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CICS Executive Board, Fellows and External Principal Investigator
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CICS Executive Board Members
Isaac M. Held, GFDL Senior Research Scientist
Hiram Levy II, GFDL Senior Research Scientist
Denise L. Mauzerall, Assistant Professor of Public and International Affairs
Michael Oppenheimer, Professor Geosciences and Public and International Affairs
Stephen W. Pacala, Professor of Ecology and Evolutionary Biology
S. George H. Philander, Director of AOS and Professor of Geosciences
V. Ramaswamy, GFDL Senior Research Scientist
Ignacio Rodriguez-Iturbe, Professor Civil and Environmental Engineering
Jorge L. Sarmiento, Director of CICS and Professor of Geosciences
Geoffrey K. Vallis, Associate Director of CICS and Senior Research Oceanographer
CICS Fellows
Lars O. Hedin, Professor of Ecology and Evolutionary Biology and Princeton Environmental Institute
Sonya A. Legg, Lecturer of Geosciences and Research Oceanographer in the Program of Atmospheric
and Oceanic Sciences
Michael Oppenheimer, Professor in Geosciences and International Affairs, Woodrow Wilson School
Stephen W. Pacala, Professor in Ecology and Evolutionary Biology, Acting Director of Princeton
Environmental Institute
S. George H. Philander, Professor in Geosciences, Director of the Program in Atmospheric and Oceanic
Sciences
Ignacio Rodriguez-Iturbe, Professor in Environmental Sciences, Professor of Civil and Environmental
Engineering
Jorge L. Sarmiento, Professor of Geosciences, Director of CICS
Daniel M. Sigman, Assistant Professor of Geosciences
Eric F. Wood, Professor of Civil and Environmental Engineering
External Principal Investigators
Dale B. Haidvogel, Professor at Rutgers University
Thomas W. N. Haine, Professor at Johns Hopkins University
George C. Hurtt, Professor at the University of New Hampshire
Eli Tziperman, Professor at Harvard University
Charles J. Vörösmarty, Professor at the University of New Hampshire
Dale B. Haidvogel
Dr. Dale B. Haidvogel is a Professor of Marine Sciences at the Institute of Marine
and Coastal Sciences of Rutgers University, New Brunswick, New Jersey. After
completing his doctoral studies at the Massachusetts Institute of Technology and
the Woods Hole Oceanographic Institution (MIT-WHOI Joint Program) in 1976,
he pursued postdoctoral studies in the Center for Earth and Planetary Physics of
Harvard University. Since that time, he has held professional appointments at
WHOI (1978-1982), the National Center for Atmospheric Research (1982-1986),
the Johns Hopkins University (1986-1990), and finally Rutgers University (1990present).
Dr. Haidvogel's primary research interests include the development of advanced algorithms for
geophysical modeling (e.g., high-order finite element and finite volume methods; see Choi et al., 2004,
Mon. Wea. Rev., 132, 1777--1791), the coupled modeling of regional climate impacts (e.g., the
ecosystems of the Northeast Pacific; Hermann et al., 2002. Prog. Oceanogr., 53, 335--367), numerical
and laboratory studies of fundamental processes (e.g., flow-topography interaction; see Curchitser et al.,
2001. J. Phys. Oceanogr., 31, 725--745 and Boyer et al., 2004, J. Phys. Oceanogr., 34, 1588--1609),
ocean observing systems and data assimilation (e.g., in the Northwest Atlantic; see
http://marine.rutgers.edu/mrs/), quantitative metrics for ocean model performance (see
http://marine.rutgers.edu/po/index.php), and the promotion and distribution of ocean modeling systems
and products (http://www.ocean-modeling.org/).
Dr. Haidvogel has participated in the scientific planning and/or execution of many large-scale, multiinstitutional and international oceanographic programs of the last three decades, including the Mid-Ocean
Dynamics Experiment (MODE, PolyMODE), the World Ocean Circulation Experiment (WOCE), and
most recently the Global Ocean Ecosystems Dynamics project (GLOBEC). He has served on the
Scientific Steering Committees for U.S. WOCE and U.S. GLOBEC, and is currently Chair of the U.S.
GLOBEC SSC. He was Co-Editor of the journal Dynamics of Atmospheres and Oceans from 1980 until
2005.
Dr. Haidvogel founded and directs the IMCS Rutgers’ Ocean Modeling Group, which has as one of it
foremost goals the development, verification and interdisciplinary application of new regional and basinscale ocean modeling systems, including coupled models for (e.g.) atmosphere/ocean, biogeochemical,
and/or ecosystem response. Modeling software developed by the Ocean Modeling Group, and its
colleagues, has been distributed worldwide to approximately 1000 scientists.
Thomas W. N. Haine
Dr. Thomas W. N. Haine is an Associate Professor in the Department of Earth & Planetary Sciences at
Johns Hopkins University in Baltimore, MD.
Research Interests & Accomplishments:
My research is in the physics of the basin-scale ocean and its role in Earth's
climate. I am involved in improving estimates of the geophysical state of
the ocean circulation through analysis of field data and circulation model
results. The subpolar North Atlantic ventilation process (rates, pathways,
variability, and mechanisms) interests me in particular. I also investigate
key physical processes that maintain the state of the extra-tropical
upper ocean focusing on fluid dynamics and thermodynamics and
their role in controlling sea surface temperature variability over years
to decades. In particular, my current research projects are to:
•
Identify and understand the tracer-independent transport
information contained in ocean tracer data.
•
Identify and understand the dynamic and thermodynamic mechanisms controlling midlatitude
interannual SST variability.
•
Improve understanding of the circulation and dynamics of the Denmark Strait, East Greenland
Shelf, and Irminger Sea.
•
Understand the dynamics of rotating stratified fluids in laboratory experiments involving nonlinear interactions.
These projects are currently sponsored by the National Science Foundation, National Aeronautics and
Space Administration, Johns Hopkins University, and the National Oceanic & Atmospheric Agency.
In the last three years I have advised 8 graduate students and 3 post docs. I have received many invitations
to speak in seminar series, at workshops, and in short courses. I have published about 20 articles in the
scientific literature during this time. I was also an invited participant at the National Academy of
Sciences, US Frontiers of Science Symposium, an Invited Visiting Professor at Catholique Universite de
Louvain-la-Neuve, Belgium, and am listed in Who's Who in the World, Who's Who in America, and 2000
Outstanding Intellectuals of the 21st Century.
Lars O. Hedin
Dr. Lars O. Hedin is a Professor in the Department of Ecology and Evolutionary Biology and the
Princeton Environmental Institute at Princeton University,NJ. He has held
faculty positions at Cornell University and Michigan State University.
Dr. Hedin's research focuses onunderstanding natural ecosystems as complex
biogeochemical systems, with emphasis on evolutionary implications for
plant and microbial communities. He has received the Mercer Award from
the Ecological Society of America for his work on developing "baseline"
understanding nutrient cycles in pristine South American forests, against
which mechanisms and extents of human impacts can be interpreted. He
has for over a decade studied remote forests in southern Chile and Argentina,
and, more recently, tropical forests in the Hawaiian archipelago, the Amazon,
Central America, as well as forests in New Zealand. Dr. Hedin recently
chaired a white paper report on "Challenges to Linking Ecological Biology
and Geosciences" to the National Science Foundation (NSF), and is one of the founders of the
biogeosciences section of the Ecological Society of America. He has published over 40 peer-reviewed
articles in journals including Nature, PNAS, Scientific American, Ecology, and Global Biogeochemical
Cycles, and his findings have been broadly covered in the scientific and public media.
Isaac M. Held
Dr. Isaac Held is a Senior Research Scientist at NOAA's
Geophysical Fluid Dynamics Laboratory, where he conducts
research on climate dynamics and climate modeling, and is
head of the Weather and Atmospheric Dynamics Group.
After receiving his Ph.D. at Princeton University, and after
a short stint at Harvard University, he joined GFDL in 1978
and has remained there ever since. He is also a lecturer with
rank of Professor at Princeton University, in its Atmospheric
and Oceanic Sciences Program, where he has supervised
over a dozen Ph.D. theses. He also serves as an Associate
Faculty member in Princeton's Applied and Computational
Mathematics Program and in the Princeton Environmental
Institute. Dr. Held is a Fellow of the American Meteorological Society (1991) and the American
Geophysical Union (1995), and a member of the National Academy of Sciences (2003). He has received
the Meisinger Award of the AMS (1987) for "outstanding contributions to the study of climate dynamics
....", the Bernhard Haurwitz Memorial Lectureship of the AMS (1999), the Rosenstiel Award from the
University of Miami (1994) "for breadth and incisiveness is attacking fundamental problems of
geophysical fluid dynamics, the general circulation of the atmosphere, and climate dynamics", the
Department of Commerce Gold Medal (1999) "for world leadership in studies of climate dynamics", the
NOAA Presidential Rank Award (2005).
George C. Hurtt
Dr. George Hurtt is an Assistant Professor in Community and Ecosystem
Ecology at the University of New Hampshire. He earned a B.A. in Biology
from Middlebury College in 1990. His advanced degrees are in Ecology and
Evolutionary Biology. In 1992 he received a M.S. from the University of
Connecticut. In 1994 he received a M.A., and in 1997 a Ph.D., from
Princeton University. He was a Postdoctoral Fellow at Princeton prior to
joining the faculty at the University of New Hampshire in 1998.
