpiero Cossarini (1), Stefano Querin (1), Stefano Salon
(1), Gianmaria Sannino (2), Cosimo Solidoro (1)
Valeria Di Biagio (1), Gianpiero Cossarini (1), Stefano Querin (1), Stefano Salon (1),
Gianmaria Sannino (2), Cosimo Solidoro (1)
Extreme algal blooms in the Mediterranean Sea are investigated using the MIT
General Circulation Model coupled online with the Biogeochemical Flux Model, at a
63
8th International Workshop on Modeling the Ocean (IWMO)
resolution of 1/12°x1/12°, on 75 vertical levels. Daily chlorophyll fields are analyzed
together with oxygen, nutrients and the main physical variables, to characterize the
spatiotemporal distribution of the blooms, at the surface and in the whole photic
layer. A proper definition of extreme blooms has been developed from the
spatiotemporal probability density functions of the phytoplankton chlorophyll,
considering peaks over thresholds, dependent on the spatial location and the two
ranges of depth. Preliminary results from a short run (years 1979-1985) are shown, in
view of a longer simulation (1979-2012), giving both a suitable statistics and a
climate value to the present study.
Decadal change of Antarctic Intermediate Water in the region of Brazil and
Malvinas confluence.
XiaoYi Yang(1,2) and Zhigang He (2)
(1) State Key Laboratory of Marine Environmental Science, Xiamen University.Xiang
an Campus, 361102, Xiamen, Fujian, China. (2) College of Oceanography and Earth
Sciences, Xiamen University.Xiang an Campus, 361102, Xiamen, Fujian, China.
The Antarctic Intermediate Water (AAIW) exhibits a decadal variability during recent
years, i.e., salinification before 1997 and freshening thereafter, with the maximum
anomalies locating at the region of Brazil and Malvinas currents confluence. Our study
proposed that the local mesoscale eddies may play an important role in triggering this
decadal oscillation. The eddy activity intensification (weakening) leads to the increase
(decrease) of poleward cross-frontal eddy salinity flux and upward eddy buoyancy
flux, which results in the weakening (strengthening) of the subsurface stratification
and potential vorticity (PV). The PV anomalies facilitate (block) the poleward transport
of warm saline subtropical water, while the stratification weakening favors the further
downward transmission of salinity anomalies by processes of eddy flux as well as
mean-flow advection (the stratification strengthening inhibits the vertical transport),
then initiates the decadal change of the AAIW property. The whole process of the
eddy-related propagation of salinity anomalies takes about 4 to 6 years.
Establish a 2D hydrodynamic and mass transports model based on the
SHYFEM.
Chen Zhaozhang, Hu Jianyu, Lin Hongyang, Zhu Jia, Sun Zhenyu
The Institute of Oceanography and Earth Science, Xiamen University
We simulate the distribution and variation of hydrodynamic and water reserving time
in the Sansha bay. The results are as following: 1) The model can well deal with the
complex bathymetric situations and geometries in Sansha bay. The calibration of the
model is good. The simulation value can well match the measured value. 2) Sansha
bay is famous for its strong tide, strong current and great prism. These tide
distribution characters are controlled by the bathymetry and geometry’s situation of
the bay. The strongest tidal current always happens at the deep waterways and the
narrow channels. The maximum current is more than 2m/s in Dongchongchannel . 3)
The water reserving time’s distributions relate to the distance from the bay mouth and
64
8th International Workshop on Modeling the Ocean (IWMO)
the tidal current. The water exchanging in the the bay mouth is faster than that in the
bayhead. The longest water reserving time is about 35 days in the bayhead.
Tide-and wind-driven variability of water level in Sansha Bay, Fujian, China
Hongyang LIN (1), Jianyu HU1, Jia ZHU (1), Peng CHENG (1),Zhaozhang CHEN (1),
Zhenyu SUN (1), and Dewen CHEN (2)
(1) State Key Laboratory of Marine Environmental Science, College of Ocean and
Earth Sciences, Xiamen University, Xiamen, Fujian 361102, China (2) Marine Forecast
Station of Xiamen, State Oceanic Administration 361012, China
This study analyzes water-level variability in Sansha Bay and its adjacent waters near
Fujian, China, using observed water-level data from seven stations along the coasts
and wind data observed from a moored buoy near Mazu Island. At super- to nearinertial frequencies, tides dominate the water-level variations, mainly characterized by
semi-diurnal(primarily M2, S2, N2) and diurnal tides(primarily K1, O1).The correlation
coefficients between residual (non-tidal)water-level time series and the observed
wind-stress time series exceed 0.78 at all stations, hinting that the wind acting on the
study region is another factor modulating the water-level variability. A cross-wavelet
and wavelet-coherence analyses further indicates (i) that the residual water level at
each station is more coherent, and out-of-phase, with the alongshore winds mostly at
sub-inertial time scales associated with synoptic weather changes, and (ii) that the
residual water-level difference between the outer and inner bay is more coherent with
the cross-shore winds at discrete narrow frequency bands, with the wind leading by a
certain phase. The analysis also implies that the monsoon relaxation period is more
favorable for the formation of land-sea breeze, modulating the residual water-level
difference.
