Download OCEAN-ATMOSPHERIC INTERACTION IN THE SUBTROPICAL

1. Ocean-Atmospheric Interaction in The Subtropical North
Pacific and Its Effect On Climate Variation
Prof. Liu Qinyu, Physical Oceanography Lab. & Ocean-Atmosphere Interaction
and Climate Lab., Ocean University of Qingdao, 5 Yu Shan Road, Qingdao
266003, China
Email: [email protected]
The atmospheric forcing to the ocean is the main external forcing to the low-frequency
variability of the Subtropical North Pacific. The forcing is in the form of air-sea boundary
fluxes, i.e. momentum flux and buoyancy flux. Clear understanding of physical processes of
the subtropical Pacific air-sea interaction and quantitatively description of the processes are
premise and basis for the study of the subtropical gyre. In the Subtropical North Pacific the
timescale of the atmospheric variability is short, however, the spatial variability of SST is
large. This means rapid-change atmosphere above very non-uniform SST such as the
Kuroshio and subtropical fronts. Hence, the air-sea interaction in the subtropical ocean is
different from that in the tropical. Though the possibility of the existence of air-sea
interaction in the mid latitude was suggested long time ago (Namias1974), the relatively
small evaporation, large mixed layer depth and large Coriolis effect in the extra tropics and
ITCZ in the North Pacific result in different character of wind-evaporation-SST feedback in
the subtropical and tropical North Pacific Ocean. Bjerknes(1962) suggested that the air-sea
interaction in the mid latitude is single direction, i.e., the atmosphere forcing the ocean and
no strong feedback of SST anomaly on the atmosphere. The issue on the air-sea interaction in
the mid latitude has been disputed. For a long time, the progresses on studying the subtropical
air-sea interaction were very slowly. The subject has gained attention again since the Pacific
Decadal Oscillation (PDO) was found, and the northern part of subtropical gyre (40ºN, 170º
W) is one of the PDO centers. Recently, we revealed that the air-sea interaction by
wind-evaporation-SST feedback sustains the influence of the Hawaiian Islands topography on
the atmosphere and ocean over a long stretch to the west of the islands (Xie. S. P. et al. 2001).
However, the study was limited to the ocean west of the Hawaiian Islands. The knowledge of
temporal and spatial distribution of momentum flux and buoyancy flux and
wind-evaporation-SST feedback in the whole subtropical ocean is very less.
In this project, we are going to analysis dominant physical processes and climate effects of
the ocean-atmosphere interactions in subtropical North Pacific based on the observation data
and numerical model. To study the follows topics: Mechanism of wind-evaporation-SST
feedback near the temperature front in the subtropical; Character and mechanism of air-sea
interaction near the Kuroshio extension; Interannual and interdecadal variability of air-sea
flux in the North Pacific and its effect on the Globe climate
References:
Bjerknes, J., 1962:Synoptic survey of the interaction between sea and atmosphere in the
North Atlantic Ocean. J. Climate, 8, 3067-3083
Namias, J., 1974, Longevity of a coupled air-sea-continet system. Mom. Wea. Rev, 102,
638-648.
Xie S.P., W．T. Liu, Q. Liu, and M. Nonaka, 2001,Far-Reaching Effects of the Hawaiian
Islands on the Pacific Ocean-Atmosphere System SCIENCE ， Vol.292, (No.5524),
2057-2060
2. MM5 Simulations of the 1 August 2001 Extratropical Cyclone
accompanied with Heavy Precipitation over Shandong Peninsula.
Dr. Gao Shanhong, Professor Wu Zengmao, Institute of Physical Oceanography, Ocean
University of Qingdao, 5 Yushan Road, Qingdao 266003, P. R. China.