Dr. Hurtt is interested in the theory and application of community and
ecosystem ecology. His primary approach is to combine mathematics and
data to develop models for understanding and predicting the structure and
dynamics of ecological systems. He has published on a wide range of topics
including: the role of dispersal in the dynamics and structure of plant communities, latitudinal and
elevational gradients in biodiversity, and ocean and terrestrial ecosystem models for use in studies of the
global carbon cycle and global climate change.
Current research is focused on the development and application of a new terrestrial ecosystem model that
essentially takes a "statistical mechanics" approach to scaling local dynamics to global scales. This model
is being used to address issues such as: the sustainability of land-use practices, the potential for terrestrial
ecosystems as a carbon sink, and the response and feedback of terrestrial ecosystems to climate and
climate change. Dr. Hurtt is involved in several collaborative research projects including the Large Scale
Biosphere-Atmosphere Experiment in South America, an Interdisciplinary Science Investigation using
NASA's Earth Observing System, and efforts to develop global carbon system and land surface models.
He is a coauthor and scientific spokesperson for the New England Regional Assessment of the Potential
Consequences of Climate Variability and Change, and has testified to both the New Hampshire
Legislature and U.S. Congress on the science of global change.
Sonya Legg
Sonya Legg received her PhD from Imperial College, London in 1993, and
carried out postdoctoral research at the University of Colorado, Boulder, and at
UCLA, the latter as a NOAA Climate and Global Change postdoctoral fellow.
Prior to arrival in Princeton in September 2004, she worked for seven years as a
scientist in the physical oceanography department of the Woods Hole
Oceanographic Institution, where she was recently awarded tenure. During her
time at WHOI Legg was involved in the MIT-WHOI graduate program, serving
on the Joint Committee for Physical Oceanography, and teaching a graduate
course in turbulence. Legg is currently an associate member of the
IAPSO/SCOR working group 121 on Ocean Mixing, and a member of the US
CLIVAR Process Studies and Model Improvement Panel. Legg’s research interests focus on turbulent
mixing in the ocean, with primary tools being numerical simulation and theory. Particular processes of
current interest include tidal mixing and mixing in overflows. A new emphasis since coming to Princeton
is the representation of mixing processes in large scale ocean models such as the GFDL MOM.
During the past year Legg has carried out a numerical study of the generation of internal waves and
mixing by tidal flow over isolated ridges, such as the Hawaiian Ridge. Of particular interest are the
relative proportions of energy entering the wave field and dissipated locally. This study has shown that
this ratio depends strongly on the horizontal scale of the topography, with dissipation being most effective
for very narrow topography. This work was presented at the Ocean Mixing Symposium in Victoria,
Canada, in October 2004, and has been accepted for publication in a special volume of Deep Sea
Research. Next Legg intends to incorporate these results into new models of tidal mixing for inclusion in
ocean general circulation models.
A second major activity of the past year has been the study of overflow mixing processes. Legg is the
coordinating PI for a multi-institutional collaboration, the Gravity Current Entrainment Climate Process
Team. This CPT brings together observationalists, theoreticians and those carrying out numerical process
studies with developers of large scale ocean models such as the GFDL MOM. In addition to being
responsible for the organization of the annual workshop in Providence in November 2004, the
development and maintenance of the webpage http://www.cpt-gce.org/ , the supervision of a postdoc,
Ulrike Riemenschneider, based in Woods Hole, and the preparation of annual reports and numerous
presentations, Legg has been active in carrying out several research components of this project. These
include a comparison of z-coordinate and isopycnal coordinate representations of overflows with Robert
Hallberg (now published in Ocean Modelling) and development of a parameterization of shear-driven
mixing in a stratified flow (with Robert Hallberg and Laura Jackson).
Hiram Levy, II
Dr. Hiram Levy is a Senior Research Scientist and Lecturer in
the Department of Geosciences and the Program in Atmospheric
and Oceanic Sciences, Princeton University. His current research
examines the impact of human activity on the chemistry of the
atmosphere and its resulting impact on global air quality, climate,
and global biogeochemical cycles. Some specific topics are: The
influence of aerosols, both natural and anthropogenic, on air
quality and climate; The impact of changing biogenic hydrocarbon emissions on air quality; The interannual variability in
CO2 sinks, sources and accumulation; The impact of human
fixation of nitrogen on global nitrogen biogeochemistry.
Current Research Programs and Collaborations include the
following:
1. Biospheric Processes Group [GFDL] - Will work to understand the interactions between the
earth's biosphere and climate and assess the impact of human activities.
2. China-MAP [NASA] A measurement and modeling program dedicated to studying the local,
regional, and hemispheric impact of pollution emitted from China on both climate and
atmospheric chemistry.
3. ITCT [NOAA] and ITCT [Center for Global and Regional Environmental
Research/University of Iowa] - A coordinated international research program to investigate
intercontinental transport of manmade pollution, with an emphasis on ozone, fine particles,
and other chemically active "greenhouse" compounds.
Courses taught at Princeton University include: Chemistry of the Environment - CHM333/GEO333;
Atmospheric Chemistry and Transport and Atmospheric Chemistry
Publications:
Fan, S-M., L. W. Horowitz, H. Levy II, and W. J. Moxim, 2004: Impact of air pollution on wet
deposition of mineral dust aerosols. Geophysical Research Letters, 31, L02104,
doi:10.1029/2003GL018501.
Phadnis, M. J., H. Levy II, and W. J. Moxim, 2002: On the evolution of pollution from South and
Southeast Asia during the winter-spring monsoon. Journal of Geophysical Research, 107(D24), 4790,
doi:10.1029/2002JD002190.
Yienger, J. J., M. Galanter, T. A. Holloway, M. J. Phadnis, S. K. Guttikunda, G. R. Carmichael, W.
J. Moxim, and H. Levy II, 2000: The episodic nature of air pollution transport from Asia to North
America. Journal of Geophysical Research, 105(D22), 26,931-26,945.
Denise L. Mauzerall
Dr. Denise L. Mauzerall is an Assistant Professor of Public and
International Affairs at Princeton University’s Woodrow Wilson School.
She completed her undergraduate degree in Chemistry in 1985 at Brown
University, a Master’s Degree in Environmental Engineering at Stanford
University in 1988, and her Ph.D. in Atmospheric Chemistry at Harvard
University in 1996. Previously she was a program manager in the
Global Change Division of the U.S. Environmental Protection Agency
and a post-doctoral fellow at the National Center for Atmospheric
Research.
Research in Dr. Mauzerall’s group uses science to contribute to the
formation of far-sighted environmental policy. Her research addresses the following central questions:
1) What are present and potential future regional and global levels of air pollution?
2) What are/will be the impacts of air pollution to human health and welfare including climate change?
3) What are appropriate energy and air pollution policy responses?
She seeks to answer these questions through research projects on both national and global scales. To
address the first question, she uses computer models of regional and global atmospheric chemistry,
transport and radiation to simulate the emissions of air pollutants, their chemical transformation and
movement around the world. She addresses the second question using tools drawn from agronomy,
epidemiology, engineering and economics. Answers to the first two questions facilitate identification of
appropriate energy and air pollution policy responses.
Her research analyzes the impacts of air pollution in both the largest rapidly industrializing country
(China) and in the largest developed country (US). On a global scale she investigates the intercontinental transport of air pollutants with an emphasis on transport from Asia to the US, and the effect of
emissions of certain air pollutants (ozone precursors and aerosols) on public health and climate change.
Current research includes projects on the impacts of air pollution on agriculture and health in China, intercontinental transport of air pollutants, environmental consequences and alternatives to nitrogen oxide
emissions trading, regional attribution of ozone production and associated radiative forcing to emissions
from specific regions of the world, and the effect that methane emission controls can have on reducing
background ozone concentrations and the associated benefits for human health and climate change.
These issues are interlinked, globally pervasive and addressing one provides opportunities for leveraging
solutions to others. Identifying policies which can simultaneously reduce the emission of reactive air
pollutants and of greenhouse gases are particularly desirable.
Michael Oppenheimer
Dr. Michael Oppenheimer is the Albert G. Milbank Professor of
Geosciences and International Affairs at Princeton University. He is
also the Director of the Program in Science, Technology and
Environmental Policy (STEP) at the Woodrow Wilson School, and
Associated Faculty of the Princeton Environmental Institute and the
Atmosphere and Ocean Sciences Program. He joined the Princeton
faculty after more than two decades with Environmental Defense. His
interests include science and policy of the atmosphere, particularly
climate change and its impacts. His research explores the potential
effects of global warming, including the effects of warming on
ecosystems and on the nitrogen cycle; and on the ice sheets in the
context of defining “dangerous anthropogenic interference” with the
climate system. He served as a lead author of the Third Assessment
Report of the Intergovernmental Panel on Climate Change, and is also a
lead author for the Fourth Assessment. He was a member of the
National Research Council's Panel on the Atmospheric Effects of
Aviation, and currently is a member of the NRC’s panel on "Earth Science and Applications from Space:
A Community Assessment and Strategy for the Future". He also has served on several university and
institutional advisory boards. Prior to his position at Environmental Defense, Dr. Oppenheimer served as
Atomic and Molecular Astrophysicist at the Harvard-Smithsonian Center for Astrophysics and Lecturer
on Astronomy at Harvard University. He received an S.B. in chemistry from M.I.T., a Ph.D. in chemical
physics from the University of Chicago, and pursued post-doctoral research at the Harvard-Smithsonian
Center for Astrophysics.