A regional ocean model for the Black Sea within the frame of the Copernicus
Marine Environment and Monitoring Service
S.A. Ciliberti, (1), Peneva, E. (2), Storto, A. (1), Lecci, R. (1), Coppini, G. (1),
Masina, S. (1) Pinardi, N. (1,3)
(1) Centro Euro-Mediterraneo sui Cambiamenti Climatici CMCC Foundation, Ocean
Predictions and Applications (OPA) Division, Lecce, Italy, (2) Sofia University "St.
Kliment Ohridski" (Bulgaria), (3) Department of Meteorology and Geophysics, (3)
University of Bologna (Italy), Department of Physics and Astronomy
A new numerical regional ocean model for the Black Sea has been developed to
support the Black Sea Monitoring and Forecasting Center (BS-MFC), a novel system
within the constellation of Copernicus Marine Environment Monitoring Service
(CMEMS, http://marine.copernicus.eu). The CMEMS service is going to provide regular
and systematic information about the physical state of the ocean and marine
ecosystems for the Black Sea. The numerical model implementation with data
assimilation and based on NEMO v3.4 (Madec et al., 2012) has been designed and
maintained operational since January 2016 at CMCC (Ciliberti et al, 2016). The Black
Sea domain is resolved with 1/27° x 1/36° horizontal resolution (~3km) and 31 zlevels with partial steps based on the GEBCO bathymetry data (Grayek et al., 2010).
65
8th International Workshop on Modeling the Ocean (IWMO)
The exchange with the Mediterranean Sea is represented through the Bosporus Strait
as surface boundary condition, taking into account the calculated barotropic transport
to balance the freshwater fluxes on monthly basis (Stanev and Beckers, 1999; Peneva
et al., 2001). Every day the Black Sea forecasting system produces 10-days forecast,
3-day analysis and 1-day simulation. Once per week, the system is restarted 15-days
earlier in analysis mode, using a three-dimensional variational data assimilation
system (Storto et al., 2014), to compute the new optimal initial condition for the
forecast cycle. Products, such as hourly and daily mean temperature, salinity, currents
and
sea
surface
height
with
online
validation,
are
available
on
http://oceanlab.cmcc.it/blacksea/.
References
• Ciliberti, S.A., Peneva, E., Storto, A., Rostislav, K., Lecci, R., Yang, C., Coppini, G., Masina, S., Pinardi,
N., 2016. Implementation of Black Sea numerical model based on NEMO and 3DVAR data assimilation
scheme for operational forecasting, Geophysical Research Abstracts, Vol. 18, EGU2016-16222, 2016.
• Grayek, S., Stanev, E., Kandilarov, R., 2010. On the response of Black Sea level to external forcing: altimeter data and numerical modelling. Ocean Dyn. 60, 123–140.
• Madec, G., and the NEMO Team, 2012. NEMO ocean engine version 3.4. Note du Pole de la Modelisation
de l'Insitut Pierre-Simon Laplace, No 27 ISSN no 1288-1619
• Peneva, E. L., E. Stanev, V. Belokopytov, and P.Y. Le Traon, 2001. Water transport in the Bosporus
Straits estimated from hydro-meteorologycal and altimeter data: Seasonal to decadal variability. J. Mar.
Sys., 31, 1-3, 21-35.
• Stanev E. and J.M. Beckers, 1999. Barotropic and baroclinic oscillations in strongly stratified ocean
basins: Numerical study of the Black Sea. Journal of Marine Systems, 19, 65–112.
• Storto A., Masina S., Dobricic S., 2014. Estimation and impact of nonuniform horizontal correlation
length scales for Global Ocean physical analyses. J. Atmos. Ocean. Technol., 31: 2330-2349.