Email: [email protected], [email protected]
A considerable part of tropic cyclones can transform to extra tropical cyclones under
certain weather conditions after they move northward to mid-latitude ocean area. Tropic
cyclones generated in the Northwestern Pacific have two main areas to transform to extra
tropical cyclones. One area is Japan Sea, and the other is the ocean area along the coast of the
eastern China. In the latter the 1 August 2001 extra tropical cyclone suddenly developed from
a low pressure left by Typhoon Taraji, which produced heavy precipitation and resulted in
centennially flooding. NCAR-PSU mesoscale model MM5 was applied to study why the
extra tropical cyclone developed so rapidly and the rainfall amount was so large. A series of
MM5 simulations (including two control experiments and several sensitivity experiments)
were completed. The evolution of the extra tropical cyclone and its heavy precipitation was
successfully modeled by control experiments, and sensitivity experiments indicated that
latent heat release played a very important role, and that plentiful moisture and high sea
surface temperature were the two key factors contributed to the development of the extra
tropical cyclone and its accompanying heavy precipitation over Shandong Peninsula.
3. THE VARIABILITY OF PACIFIC SUBTROPICAL CELLS
AND ENSO
Dr. Wang Q I, Professor, Department of Marine Meteorology, Ocean University of
Qingdao, 5 Yushan Road, Qingdao 266003, China
email: [email protected]
Recently the subtropical cells (STCs), especially Pacific STCs, have received significantly
attention, because they are considered to play an important role in climate variability. STCs
cycle water subducted in the subtropics to equator, where it up wells and flows back pole
ward at surface, exchanging heat and freshwater with the atmosphere. Apparently STCs act as
a mechanism for transferring mass, heat, salt and tracers between the subtropical and
equatorial gyres. Model results suggest STCs play a potential role in modulating climate
through equatorial SST either by advecting water subducted with anomalous temperature
and/or salinity in the subtropics to the equator where it up wells, or by varying the amount of
subtropical water adverted to the equator which may in turn modulate processes such as
ENSO that control equatorial SST. At present, the “mean” pathways of the Pacific STC are
fairly clear from published observations. There the STCs will be followed in four limbs: (1)
their origin at extra tropical subduction regions, (2) their equator ward progress in the
pycnocline, both at the western boundary and in the interior, (3) their upwelling sites on and
off the equator, and (4) their pole ward return at the surface. But the variability of the Pacific
STC and its relation to ENSO are difficult to study from observations alone. In this project,
we will use NCEP and SODA reanalysis data sets to diagnostic analyze Pacific STCs’
variability and its relation to ENSO.
4. Sea Fog over the Yellow Sea
Dr. Gang Fu, Professor,
Dept. of Marine Meteorology, Ocean University of Qingdao,
Qingdao, Shan dong Province, 266003 China
E-mail: [email protected]
1.Background
Sea fog is one kind of serious weather phenomena that occurred over oceans. As heavy sea
fog usually associates with low visibility, and may cause accidents in the air, land and oceanic
transportations, it has been widely investigated in the coastal nations.
The previous studies have shown that the Yellow Sea (YS) is one of regions where sea fog
occurs frequently (Jing, 1980; Wang, 1983; Zhou and Liu, 1986, Hu and Zhou, 1998: Fu et al.,
2001). Generally, the sea fog off the coast of Qingdao can be classified into three types: (1)
Behind the high-pressure system over sea; (2) in front of the low-pressure system; (3) in front
of high-pressure system. Zhou and Liu (1986) indicated that for the fog over the YS, the
advection fog is dominant. (It is more than 80%), the other is front fog. Although some
preliminary knowledge on the sea fog has been gained, the detailed characteristics of sea fog
over the YS region is not very clear due to the limitation of observation.
2.Study content
(1) General features of sea fog over the YS region.
(2) Structure of sea fog off the coast of Qingdao by analysis of NCEP/AVN data.
(3) Comparison of sea fog over the YS and the other region.
3. References
1. Wang Binhua, 1983: Sea Fog, China Ocean Press, Beijing.
2. Fu Gang, Zhou Faxiu, Zhang Tao, Yuan Zhikang, Li Xunqiang and Jiang Guorong, 2001:
The Characteristics of Sea Fog over the Yellow Sea and the East China Sea, Dynamics of
Atmospheric and Oceanic Circulation and Climate, China Meteorological Press, P447-460.
4.Requirement for student
He or she must have atmospheric science background, as well as the computer plotting
knowledge, especially GRADS (The Grid Analysis and Display System) software (Brian
Doty, 1995).
5. The grazing of mesozooplankton on different phytoplankton
species in the Jiaozhou Bay
Sun Jun, Senior Lecture, Marine Life Science College, Ocean University of Qingdao,
Qingdao, Shan-dong, 266003 P. R. CHINA
E-mail: [email protected]
1. Background
Phytoplankton is the main primary producer and food source of zooplankton in the ocean.