Stephen W. Pacala
Dr. Stephen W. Pacala is the Frederick D. Petrie Professor of Ecology and Evolutionary Biology at
Princeton University. He completed an undergraduate degree in biology at Dartmouth College in 1978
and a Ph.D. in ecology at Stanford University in 1982. He was
Assistant and Associate Professor at the University of Connecticut
from 1982 to 1992, and then moved to Princeton University as
Professor of Ecology in 1992. He was awarded the Frederick D.
Petrie Chair in 2000. He has served on numerous editorial and
advisory boards.
Dr. Pacala has researched problems in a wide variety of ecological
and mathematical topics. These include the maintenance of biodiversity, the mathematics of scaling, ecosystem modeling,
ecological statistics, the dynamics of vegetation, animal behavior,
the stability of host-parasitoid interactions, the relationship between
biodiversity on ecosystem function, and field studies of plants, lizards, birds, fish, insects, and parasites.
Since moving to Princeton University, Dr. Pacala has focused on problems of global change with an
emphasis on the biological regulation of greenhouse gases and climate. He currently co-directs the
Princeton Carbon Mitigation Initiative and directs the Princeton Environmental Institute.
S. George H. Philander
Dr. George Philander is the Knox Taylor Professor of Geosciences and the Director, Atmospheric and
Oceanic Sciences Program at Princeton University. He obtained his Ph.D. at Harvard University in 1970.
He studies interactions between the ocean and atmosphere and their role
in climate fluctuations and climate changes, in the past and the present.
He is particularly interested in El Niño, a phenomenon that brings droughts
to the western tropical Pacific, torrential rains to the eastern tropical
Pacific, and unusual weather patterns to much of the globe. From an
atmospheric point of view, El Niño is attributable to changes in the
temperature of the surface waters of the eastern tropical Pacific Ocean
sea surface, changes that in turn are caused by altered atmospheric
conditions. The ocean-atmosphere interactions implied by this circular
argument can also affect global climate changes such as the recurrent ice
ages. This possibility is currently being explored by means of a hierarchy
of coupled ocean-atmosphere models, from relatively simple analytical
models to complex General Circulation Models that require a supercomputer. Philander is a fellow of the National Academy of Sciences,
the American Geophysical Union, and the American Meteorological
Society.
V. Ramaswamy
Dr. Ramaswamy is a Senior Scientist at NOAA’s Geosphysical Fluid Dynamic Laboratory. His
principal focus of research is the investigation of the climatic effects due to radiatively active gases,
aerosols and clouds in the atmosphere. Radiative transfer models of high precision have been developed
to determine the forcing exerted by different species upon the
surface-atmosphere system. Currently, the perturbations due to
changing concentrations of greenhouse gases and aerosols
since pre-industrial times are being examined. Numerical
models of the atmosphere are used to study the transport and
transformation of the species, and to assess their climatic
impacts. Another major research aim is to understand the
hydrologic cycle in the atmosphere, in particular the processes
governing the distribution of water vapor, and the formation,
maintenance and dissipation of clouds. The physical properties
of aerosols and clouds play a significant role in the radiative
balance of the planet, and their accurate evaluation is essential
for resolving issues concerning global change. Mathematical models of varying complexity are employed
to study different aspects of the global cloud-climate interactions problem. This effort is aided by
diagnostic analyses of data drawn from a variety of meteorological and satellite observations.
Publications:
Erlick, C., and V. Ramaswamy, Note on the definition of clear sky in calculations of shortwave cloud
forcing, Journal of Geophysical Research, 108, D5, 4156, doi: 10.1029/2002JD002990, 2003.
Garrett, T. J., Lynn Russell, V. Ramaswamy, S. F. Maria, and B. H. Huebert, Microphysical and
radiative Evolution of Aerosol Plumes Over the tropical North Atlantic Ocean, Journal of Geophysical
Research, 108,4022,DOI: 10.1029/2002JD002228, 2003.
Randles, C. A., L. M. Russell, and V. Ramaswamy, Hygroscopic and optical properties of organic sea
salt aerosol and consequences for climate forcing, Geophysical Research Letters, 31(L16108),
doi:10.1029/2004GL020628, 2004.
Ignacio Rodriguez-Iturbe
Dr. Ignacio Rodriguez-Iturbe is the Theodora Shelton Pitney Professor in Environmental Sciences and
Professor of Civil and Environmental Engineering at Princeton University. He obtained his Ph.D. at
Colorado State University in 1967. The dynamics of the interaction between climate, soil, and vegetation
are the main focus of Rodriguez-Iturbe’s research group. These
dynamics are crucially influenced by the scale at which the
phenomena are studied as well as by the type of climate, the
physiological characteristics of the vegetation, and the edology
of the soil. Moreover, not only the temporal aspects but also
the spatial aspects of the dynamics are crucially dependent on
the above factors. Soil moisture plays a key role in these
dynamics, and his group is involved in its space-time
characterization. This involves a range of approaches that
include challenging problems in the physics of the interaction
as well as on its mathematical description. It is necessary to
account for the random character of precipitation, both in
occurrence and intensity, as well as for the nonlinear dependence of infiltration, evapotranspiration, and
leakage on the soil moisture state. His group’s approach has been to understand and model first the
balance of soil moisture at a point under the above conditions. The solution of the stochastic differential
equations corresponding to the point dynamics has provided the probabilistic description of the soil-plantclimate interaction at a site. The spatial interaction between different sites with the same or with different
types of vegetation is being implemented via cellular automatas operating under rules governed by the
characteristics of the stress existing in the vegetation. At larger spatial scales, precipitation itself is
influenced by the soil moisture present in the region, and this phenomenon needs to be incorporated into
the modeling scheme. At intermediate scales involving river basins, the geomorphologic characteristics of
the drainage network is a commanding factor in the spatial organization of soil moisture. Rodriguez
Iturbe’s group is trying to link the recent advances on the scaling characteristics of the network with the
dynamics of the soil moisture. With the above framework the group hopes to elucidate some of the most
fundamental issues of the climate-soil-atmosphere interaction that lie at the heart of hydrology.
Rodriguez-Iturbe was awarded the Stockholm Water Prize in 2002.
Jorge L. Sarmiento
Dr. Jorge L. Sarmiento is a Professor of Geosciences at Princeton University. He obtained his Ph.D. at
the Lamont-Doherty Geological Observatory of Columbia University in 1978, and then served as a postdoc at the Geophysical Fluid Dynamics Laboratory/NOAA in Princeton
before joining the Princeton University faculty in 1980. He has published
widely on the oceanic cycles of climatically important chemicals such as
carbon dioxide, on the use of chemical tracers to study ocean circulation,
and on the impact of climate change on ocean biogeochemistry. He has
participated in the scientific planning and execution of many of the largescale multi-institutional and international oceanographic biogeochemical
and tracer programs of the last two decades. He was Director of Princeton's
Atmospheric and Oceanic Sciences Program from 1980 to 1990, and is
presently Director of the newly formed Cooperative Institute for Climate
Science. He has served on the editorial board of multiple journals and as
editor of Global Biogeochemical Cycles. He is a Fellow of the American
Geophysical Union and the American Association for the Advancement of
Science.
Daniel M. Sigman
Dr. Daniel M. Sigman is an Assistant Professor of Geosciences at Princeton
University. He obtained his Ph.D. at Massachusetts Institute of Technology and
Woods Hole Oceanographic Institution in 1997. He studies the cycles of
biologically important elements and their interaction with changing environmental
conditions through the course of Earth history. His current research activities
include the development of stable isotope methods by which to track the marine
nitrogen cycle, today and in the past, and the construction of simple geochemical
models for paleoceanographic and Earth history studies. Much of his work to date
has focused on the oscillation between ice ages and interglacial periods that has dominated Earth’s
climate for the last two million years. These cyclic climatic changes provide an important test case for the
interaction between physical and biological processes in setting environmental conditions on Earth.
Ongoing studies of the nitrogen cycle in the modern ocean use the isotopic composition of dissolved
nitrogen species to understand the internal cycles and input/output budgets of nitrogen and other
biologically important elements in the ocean. Sigman’s studies of the history of the nitrogen cycle make
use of the organic matter preserved within microfossils as a recorder of nutrient dynamics in the surface
ocean, with the goal of understanding the relationship between nutrient supply and algal growth, which
may be an important driver of past changes in the atmospheric concentration of carbon dioxide. Through
the work of his students and collaborators at Princeton, Sigman has also begun to explore the atmospheric
reactive nitrogen cycle and the nitrogen budgets of terrestrial ecosystems, both their modern conditions
and their changes through time.
Eli Tziperman
Dr. Eli Tziperman obtained a B.A. in Physics and Mathematics from Hebrew University in Jerusalem
(1982), Ph.D. in Physical Oceanography from the joint program in
Oceanography of MIT and WHOI (1987). He was at the Weizmann
Institute of Science until 2003, and has been in the Department of Earth
and Planetary Sciences and the Division of Engineering and Applied
Sciences at Harvard University since. Over the past 15 years, he spent
two full-year sabbaticals and some 12 two-month summers at GFDL/
Princeton University. His interests include large scale ocean and climate
dynamics, from El Nino’s dynamics, to that of the thermohaline circulation,
Heinrich events and glacial cycles. In addition, a more applied side to his
work involves the development of four dimensional data assimilation
methods based on the adjoint method, in order to try and improve the
prediction skill of El Nino/ La Nina events.