Characteristics of mesoscale eddies in the Subtropical Southeast Indian
Ocean
Wei Zhuang (1), Ming Feng (2)
(1) State Key Laboratory of Marine Environmental Science, Xiamen University,
Xiamen, China, (2) CSIRO Marine and Atmospheric Research, Floreat, Western
Australia, Australia
This study describes the characteristics of mesoscale eddies in the subtropical
southeast Indian Ocean (IO) based on the multi-satellite observations, the Argo data
and the output of an eddy-resolving model. There are strong eddies activities near the
western Australian (WA) coast and in the interior IO basin. Eddy generations are the
most active near the WA coast. On average, the nearshore eddies propagate about
400 km westward and thus have minor impact on the open ocean EKE variability. The
EKE pattern in this region is largely determined by eddy amplitudes rather than eddy
numbers or other eddy parameters. Furthermore, the eddy variability results in
significant heat and freshwater transports and modulates the mesoscale chlorophyll
distributions in the subtropical southeast IO.
66
8th International Workshop on Modeling the Ocean (IWMO)
Reversal process of the South China Sea western boundary current in autumn
2011
Jingsong GUO, Zhixin Zhang, Fangli Qiao
First Institute of Oceanography, SOA, China
Using merged sea level anomaly and absolute geostrophic velocity products from
satellite altimetry and Argos drifter data, we analyzed the reversal process of the
South China Sea (SCS) western boundary current (SCSwbc) from a summer to winter
pattern in 2011 and important oceanic phenomena during this process. Results show
that the outbreak time of the northeast monsoon over the southern SCS lagged that
over the northern SCS by about 1 month. During the SCS monsoon reversal period,
the SCSwbc reversed rapidly into the winter pattern at the Guangdong continental
slope in late September. Subsequently, the southward Vietnam coastal boundary
current strengthened. However, the northward Natuna Current maintained a summer
state until mid-October. Thus, the balance between the southward and northward
currents was lost when they met, their junction moved gradually southward. However,
a loop current formed southeast of Vietnam because the main stream of the Vietnam
Offshore Current (VOC) remained near its original latitude. Meanwhile, the VOC and
associated dipole circulation system strengthened. After mid-October, the northward
Natuna Current began to weaken, the loop current finally shed, becoming a cool ring.
The VOC and its associated dipole sub-basin circulation system also weakened
gradually until it disappeared.
Roles of island chains on the Kuroshio intrusion in the Luzon Strait
Zhida Huang (1), Hailong Liu (2), Pengfei Lin (2), Jianyu Hu (1), *
(1)State Key Laboratory of Marine Environmental Science, College of Ocean and
Earth Sciences, Xiamen University, Xiamen 361102, China.
(2)State Key Laboratory of Numerical Modeling for Atmospheric Sciences and
Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), Chinese
Academy of Sciences, Beijing 100029, China.
Based on the global oceanic general circulation model LICOM 2.0 developed by
LASG/IAP, with high resolution of 0.1°, we run four numerical experiments to
estimate roles of the island chains on the Kuroshio intrusion into the Luzon Strait
(LS). In these experiments, the island chains in the LS are devided into three parts,
i.e., the southern part of the island chains (south of Babuyan Island), the middle part
of the island chains (north of Babuyan Island) and the Babuyan Island. Combing with
the satellite altimeter products from AVISO and the sea surface temperature from
OISST during 1993−2007, and the climatological temperature and salinity from
WOA13, we compare the differences between these experiments and observations.
When all the island chains are well presented in the model, the surface geostrophic
currents and temperature are consistent with observations. When parts of the island
chains are missed, large distinctions exist between model results and observations. It
67
8th International Workshop on Modeling the Ocean (IWMO)
can be concluded that: (1) The southern part of the island chains decreases the inflow
angle measured from the positive x-axis while the Kuroshio intrudes the LS, which
leads the Kuroshio strong enough to overcome the β effect, and so the Kuroshio tends
to leap the LS easily. (2) The middle part of the island chains makes parts of the
Kuroshio water flow northward, while the Kuroshio mainly leaps the LS. (3) The roles
of the Babuyan Island are the increase of inflow angle and the decease of inflow
speed, which lead the Kuroshio not strong enough to overcome theβeffect and thus
increase the westward bending of the Kuroshio. Analysis also demonstrates that the
LS volume transport decreases as much as 17% if the island chains are not well
presented. Therefore, the island chains have key roles on the Kuroshio intrusion into
the LS.