Mesozooplankton mainly ingest micro-phytoplankton which is in the size scale of
20~2000μm. So the study on grazing relationship between phytoplankton and
mesozooplankton is quite important in the coastal seas, like the Jiaozhou Bay, which
characteristic of phytoplankton community dominated by the micro-phytoplankton. Several
methods can determine the grazing of mesozooplankton on phytoplankton, such as gut
pigments, estimated by experimental models and incubation experiment etc. We will
choose the incubation methods as the basic method to determine the grazing of
mesozooplankton in this study. Combined study with one of the other methods, such as gut
pigment or mathematic calculating, will also be considered if the incubation experiment is
successful.
The incubation experiment is described as follows: copepod or dominant
mesozooplankton species was collected from pier waters with hand plankton net, picked up
with pipette and incubated in beaker with single phytoplankton species or filtered sea water
which already got rid of mesozooplankton by 200μm mesh. A control was defined as
without those copepod. After several hours’ incubation, the phytoplankton abundance was
checked under microscope for determining the changes of prey concentration. Ingestion
rate was calculated from cell counts of control beaker and separately for each beaker with
grazers. The growth constant for algal growth, k was calculated from C2  C1e k ( t2 t1 )
where C1 and C2 are cell concentrations (cells/ml) in the control beaker at t1 and t2. For
each beaker with grazer the grazing coefficient, g was calculated from
C2 *  C1 * e ( k  g )( t2 t1 ) where C1* and C2* are cell concentrations (cells/ml) in a beaker with
grazer at time t1 and t2. Using values of k and g, the average cell concentration, <C>, for
C1 * [e ( k  g )( t2 t1 )  1]
each grazer beaker during a time interval t2 - t1 is:  C 
. Although
(t2  t1 )( k  g )
copepod obtains its food by means of filtering maxillae, true filtering rate (volume of water
passing through the maxillary filter per unit time) cannot be directly measured. The volume
swept clear, F is given by F  Vg / N (ml copepod-1 hr-1), where V is the volume (ml) of
the beaker and N is the number of copepods in the beaker. The ingestion rate, I, is then
I  C  F (cells eaten copepod-1 hr-1).
2. Study content
(1) Phytoplankton species isolate
(2) Culture phytoplankton species in lab.
(3) Basic incubation skills
(4) Phytoplankton cell counting
(5) Model calculating skills
(6) Cell concentration of prey on ingestion rate
3. Reference
1. Hallegraeff G M et al. (eds) 1995. Manual on harmful marine micro-algae.
UNESCO Press.
2. Frost B W. 1972. Effects of size and concentration of food particles on the feeding
behavior of the marine planktonic copepod Calanus pacificus. Limnology and
Oceanography, 17:805-815
4. Requirement for student
He or she must have some biological background.
6. The effect of sewage discharge on the growth of algae in
Qingdao
Liu Dongyan, Senior Lecture, Marine Life Science College, Ocean University of Qingdao,
Qingdao, Shandong, 266003 China
E-mail: [email protected]
1.Background
Algae are the main primary producer and food source of benthic animals in the tideland. In
recent years, they are destroyed seriously due to sewage discharge and tourism. The
community of algae changed a lot, such as the declination of abundance, the disappearance
of some species and variation of shape. At last, it will result in the destruction of ecological
balance in tideland. To know the source and component of sewage, the alternative tendency
of algae community and the resistibility of different species to the sewage concentration
become more and more important in order to control the discharge of sewage. We will
carry out this study in Qingdao city where located near to the sea. It is an important travel
city in China and has one million populations. Large domestic and industrial swages
discharge into the sea every year. Our research will provide some suggestion that benefit to
the government management on the environment.
2. Study content
(1) Analysis of algae community
(2) Source and component of sewage
(3) Resistibility of different species to the sewage concentration
3. Reference
1. Traaen, TS Effects of Effluents from a Variety of Sewage Treatment Methods on Primary
Productivity, Respiration and Algal Communities in Artificial Stream Channels,
Verhandlungen Internationale Vereinigung fur Theoretische und ungewardte Limnologie Vol.