The support from GFDL/Princeton/ Cooperative Institute for Climate
Science (CICS) allowed making significant progress toward completing an adjoint to the latest GFDL
ocean model. This adjoint will be used for sensitivity studies, data assimilation, and ENSO prediction.
The post doc working on this project, Geoffrey Gebbie, has previously completed his PhD at MIT.
Geoffrey Vallis
Dr. Geoffrey Vallis has been at Princeton since 1998. Prior to that,
he was a Professor at the University of California. He works in a
variety of topics in large-scale dynamics in the ocean and
atmosphere. Recent research topics include:
Investigations of the dynamics of the North Atlantic Oscillation and
so-called annular modes of variability. Vallis, in collaboration with
colleagues and students, has shown how the NAO and annular modes
are two sides of the same coin, and how variations in the Atlantic
storm track are intimately tied to the NAO.
Investigations of mesoscale eddy effects in the ocean. With a
Princeton graduate student, Vallis has shown how and why the
mesoscale eddies have a leading order affect on the Antarctic Circumpolar Current.
Investigations of the nature of climate variability on millennial timescales. In collaboration with a
graduate student, Vallis has suggested that a natural instability of the overturning circulation of the ocean
might give rise to Dansgaard-Oeschger oscillations, and explain the nature of climate variability in glacial
climates.
From 1998-2004 he was editor of Journal of Atmospheric Sciences.
He has recently completed a book, Atmospheric and Oceanic Fluid Dynamics, to be published by
Cambridge University Press.
Charles J. Vörösmarty
Dr. Charles J. Vörösmarty is a Research Professor in Biogeochemical
Modeling at the University of New Hampshire. His research interests are
focused on the interaction between hydrology, water resources, and
biogeochemistry, and he has been active in the field for nearly twenty years.
His research has included studies at local, regional, and global scales,
including development of nutrient cycling models in New England coastal
ecosystems; continental to global-scale modeling of water balance, discharge,
sediment and nutrient delivery in the world's large river systems; and the
influences of large-scale water engineering on continental runoff. Dr.
Vörösmarty 's publications have appeared in Science, AMBIO, Climatic
Change, Ecological Applications, Estuaries, Global Biogeochemical Cycles,
Nature, Studies in Geophysics, Journal of Hydrology, and Water Resources
Research.
His research has relied on geographically-specific data sets and models. He and his co-workers have
developed the Global Hydrological Archive and Analysis System (GHAAS), an interactive data base and
scientific visualization package used in analyzing water and biogeochemical cycles at a variety of spatial
scales. Applications of the GHAAS have included: orbital analysis of alternative remote sensing systems
for inland water monitoring, indicators of water resource scarcity, the linking of remote sensing, groundbased meteorological data, and drainage basin models to monitor river discharge; geographically-specific
analysis of the impact of large reservoirs on drainage basin response; development of high resolution
runoff fields from the blending of modelled discharge, observed station data and river networks at the
global scale.
Dr. Vörösmarty has been active in numerous international committees including the International
Geosphere-Biosphere Programme (IGBP) Biospheric Aspects of the Hydrological Cycle and UNESCO's
International Hydrological Programme. He serves as co-chair of ESSP Global Water System Project.
Vörösmarty is a Coordinating Level Author on the freshwater chapter of the Millennium Assessment. He
also serves as President of the International Committee on Atmosphere-Soil-Vegetation Relations of the
International Association of Hydrological Sciences. Main support for his work has come from NASA, the
U.S. Environmental Protection Agency, the Department of Energy, and the National Science Foundation.
Eric F. Wood
Dr. Eric F. Wood is Professor of Civil and Environmental
Engineering at Princeton University and an associated faculty member
in the Geosciences Department and the Princeton Environmental
Institute. After receiving his doctoral degree in Civil Engineering from
the Massachusetts Institute of Technology in 1974, he spent 2 ½ years
at the International Institute of Applied System Analysis in Laxenburg
Austria conducting research into water resources and statistical
hydrology. He joined Princeton University as an Assistant Professor in
the fall of 1976. He has held a number of administrative positions
while at Princeton including acting departmental chair in 1986-1987,
Director of the interdepartmental Program in Environmental
Engineering and Water Resources from 1980 to 1994, and
departmental Director of Graduate Studies from 1994 to 1997 and
currently since July 2005. He has also sat on a number of university committees, including two terms on
the Priority Committee. Dr. Wood is a Fellow of the American Geophysical Union (AGU) and of the
American Meteorological Society. He has received the AGU's Robert E. Horton Award, AMS's Robert E.
Horton Memorial Lectureship and Princeton's Rheinstein Award.
His current research areas include hydroclimatology with an emphasis on land-atmospheric interaction
and the development and validation of large scale terrestrial hydrologic models; hydrological remote
sensing, including the retrievals of soil moisture and evaporation using NASA Earth Observation
satellites; the modeling and analysis of the terrestrial water and energy budgets over a range of scales,
including seasonal climate forecasting and hydrologic prediction studies; and hydrologic impact of
climate change. In the area of remote sensing, he is a Science Team member on the NASA Aqua/Terra
AMSR-E and MODIS instruments, and on the proposed HYDROS soil moisture/freeze-thaw mission. He
also serves on a bilateral NASA/NASDA science steering group for the Global Precipitation Mission
(GPM). As part of his remote sensing science research, he and his research team has helped plan and have
participated in numerous field campaigns over the last 20 years, including Italy, Arizona, Oklahoma and
Iowa. Also, he is developing forward radiative transfer models of terrestrial surface emission for the
NOAA Joint Center for Satellite Data Assimilation. In the area of hydrological modeling, he and
colleagues at the University of Washington have over the last decade developed one of the most widely
used and cited macro-scale land surface models appropriate for climate modeling and global-scale offline simulations. The model also forms the core of the NOAAsupported seasonal hydrologic forecast
system that ingests NCEP seasonal climate predictions and produces seasonal hydrologic predictions, and
a U.S. drought nowcast useful to the NOAA Climate Prediction Center’s drought assessment activities.
Professor Wood has performed extensive professional service to his community, including being a
Council member of the American Meteorological Society (1999-2002), where he currently serves on
their Atmospheric Awards Committee (2003-2005). For the American Geophysical Union, he has
served on numerous committees, including as a member and chair of the Union Fellows Committee and
on the executive of the Hydrology Section. For the World Climate Research Programme, he served on the
Task Force that just completed the strategic plan for the new Coordinated Observations and Predictions of
the Earth System (COPES) and is co-chair of the Science Advisory Group for the U.S. GEWEX Americas
Prediction Project (GAPP). For the National Research Council he has served on the Water Science and
Technology Board (1997-2000) and the Board on Atmospheric Science and Climate (1999-2002), as well
as numerous study and standing committees. Currently he is a member of the joint WSTB/BASC standing
Committee on Hydrological Sciences, where he serves as its Chair, and is vice-chair of the current study
Committee on Integrated Observations for Hydrologic and Related Sciences.
Research Staff, Scholars, Professional Technical Staff
and Postdoctoral Fellow Bios
Alistair Adcroft, Research Oceanographer
Alistair Adcroft received his PhD from Imperial College, London in
1995, and carried out postdoctoral research at the University of
California, Los Angeles, as a UCAR Ocean Modeling postdoctoral
fellow and then at MIT, Cambridge, in the Program in Atmospheres,
Oceans and Climate. He worked at MIT for seven years, first as a
research fellow, then as a research scientist and finally as a principle
research scientist, during which he led the development of the MIT
general circulation model. During this time, he was involved in various
working groups such as the U.S. Climate modeling infrastructure, that
led to the creation of the ESMF project; and the ONR Terrain-coordinate Ocean Modeling Systems
“Expert group”. He has also organized workshops and sessions including the “Z-coordinate ocean
modeling meeting” and the “Future directions” session for CLIVAR ocean modeling workshop. Adcroft
was appointed as a research oceanographer at Princeton University in September, 2004. Adcroft’s
research interests focus on the improvement of models both for climate research and for process studies.
A particular underlying theme involves building robust tools that can seamlessly simulate the wide range
of scales seen in the ocean.
During the past year Adcroft has been working on the foundations of a new kind of ocean model. The
foundations include improved infrastructure capabilities (such as novel grids, nesting, object oriented
components). More recently, he has begun work on the building blocks for the new ocean model, known
as kernels, which embody the shared part of several different ocean models. The kernels will be usable by
existing models and will be the principal components of a new model developed with hybrid vertical
coordinates in mind. The objective is to both unify our current capabilities into one modeling framework
and at the same time to extend our capabilities into a promising research area. The kernels and overall
strategy are being described by white papers which will be sent out to the community for comment: the
expectation being that certain members of the community will want to buy-in to the new software as it
becomes available.
Adcroft has also been working on fine tuning a high-resolution regional model of the Irminger Sea (in
collaboration with Tom Haine, Johns Hopkins Univ.); improving the representation of grid-scale
topography (thin-walls and porous barriers); developing a framework for sub-grid scale eddy closures
which provides the eddy velocity scale to the parameterizations and at the same time makes the model
energetically closed; developing time-stepping methods for the primitive equations that reduces the size
of the state vector; developing vorticity advection schemes that avoid the need for artificially large
viscosities in ocean models.