The sensitivity of typhoon forecasting to surface wave and rainfall
Biao Zhao; Fangli Qiao; Luigi Cavaleri; Guansuo,Wang; Luciana Bertotti; Li Liu
First Institute of Oceanography (FIO) under State Oceanic Administration (SOA),
China
An Atmosphere-Ocean-Wave regional coupled model has been developed by the First
Institute of Oceanography (FIO-AOW). The FIO-AOW includes four components: an
atmosphere model (WRF), an ocean model (POM), a wave model (MASNUM-Wave)
and a coupler (C-Coupler). The sensitivities of typhoon intensity to the physical
processes at the air-sea interface are evaluated using FIO-AOW. Three processes are
investigated in this paper: sea spray, non-breaking wave-induced vertical mixing and
cooling effects of rain. It has been found that sea spray could increase air-sea
moisture and heat flux, providing more vapor and thermal energy for typhoon to
strengthen its intensity. Therefore, sea spray has a positive effect on typhoon
intensity. While, non-breaking wave-induced vertical mixing could enhance upperocean vertical mixing rate and result in sea surface temperature (SST) cooling, which
in turn prevent typhoon getting more energy from ocean. Rain drops would evaporate
and lose heat when falling from high altitude to sea surface, thus cooler and lighter
fresh water will remain on sea surface and result in SST cooling, thus decrease
upward surface heat fluxes from ocean. Both wave mixing and rain have negative
effects on typhoon intensity. For the strong typhoon case Haiyan, the sea spray effect
is dominant over the negative effects of wave mixing and rain. The combined effects
of the three processes tend to strengthen and improve the typhoon intensity.
However, the typhoon dimensions have been exaggerated by all the experiments even
in control run. For the weak typhoon case Jebi, the effect of wave mixing is much
more significant relatively. The negative contribution of non-breaking wave induced
mixing to the total upward heat flux are comparable with the positive contribution of
sea spray, considering wave mixing scheme and cooling effects of rain prevents Jebi
from further deepening. As well as Haiyan, all the experiments tend to exaggerate the
dimensions of Jebi. The numerical results of this study indicate that the physical
processes at air-sea interface should be one of the critical factors in improving
prediction of typhoon intensity.
68
8th International Workshop on Modeling the Ocean (IWMO)
Three-Dimensional Hydrodynamics, Sediment and Water Quality Model for
Estuaries
Q.F. Zhu (1), Y.W. Jiang (1), Z.W. Wan(2), Onyx W.H. Wai(3)(1)State Key
Laboratory of Marine Environmental Science (Xiamen University), China; (2) Danish
Meteorological Institute, Denmark; (3) Department of Civil and Structure Engineering,
the Hong Kong Polytechnic University, Hong Kong, China
A parallel three-dimensional (3D) finite element model with drying and wetting
processes has been developed for hydrodynamics, sediment and water quality
simulation. This model makes lots of techniques to be more accuracy and efficient. In
order to perform accuracy simulation, the
model uses 2-order shape function and 6node triangular element to discretize the research domain. Within one computation
time step in the model, the technique makes use of an explicit Eulerian-Lagrangian
scheme、finite element method (FEM) and voronoic finite volume method (FVM) to
handle the momentum equation and continuity equation, respectively.
Comparison of typhoon-induced near-inertial oscillations in shear flow in the
northern South China Sea.
SUN Zhenyu (1), HU Jianyu (1), ZHENG Quanan (2), GAN Jianping (3)
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen
361102, China (2)Department of Atmospheric and Oceanic Science, University of
Maryland, College Park, Maryland 20742, USA (3) Department of Mathematics and
Atmospheric, Marine and Coastal Environment Program, Hong Kong University of
Science and Technology, Kowloon, Hong Kong.
With moorings equipped with Acoustic Doppler Current Profilers (ADCP) in the
northern South China Sea (SCS) in 2008 and 2009, we observed three near-inertial
oscillation (NIO) events coded 2008a, 2009a and 2009b induced by passages of
typhoons or tropical storms. This study compares characteristics of the three NIO
events. Event 2008a was the strongest one among the three, and had the longest
sustaining period (15 d), while events 2009a and 2009b sustained for only 4 and 8 d,
respectively. The three events were distinguished by vertical energy distribution and
phase propagation. As for the frequency shift of the NIO, event 2008a had a peak
frequency lower than the local Coriolis frequency (red-shift), while events 2009a and
2009b showed blue-shift.The behavior of individual NIO event is jointly decided by the
typhoon disturbance and the background ocean condition. Especially the background
flow plays an important role by effects of advection and modulation. The results in this
study provide observational evidence of variationalNIO response to background flow
field.As indicated by the distribution of vorticity and effective Coriolis frequency
derived from numerical modeling, the large amplitude and elongated sustaining period
of event 2008a were attributed to the waveguide effect of the background shear flow.
This effect redistributed the NIO energy after the typhoon passage, absorbed incident
waves and trapped energy in the area of the negative vorticity. While the background
flow during events 2009a and 2009b did not have such effects due to the near-zero
vorticity in the mooring area.
69