20, Part 3, p 1767-1771, 1978. 3 fig, 5 ref.
2. Squires, MM; Lesack, LFW*, Benthic algal response to pulsed versus distributed inputs of
sediments and nutrients in a Mackenzie Delta lake, Journal of the North American
Benthological Society [J. N. Am. Benthol. Soc.], vol. 20, no. 3, pp. 369-384, Sep 2001
3. Havens, KE; Hauxwell, J; Tyler, AC; Thomas, S; McGlathery, KJ; Cebrian, J; Valiela, I;
Steinman, AD; Hwang, S-J. Complex interactions between autotrophs in shallow marine and
freshwater ecosystems: implications for community responses to nutrient stress,
Environmental Pollution [Environ. Pollut.], vol. 113, no. 1, pp. 95-107, 2001
4. Riera, P; Stal, LJ; Nieuwenhuize, J Heavy. Delta N in Intertidal Benthic Algae and
Invertebrates in the Scheldt Estuary (The Netherlands): Effect of River Nitrogen Inputs,
Estuarine, Coastal and Shelf Science [Estuar. Coast. Shelf Sci.], vol. 51, no. 3, pp. 365-372,
Sep 2000
4. Requirement for student
He or she must have some biological background.
7. The inter-decadal variation of Global Evaporation and
Precipitation with Special Emphasis on the Equatorial Pacific
Meng Xiangfeng, Postdoctoral associate, Wu Dexing, Professor,
Institute of Physical Oceanography, Ocean University of Qingdao,
Qingdao, 266003 China
Email: [email protected]
1. Background
Evaporation and Precipitation is an important index for climatologically variation. When
there are anomalous climate events such as EI Nino, Evaporation and Precipitation will
behave abnormally. Evaporation and Precipitation is also one of important driving forces of
ocean and atmosphere circulation. Evaporation and Precipitation can absorb or gives out heat
to the air and change the strength of air motion. So tropical storm is always accompanied by
great rainfall. Evaporation minus Precipitation (E-P) on the ocean is the net fresh water into
the ocean. It can change the strength of thermo cline circulation and cause the climate
variation of decadal background. The most obvious thermo cline circulation mode appears in
Atlantic. Knowledge of Evaporation and Precipitation is important for understanding the
climate variation.
2. Research content
(1) Climatologically spatial structure and characteristics, seasonal variation of E-P in the
globe.
(2) The temporal characteristics of E-P variation
(3) Main period of E-P variation
(4) E-P’s Variation’s in ENSO periods
3. Tools and materials for research
Data: COADS, etc
Mathematics: time series analysis, EOF, wavelets transformation, FFT transformation
4. Requirement for student
Meteorology or oceanography background
Knowledge of time series analysis, MATLAB or other graphical tools
8.The Subsurface Indian Ocean Dipole Mode
Tian Jiwei, Professor, Physical Oceanography department, Ocean University of Qingdao,
Qingdao, Shan-dong, 266003 China
E-mail: [email protected]
1. Background
Indian Ocean dipole mode is the subject of many research reports in recent years. In
1999, Saji et al. first proposed the tropical Indian Ocean dipole. That is cold anomaly
temperature in the eastern coastal of Sumtra and Java, warm anomaly temperature in the
western Indian Ocean in some years. These previous results are mostly obtained by
analyzing the sea surface temperature but a stronger subsurface temperature dipole mode in
the tropical Indian Ocean has not yet been revealed in detail. We will use SODA to analyze
subsurface temperature structure of the tropical Indian Ocean. The main purpose of the
project is to understand the subsurface dipole mode in Indian Ocean.
2. Study content
(1) Data analysis
(2) Study some methods such as EOF, EMD, Wavelet analysis.
3 Reference
1. Webster, P. J., A.M. Moore, J.P. Loschnigg, and R.R. Leben, Coupled ocean-atmosphere
dynamics in the Indian Ocean during 1997-1998. Nature 401, 356-360 (1999).
2.Saji, N. H., B.N. Goswami, P.N. Vinayachandran, and T. Yamagata. A dipole mode in the
tropical Indian Ocean. Nature 401, 360-363 (1999).
4 Requirement for student
He or She must have some physical oceanography background.