Andrew S. Altevogt, Research Staff
Department of Civil and Environmental Engineering
Princeton University
Andrew Altevogt received his Ph.D. in Hydrologic Sciences from the
University of California, Davis in 2001. His dissertation was entitled A
Determination of the Flux of Gas Phase Volatile Organic Compounds Due to
Naturally Occurring Environmentally Significant Driving Forces. His research
interests include: Fate and transport of chemicals in porous media,
environmental fluid mechanics, and scale dependent processes. Recent research projects include modeling
the biogeochemical effects of CO2 leakage from areas of geological sequestration and mathematical and
experimental determination of the theoretical relationships between transport and chemical reaction in
porous media.
Currently he is implementing a coupled multi-phase reactive transport model which will describe the
emission of nitrogen compounds during periods of changing soil moisture. The information gained from
this modeling effort will be utilized to examine the temporal and spatial scale dependencies of nitrogen
transformation in soils as zones of anoxia form and then disappear as a result of soil wetting and drying.
Capturing the details of these dynamic processes will enhance the predictive capabilities of future
regional and global scale modeling efforts.
Selected Publications:
Altevogt, A. S. and P. R. Jaffe. “ Biogeochemical Response of Unsaturated Soils to CO2 Intrusion.”
Water Resources Research.. 41:9, W09427. (2005)
Altevogt, A. S. and M. A. Celia. “Numerical Modeling of Carbon Dioxide in Unsaturated Soils due to
Deep Subsurface Leakage”. Water Resources Research. 40:W03509. doi:10.1029/2003WR002848
(2004).
Altevogt, A. S., D. E. Rolston and S. Whitaker. “New Equations for Binary Gas Transport in Porous
Media, Part 1: Equation Development”. Advances in Water Resources. 26:7. pp 695-715. (2003)
Altevogt, A. S., D. E. Rolston and S. Whitaker. “New Equations for Binary Gas Transport in Porous
Media, Part 2: Experimental Validation”. Advances in Water Resources. 26:7. pp 717-723. (2003)
Venkatramani Balaji, Prof. Technical Staff
V. Balaji serves as Head, Modeling Systems Group at the
Cooperative Institute of Climate Sciences of Princeton University.
Balaji’s background is in the modeling of cloudscale dynamics (nonhydrostatic moist convection and gravity waves) and its effect on
climate. This field has always involved the application of the most
advanced computational technologies to science, and the
development of interdisciplinary models requiring specialists in many
fields (meteorology at various scales, hydrology, radiative transfer,
and boundary layer dynamics). His publications cover the breadth of
the field: they include papers on atmospheric climate, ocean
dynamics, cloudscale dynamics, non-hydrostatic models of gravity waves, computational methods, and
software engineering. Over the years, this breadth has evolved into an interest in the development of
modeling infrastructures, beginning with the creation of the GFDL Flexible Modeling System, of which
he is the chief architect, moving to technical leadership roles in international consortia to build similar
frameworks across multiple institutions (the Earth System Modeling Framework in the US, and the
Program for Integrated Earth System Modeling in Europe). Several key interdisciplinary consortia
centered on the University (the Carbon Modeling Consortium, the Carbon Mitigation Initiative) are
already built upon FMS-based modeling technologies developed under Balaji’s guidance. These
technologies aid the progress of Princeton research teams dispersed among multiple investigators, in the
building of complex coupled models to study ocean biogeochemistry, land biosphere dynamics,
hydrology, and other climate change impacts. The FMS has evolved into a unique tool for constructing
these complex models: nowhere else are these technologies available for immediate deployment. Balaji is
currently a principal investigator on an NSF SEIII grant to build a prototype environment called the Earth
System Curator. The Curator begins with the insight that a scientifically comprehensive description of a
model output dataset is the model configuration itself. By expressing this in a common language, it is
possible for either an exact model configuration, or a dataset from an existing model run, to be the result
of a scientific query. The Curator’s foundation is a database from which it is possible to extract on the
basis of such queries, either a model or an archived dataset for a particular experiment. Balaji is also a
principal investigator on the NASA-funded proposal MAPS to assemble standard coupled climate model
out of a range of ESMF-enabled model components.
Marcelo Barreiro, Research Associate
I completed my PhD in Physical Oceanography at
Texas A&M University in August 2003. In January
2004 I moved to Princeton University, where I started
working with Professor George Philander (Princeton
Univ.) and Ronald Pacanowski (GFDL). My research
aims to understand the evolution of the tropical oceanatmosphere state, and its role in the present and past
climates. Recent paleo-data suggests that the current
mean state of the tropical oceans with a cold tongue in
the east and a warm pool in the west may have been
different 5 to 3 million years ago. These data indicate that during the early-middle Pliocene the eastern
sides of the tropical oceans were as warm as the western sides and coastal upwelling regions did not exist.
Interestingly, the Pliocene was also the last period when the global climate was significantly warmer than
the present, even though the main external factors that determine climate -global geography and the
concentration of greenhouse gases- were essentially what they are today. Using atmospheric general
circulation models we have shown that a state of uniform tropical sea surface temperature warms the
climate by increasing the amount of atmospheric water vapor and decreasing the albedo of the Earth, thus
providing a new mechanism that could have contributed significantly to Pliocene warmth. I am now
investigating how this state of uniform tropical conditions can be induced and maintained. A recent study
with simple ocean models proposed that the degree of tropical east-west asymmetry can be varied by
changing the oceanic heat loss in high latitudes. Currently, the oceans gain heat in the equatorial regions
where cold waters upwell, and lose heat in high latitudes. Thus, were the oceans to lose less heat in high
latitudes, the need to maintain a balanced heat budget would require the ocean to gain less heat, reducing
the eastern cold tongue. I am currently studying if this mechanism can induce a state of uniform tropical
conditions. Initial results are encouraging, and show that a freshening of surface waters in the North
Pacific can induce such a state in a coupled ocean-atmosphere model. These experiments may not only
provide clues to understand the early Pliocene climate, but also demonstrate another way of rapid climate
change since the adjustment of the upper ocean occurs in the order of decades.
Cyril Crevoisier, Research Associate
After studying at the Ecole Normale Supérieure de Cachan in France,
I have obtained my PhD in remote sensing from the University of Paris
VII in October 2004. My thesis dealt with the estimation of
atmospheric CO2 distribution from space observations, using highspectral resolution infrared instruments. Three papers have been
published on this topic. In November 2004, I joined the Program in
Atmospheric and Oceanic Sciences at Princeton University. My
research projects deal with getting a better understanding of carbon
surface fluxes, with a focus on North America.
First, to exploit the measurements of CO2 vertical profiles by aircraft
and tall towers, that will soon be available at twenty locations across
North America, in the framework of the North American Carbon Program (NACP), I have developed a
direct carbon budgeting approach. Direct budgeting puts a control volume on top of North America,
balances air mass in- and outflows into the control volume and solves for the surface fluxes. This method
has been tested with CO2 simulations combining an atmospheric transport model, a land ecosystem model
and an oceanic model. It has been used to test the planned observation network and propose alternative
sites. This work has been presented at the Seventh International Carbon Dioxide Conference in October
2005 and a paper is about to be submitted to Tellus.
Secondly, I am developing a fire model for boreal forests to reinforce the land ecosystem model LM3,
which is developed at GFDL. Indeed, understanding the role of boreal forests in the global carbon cycle is
needed to accurately simulate the future behavior of these pools of carbon in the context of global
warming, and fires represent a major factor that influences the structure and carbon dynamics of the
boreal forest. An ignition function combining thermodynamic and human-related variables is being tested
against observations. A paper should soon be submitted.
These studies rely on simulations of atmospheric transport (MOZART model), air-land fluxes (LM3
ecosystem model) and oceanic air-sea fluxes (from the new GFDL model designed by John Dunne).
These models have been designed at Princeton University and GFDL and I am taking part in their
evaluation against in-situ observations of CO2 and O2 atmospheric concentrations. I am also part of a
project that will soon be submitted to NASA, dealing with the use of satellite observations in conjunction
with an oceanic and an atmospheric transport models to improve CO2 flux estimates over North-America.
Agatha M. de Boer, Research Associate
Agatha de Boer completed her Ph.D. in physical oceanography at
Florida State University in January 2003. She started a visiting scientist
research position in the AOSP/CICS program in March of that year.
Since arriving at Princeton, she has published 3 first author papers and
1 second author paper related to her dissertation work. Agatha’s
primary research interest is the interaction of the large scale ocean
circulation with climate, now and in the past. Her initial projects at
Princeton were with Robert Toggweiler and Daniel Sigman. The first
of these was to determine whether the observed link between ocean
temperature and deep ventilation in the paleorecord could be explained
by the fact that the sensitivity of density to temperature is higher in
warm climates, thereby increasing the thermal forcing in the ocean.
The second project aimed to understand the role of winds on the ocean circulation, as a provider of
energy, as a dynamic constraint, and through its effect on the thermodynamics. The above questions were
addressed with the help of GFDL’s ocean model, MOM4, coupled to a sea-ice model and energy balance
model for the atmosphere. With this work underway, Agatha started a collaborative project with Bill
Hurlin to test one of the hypotheses of her Ph.D. dissertation, i.e., that the opening of the Bering Strait
10,000 years ago lead to the stabilization of the thermohaline circulation and thus explains the relatively
stable climate of the Holocene. As set of experiments were carried out in a high resolution, realistic
topography version of the MOM4 models used in the previously mentioned process-orientated studies.
More recently, Agatha is involved in a study with Anand Gnanadesikan to asses the applicability to the
real ocean of the often used proportionality of the meridional density gradient to the overturning
circulation. Of the above projects, 1 paper has been submitted and 3 are pending.
Papers published and submitted while working at Princeton in the CICS/AOS program:
De Boer, A. M and D. Nof, 2004, The exhaust valve of the North Atlantic. Letter in J. Climate, 17,
417-422
Nof, D. and A. M. de Boer, 2004, From the Southern Ocean to the North Atlantic in the Ekman layer?
Bull. Amer. Meteor. Soc. 85, 79-87
De Boer, A. M and D. Nof, 2004, The Bering Strait 's Grip on the Northern Hemisphere Climate.
Deep-Sea Res., 51, 1347-1366
De Boer, A. M and D. Nof, 2005, The Island Wind-Buoyancy Connection. Tellus, 57A, Issue 5, 783797
De Boer, A. M, D. M. Sigman and J. R. Toggweiler, 2005, The effect of global ocean temperature
change on deep ocean ventilation. Paleoceanography, submitted.
Simon Donner, Research Associate
Simon Donner completed his PhD in Atmosphere and Ocean
Sciences at the University of Wisconsin-Madison at the end of
2002. He began working with Michael Oppenheimer at the
Woodrow Wilson School of Public and International Affairs in
early 2003. His research has focused on climate variability,
large scale nutrient cycling and the health of aquatic
ecosystems.
Over the past two years, he has refined hydrology and nutrient
cycling models developed during his PhD work to examine the
impact of climate variability and land use policy decisions on
the flux of nitrogen by Mississippi River the Gulf of Mexico.
One study found that the removal of nitrogen via in-stream
processes like denitrification and the associated N2O emissions can vary two- to three-fold annually due
to variability in rainfall. A second found that shifting from animal feed to direct human food cultivation in
the central U.S. could reduce the nitrate flux by the Mississippi River by over 40% and meet the EPA
goal of reducing the seasonal hypoxic zone in the Gulf of Mexico to less than 5000 km2. Ongoing
research is looking at how variability in precipitation [and climate indices] can be used to predict nitrate
export by large rivers and coastal health.
The rest of Donner’s time has been spent examining the possible impacts of climate variability and
climate change on the frequency of coral bleaching. A global study conducted in collaboration with the
NOAA Coral Reef Watch Program found that the majority of the world’s coral reefs will experience
annual or bi-annual bleaching within the next 30-50 years without an increase in their thermal tolerance
by 0.2 – 1.0 °C. The research is focusing specifically on the central Pacific (e.g. Republic of Kiribati)
where corals reefs are expected to be particularly vulnerable to variable ocean conditions and future
climate change.
Publications:
Donner, S,D. Surf or turf? Shifting from feed to food cultivation could reduce nutrient flux to the
Gulf of Mexico. Submitted to Global Environmental Change.
Boyer, E.W, Alexander, R.B., Parton, W.J., Li, C.S., Butterbach-Bahl, K., Donner, S.D. and Skaggs,
R.W. Modeling denitrification in terrestrial and aquatic ecosystems at regional scales: current approaches
and needs. Submitted to Ecological Applications.
Donner, S.D., Skirving, W.J., Little, C.M., Hoegh-Guldberg, O and Oppenheimer, M. Global
assessment of coral bleaching and required rates of adaptation under climate change. Global Change
Biology, in press.
Donner, S.D., Kucharik, C.J. and Oppenheimer, M. (2004) The influence of climate on in-stream
removal of nitrogen. Geophysical Research Letters, 31, L20509. Editor’s Choice in Science, November
19, 2004.
Stefan Gerber, Research Associate
Stefan Gerber completed his PhD Thesis at the University of
Bern, Switzerland in December, 2003. He started his postdoctoral
work at Woodrow Wilson School and the Department of Ecology
and Evolutionary Biology in July 2004, with Professor Michael
Oppenheimer and Professor Lars Hedin. His research focuses on
the implementation of a global model of a terrestrial nitrogen cycle
within the framework of the existing Earth System Model at the
Geophysical Fluid Dynamic Laboratory. Recently, an early version
of a nitrogen model has recently been put in place. It has a fixed
carbon/nitrogen stoichiometry in plants and in soil organic matter,
which allows for nitrogen imitation in plant uptake and litter
decomposition, while excess nitrogen is leaching as a function of water export. Today, the application of
fertilizers and anthropogenic emissions of reactive nitrogen greatly exceed pre-industrial bio-available
nitrogen deposition into terrestrial systems. While some of this nitrogen can be absorbed in vegetation and
soils, the remainder cascades through rivers, lakes, and estuaries, greatly disturbing these systems. On the
other hand, terrestrial sequestration of anthropogenic emissions of carbon dioxide also depends on the
supply of nitrogen. A coupled model of the terrestrial carbon and nitrogen cycles is therefore an important
tool to account for feedbacks in terrestrial carbon and nutrient cycle, and provides useful insights in the
response of the global biogeochemical cycles to changes caused by human activity.
Manuel Gloor, Research Scholar
Manuel Gloor studied physics at and has a PhD from ETH, Zurich, Switzerland
and is currently senior scientist at Princeton University. During his PhD he
developed and applied temperature microstructure and tracer techniques to study
dispersion of tracers in lakes. He was a Post-Doc at Princeton University in the
Programs of Atmospheric Sciences and Ecology and Evolutionary Biology. His
post doctoral work focused on data analyses and inverse modelling of the carbon
and oxygen cycles in the atmosphere and the oceans. He then held a post as senior
scientist at the max-Planck Institute for Biogeochemistry in Jena, Germany where
he helped initiate tall tower greenhouse gas measurement programs across
Eurasia. A focus of his current work is modelling of the carbon cycle on continents on regional and global
scales to assist the interpretation of carbon measurements on land with the ultimate aim to improve our
understanding of the interactions between the biosphere and climate.
Xianglei Huang, Research Associate
Xianglei Huang received his Ph.D. from California Institute of
Technology in June 2004. He joined AOS program at Princeton
University as a postdoctoral research associate in the same month. He has
been working on understanding the variability of the thermal IR
radiances and exploring efficient ways to use such observations to
evaluate the performance of the new GFDL AGCM, AM2. Huang studies
the temporal and spatial variability seen from outgoing thermal IR
radiances and then examines how good such variability could be
represented in current GCMs. With a careful treatment of the sampling
disparity between GCM and satellite observations, Huang has applied the “model-to-satellite” approach to
evaluate model performance with respect to satellite observations of IR radiances. This approach
computes synthetic IR spectra and narrowband radiances based on GCM outputs and then directly
compares these synthetic quantities with observed ones. This approach is affordable with today’s
computational power and effectively avoids the uncertainty resulted from ill-posed nature of IR retrieval.
Three subtasks have been carried out in since Huang’s arrival at Princeton University: (1) Temporal and
spatial variability of observed and simulated IR spectra; (2) Interannual co-variability seen from
comparisons among HIRS observation, AM2 simulation and reanalysis; (3) Quantify the source of errors
in AM2 simulated tropical clear-sky OLR; (4) the influence of ozone change on recent cooling of tropical
lower stratosphere. The results from subtask (1) and (2) were published on peer-reviewed journals. The
subtask (3) was also finished and the manuscript based on it is currently under peer review. The subtask
(4) is still an ongoing project and preliminary result will be presented in the incoming 2005 Fall AGU
conference.
Besides these activities, Huang has been a collaborator in two projects lead by J. Anderson and B.
Farrell at Harvard University, exploring the linear stochastic representation of variability seen in infrared
spectra. He has also co-authored three papers, ranging from the fast radiative transfer, variability in earth
upper troposphere, to the interaction between zonal flow and moist convections in Jovian atmosphere.
Publications:
Huang, X.L., and Y. L. Yung (2005), Spatial and spectral variability of the outgoing thermal IR
spectra from AIRS: A case study of July 2003, Journal of Geophysical Research - Atmospheres, 110,
D12102, doi:10.1029/2004JD005530.
Huang, X.L., B.J. Soden, and D.L. Jackson, Interannual co-variability of tropical temperature and
humidity: a comparison of model, reanalysis data and satellite observation, Geophysical Research Letters,
32, L17808, doi:10.1029/2005GL023375, 2005.
Soden, B.J., D.L. Jackson, V. Ramaswamy, M.D. Schwazrzkopf and X.L. Huang, The radiative
signature of upper tropospheric moistening, Science, 10.1126/science.1115602, 2005..
Natraj, V., X. Jiang, R.-L. Shia, X.L. Huang, J.S. Margolis, and Y.L. Yung, The Application of
Principal Component Analysis in Fast, Highly Accurate and High Spectral Resolution Radiative Transfer
Modeling: A Case Study of the O2 A-band, Journal of Quantitative Spectroscopy and Radiative Transfer,
95(4), pp. 539-556, November 2005.
Li, L., A.P. Ingersoll, X.L. Huang, Interaction of Moist Convection with Zonal Jets on Jupiter and
Saturn, Icarus, in press.
Submitted:
Huang, X.L., V. Ramaswamy and M. D. Schwarzkopf, Quantification of the source of errors in AM2
simulated tropical clear-sky OLR, submitted to Journal of Geophysical Research – Atmospheres
Laura Jackson, Research Associate
I arrived at Princeton University in August 2004 having completed my
PhD in Physical Oceanography at Liverpool University, UK. Since then I
have written and had accepted a paper based on my PhD work (see
below).
At Princeton I have been working in the joint Atmospheric and Oceanic
Sciences program with Princeton University and the Geophysical Fluid
Dynamics Laboratory (NOAA). I am involved in two projects: the
Gravity Current Entrainment climate process team and Eddy Mixed
Layer Interactions climate process team, although my work to date has mainly been on the former. This
past year, I have been working on documenting the sensitivity of overflows to the range of parameters of
our existing shear-mixing scheme; developing a new entrainment and shear-driven diapycnal mixing
parameterization; and implementing this new parameterization for use in our climate models. To develop
this new parameterization I have been running Large Eddy Simulations of shear-driven, stratified,
turbulent mixing. We will compare these results with both gravity current simulations from our
collaborators in Miami, and also with new and existing theories for gravity current entrainment.
In addition, as part of the other CPT project I will be a part of the effort at GFDL to implement and
evaluate the eddy-driven mixed layer restratification parameterizations now under development at MIT.
Publications:
Jackson, L., R. G. Williams, and C. W. Hughes, 2005: Topographic control of basins and channel flows:
the role of bottom pressure torques and friction. J. Phys. Oceanogr., accepted
Andrew Jacobson, Research Staff
Andy Jacobson earned undergraduate degrees in physics and
psychology at the University of Illinois in 1989. He then joined the
Peace Corps and left for Bénin, West Africa, where he taught
secondary school science. Thereafter he worked on famine early
warning systems for the U.S. Geological Survey and the World
Meteorological Organization in Niamey, Niger, for three years. He
earned a doctorate in meteorology at Penn State University in 2001,
for which he used techniques of acoustic tomography to study the
temperature structure of the North Pacific Ocean.
Jacobson has interests in applying mathematical and
statistical techniques to understanding observations of natural systems. Recently he has been studying
how ocean and atmospheric CO2 measurements can be interpreted in terms of surface fluxes. In
this work, observed spatial and temporal variations of CO2 concentrations are interpreted as fluid
transport in the atmosphere and ocean acting on terrestrial and oceanic sources and sinks. Other
interests include development of conceptual models of ecosystem structure in the ocean based on satellite
observations of ocean color.
Xianan Jiang, Research Associate
Xianan Jiang received his Ph.D. from the University of Hawaii at
Manoa in May, 2004, where he studied the dynamical mechanisms for
the tropical intraseasonal oscillation. In October 2004, he arrived at
Princeton University as a visiting scientist working with Drs. NgarCheung Lau and Isaac Held at GFDL. His study at Princeton is mainly
dedicated to a better understanding of the warm season climate regime
over the U.S. region and improvement of the GFDL AGCM in
simulating this regional climate system.
Since his arrival, Xianan Jiang has placed his main efforts on two
specific topics. The first one is on the mechanisms of the formation of Great Plains Low-Level Jet
(GPLLJ), which is one of the key components of summertime climate system over North America. Based
on successful simulation of the GPLLJ by the GFDL AGCM, the physical mechanisms for the formation
of this nocturnal low-level jet are re-evaluated in the context of existing theories. A simple model has also
been developed to serve this purpose. The results illustrate that both of the two mechanisms, i.e.,
alternative heating and cooling of sloping terrain and the inertial oscillation due to frictional decoupling,
play essential roles in shaping the observed GPLLJ. This part of work has been organized, and is to be
submitted for publication shortly.
Meanwhile, Xianan Jiang has been investigating the mechanisms for the diurnal cycle of summertime
rainfall over the U.S. Great Plains. The simulation of diurnal cycle of rainfall over this region remains a
great challenge for most of current AGCMs, including the GFDL AGCM. The AGCM simulated rainfall
tends to have an afternoon peak instead of a nocturnal one as in the observations. Currently, on one hand,
Xianan Jiang is diagnosing the observed data in order to identify the key factors responsible for the
precipitation regime in the real atmosphere; on the other hand, he is performing detailed comparison
between the AGCM simulation and its observed counterpart, so as to obtain some clues for improving the
model performance.
Publications:
Xianan Jiang, Ngar-Cheung Lau and Isaac. M. Held: AGCM simulated Great Plains Low-level Jet
and its Mechanisms. To be submitted.
Robert M. Key, Research Oceanographer
My research interests are rather eclectic, however a common thread
is the application of chemical tracers to the study large scale
oceanic processes. The scale of these projects is such that the
majority of my work tends to be highly collaborative. Recent
projects include investigation of the global radiocarbon distribution,
deriving a method to separate bomb-produces and naturally
occurring radiocarbon, using the bomb-radiocarbon inventory to
derive an improved estimate of the air-sea gas exchange rate,
estimating the global inventory of anthropogenic carbon dioxide
and investigating the flux of carbon dioxide between the
atmosphere and ocean, using various tracer distributions to
constrain and improve numerical ocean circulation models, quantification of the volume, distribution and
mixing of the primary oceanic water masses, determination of the Redfield ratio variation in the ocean ,
various studies of major nutrient cycling and investigating the influence of bottom topography of
advection and diffusion in an isopycnal coordinate ocean model.
By necessity, I have done a significant amount of fieldwork, including approximately 3 years at sea on
various oceanographic cruises, helping to generate the required volume of data. During the 1990s I led the
radiocarbon program for the World Ocean Circulation Experiment as well as participating in the U.S.
carbon effort for WOCE and JGOFS. Prior to that, the focus was on uranium-thorium series isotope
measurements. Since the end of the major global expeditions in 1998, I have focused that time on
assembling those data required to study biogeochemical process into an easily usable, uniform high
quality database. The first version of this database was released for public use in 2004 as GLODAPv1.1
and distributed through the Carbon Dioxide Information Analysis Center (CDIAC). This database and the
products derived from it provided the first three dimensional global description of the distribution and
inventory of numerous chemical tracers including dissolved inorganic carbon, alkalinity,
chlorofluorocarbons, and radiocarbon. This work continues and future versions will include additional
tracers as well as more data.
Lifeng Luo, Research Staff
Lifeng Luo received his Ph.D. in Environmental Sciences from
Rutgers University in May 2003 and started working at Princeton
University as a postdoctoral researcher with Prof. Eric F. Wood in
the Department of Civil and Environmental Engineering. He is
generally interested in prediction of the hydrological variables at
seasonal timescale. A fundamental challenge for seasonal
forecasting, in particular forecasting of hydrological extremes
(drought and flood), is to determine the extent to which climate can
be predicted on timescales of weeks to seasons, and to provide such
forecasts, and their quantified uncertainties that are useful to decision
making. One focus of his research is to study the predictability of the climate system at seasonal
timescale through modeling studies with general circulation models (GCMs) as they provide a useful
means to understand the natural variability and predictability of the real world. Another focus of his
research is to make useful hydrological predictions using current available tools. He has built a seasonal
hydrological forecast system that takes in seasonal forecasts from climate models such as the NCEP
Climate Forecast System (CFS), and produces a posterior forecast at suitable spatial scales through a
Bayesian merging method. Such a posterior forecast is then used to drive the VIC hydrological models to
make an ensemble forecast of surface hydrological variables such as streamflow and soil moisture. This
system has been applied over the Eastern US and produced near real-time forecast on a monthly basis.
Hindcasts with this system have shown skills and demonstrated the usefulness of such forecast.
Lifeng is currently preparing several papers that document his research in the last two years with two of
them on seasonal predictability, one on seasonal hydrological prediction and one on hydrological impact
of climate change over the Northeast US. He has helped in writing three research proposals submitted to
NOAA/OGP program and NASA/NEWS project, and two of them were funded and one is currently
pending.
Publications:
Lifeng Luo, Eric F. Wood and Ming Pan: A Bayesian approach for merging multi-model seasonal
climate forecasts. J. Climate, in review
Lifeng Luo and Eric F. Wood: Seasonal hydrologic forecasting with VIC model over the Southeastern
US. To be submitted to J. Hydrometeorology.
Seminar and Presentation:
L. Luo, E. F. Wood, C. T. Gordon and S. L. Malyshev: Precipitation variability and potential
predictability at seasonal-to-interannual timescale in the GFDL General Circulation Model, AGU,
Montreal, Canada, May 2004
L. Luo and E. F. Wood: A VIC-base seasonal hydrologic forecast system over the eastern US, 2nd
International workshop on HEPEX, Boulder, Colorado, July 2005
Sergey Malyshev, Research Staff
Sergey Malyshev received his Ph.D. in Geophysics from Institute of Experimental Meteorology,
Obninsk, Russia in 1995. His primary research interests are
simulation of climate, atmospheric circulation, its coupling to the
processes on the underlying land surface and to the carbon
balances in the Earth system.
He started working at Princeton University in 2001 as a research
staff member. His current primary activity is the development and
implementation of sophisticated land surface and vegetation model
in the framework of Geophysical Fluid Dynamics Laboratory
(GFDL) Flexible Modeling System (FMS). This is a part of a
larger effort to develop a comprehensive coupled
atmosphere/ocean/land climate model and Earth system model. As a result of this work, a paper
describing design and performance of the new LM3V land and biosphere model has been submitted to the
Global Biogeochemical Cycles and currently in review. Some exciting results regarding carbon balances,
influence of atmospheric CO2 concentrations on the land biosphere, and the role of human activity have
been already obtained with the new model and were presented at the Seventh International Carbon
Dioxide Conference. This work continues, with the current development of land model focusing on
improved representation of the soil moisture processes and associated feedbacks, and modeling river
transport. He is actively participating in the development of the atmospheric/coupler components of the
Earth system model.
He is also involved in a project studying predictability of Earth climate on the seasonal scale, in particular
the influence of soil moisture on the summer seasonal predictability. An important step in understanding
of the involved feedbacks in the atmospheric models and the potential of improving seasonal forecasts
was the collaborative Global Land-Atmosphere Coupling Experiment (GLACE). It resulted in a paper
published in Science emphasizing potential sensitive "hot spots" of the system, and the detailed
description of the findings is about to be published in the Journal of Hydrometeorology. As a
continuation of this study, he now works on some aspects of the seasonal forecasting with state-of-the-art
GFDL atmospheric model.
Recent Publications:
Anderson, J. L., V. Balaji, A. J. Broccoli, W. F. Cooke, T. L. Delworth, K. W. Dixon, L. J. Donner,
K. A. Dunne, S. M. Freidenreich, S. T. Garner, R. G. Gudgel, C. T. Gordon, I. M. Held, R. S. Hemler, L.
W. Horowitz, S. A. Klein, T. R. Knutson, P. J. Kushner, A. R. Langenhorst, N.-C. Lau, Z. Liang, S. L.
Malyshev, P. C. D. Milly, M. J. Nath, J. J. Ploshay, V. Ramaswamy, M. D. Schwarzkopf, E. Shevliakova,
J. J. Sirutis, B. J. Soden, W. F. Stern, L. A. Thompson, R. John Wilson, A. T. Wittenberg, and B. L.
Wyman, 2004: The New GFDL Global Atmosphere and Land Model AM2-LM2: Evaluation with
Prescribed SST Simulations. J. of Climate, 17, pp.4641-4673.
Randal D. Koster, Paul A. Dirmeyer, Zhichang Guo, Gordon Bonan, Edmond Chan, Peter Cox, C. T.
Gordon, Shinjiro Kanae, Eva Kowalczyk, David Lawrence, Ping Liu, Cheng-Hsuan Lu, Sergey
Malyshev, Bryant McAvaney, Ken Mitchell, David Mocko, Taikan Oki, Keith Oleson, Andrew Pitman,
Y. C. Sud, Christopher M. Taylor, Diana Verseghy, Ratko Vasic, Yongkang Xue, and Tomohito Yamada,
2004: Regions of Strong Coupling Between Soil Moisture and Precipitation. Science, 305, 1138-1140.
D. W. Keith, J. F. DeCarolis, D. C. Denkenberger, D. H. Lenschow, S. L. Malyshev, S. Pacala, and P.
J. Rasch, 2004: The influence of large-scale wind power on global climate. Proc. Nat. Academy of
Science, 101(46), 16115-16120.
Salvatore Manfreda, Research Associate
2001 - Degree in Civil Engineering (Hydraulics) cum lode, University of Basilicata, Italy.
2004 - Doctor of Philosophy, University of Basilicata, Italy.
Salvatore Manfreda has a broad interest in hydrology and ecohydrology with particular emphasis on soil moisture dynamics,
distributed modeling, rainfall modeling and flood event estimations.
He is interested in continuous hydrological simulations combining
stochastic rainfall models with distributed hydrological models for
flood event prediction. He has developed a rainfall-runoff distributed
model called DREAM that has been successfully applied over a
broad number of basins in Southern Italy.
His current research is focused on the description of the dynamic of
soil moisture in the spatial and temporal domain through the use of a
water balance model where the rainfall is represented as a stochastic
process in space and time. This topic has been developed in collaboration with Ignacio Rodríguez-Iturbe
deriving a simplified spatial-temporal soil moisture model driven by stochastic space-time rainfall
forcing. The model is mathematically tractable, and allows to explore analytically the spatial and temporal
structure of soil moisture fields, induced by the spatial-temporal variability of rainfall and the spatial
variability of vegetation.
The above results have then been used to derive the sampling requirements to estimate with a prescribed
statistical precision the average soil moisture over a give time interval (e.g., daily) and over a given area.
Recent publications:
Manfreda, S. & I. Rodríguez-Iturbe. On the Spatial and Temporal Sampling of Soil Moisture
Fields. (Submitted to Water Resources Research), 2005.
Manfreda, S., M. McCabe, E.F. Wood, M. Fiorentino and I. Rodríguez-Iturbe. Spatial Patterns of Soil
Moisture from Distributed Modeling. (Submitted to Advances in Water Resources), 2005.
Rodríguez-Iturbe, I., V. Isham, D.R. Cox, S. Manfreda, A. Porporato. Space-time modeling of soil
moisture: stochastic rainfall forcing with heterogeneous vegetation. Water Resources Research (in press),
2005.
Isham, V., D.R. Cox, I. Rodríguez-Iturbe, A. Porporato, S. Manfreda. Representation of Space-Time
Variability of Soil Moisture. Proceedings of the Royal Society A: Mathematical, Physical and
Engineering Sciences (in press), 2005.
Manfreda, S., M. Fiorentino, V. Iacobellis. DREAM: a distributed model for runoff,
evapotranspiration, and antecedent soil moisture simulation. Advances in Geosciences, 2, 31–39, 2005.
Manfreda, S., E.F. Wood, I. Rodríguez-Iturbe. Spatial patterns of soil moisture from distributed
modeling. Geophysical Research Abstracts, Volume 7, 2005.
Caylor, K.K., S. Manfreda, I. Rodríguez-Iturbe. On the coupled geomorphological and
ecohydrological organization of river basins. Advances in Water Resources 28(1), 69-86, 2005.
Scanlon, T.M., K.K. Caylor, S. Manfreda, S.A. Levin, I. Rodríguez-Iturbe, Dynamic Response of
Grass Cover to Rainfall Variability: Implications the Function and Persistence of Savanna Ecosystems.
Advances in Water Resources, 28(3), 291-302, 2005.
Vaughan Phillips, Research Staff
Dr V. Phillips received his PhD from the University of
Manchester Institute of Science and Technology (UMIST), UK, in
2001. He worked with Professors J. Latham, A. Blyth and T.
Choularton on development of an explicit microphysics model in
the atmospheric physics research group of the Physics Department
there. His research interests are:- cloud microphysics,
conversion of aerosols to hydrometeors, cloud dynamicsmicrophysics interactions, parametrisation of deep convection in
climate models, closure hypotheses for deep convection schemes
linking intensity of convection to large-scale flow, and the
interaction of aerosols with clouds during climate change.
An exciting development this year has been his participation in a team effort to develop a “doublemoment” treatment of cloud microphysics for the deep convection and large-scale cloud parametrisations
of the latest version of the GFDL General Circulation Model (GCM). The motivation for this effort is
the need for a capability to predict cloud radiative properties during climate change, in response to
anthropogenic modification of aerosol concentrations in the atmosphere. Such a “double-moment”
representation includes prediction of particle numbers, in addition to conventional scalars of mass mixing
ratio. This involves representing the natural diversity of nucleation pathways for formation of crystals
and droplets.
As a test-bed for development of double-moment codes for the GCM cloud schemes, a double-moment
bulk microphysics scheme has been created by Dr V. Phillips for GFDL CSRMs.
This scheme will soon be implemented within the framework of the Flexible Modeling System (FMS).
Microphysical modules (e.g. for preferential droplet evaporation during homogeneous freezing)
developed within the CSRM test-bed framework have already been applied directly to a new doublemoment version of the deep convection scheme of the GCM by Dr V. Phillips.
Selected publications:
J.-Y. Grandpeix, V. T. J. Phillips, and R. Tailleux “Improved mixing representation in Emanuel’s
scheme”, Q. J. R. Meteorol. Soc. , 130, pp 3207 (2004)
A. Khain, A. Pokrovsky, M. Pinsky, A. Seifert, and V. T. J. Phillips, “Simulation of effects of
atmospheric aerosols on deep turbulent convective clouds by using a spectral microphysics mixed-phase
cumulus cloud model. Part 1: Model description and possible applications”, J. Atmos. Sci., 61(24), 29632982 (2004)
Y. Ming, V. Ramaswamy, L. J. Donner and V. T. J. Phillips, “A robust parametrisation of cloud
droplet activation”, J. Atmos. Sci. In press (2005)
V. T. J. Phillips, S. C. Sherwood, C. Andronache, A. Bansemer, W. C. Conant, P. J. DeMott, R. C.
Flagan, A. Heymsfield, H. Jonsson, M. Poellot, T. A. Rissman, J. H. Seinfeld, T. Vanreken, V.
Varutbangkul and J. C. Wilson, “Anvil glaciation in a deep cumulus updraft over Florida simulated with
an Explicit Microphysics Model. I: The impact of various nucleation processes”, Q. J. R. Meteorol. Soc.,
131, 2019-2046 (2005a)
M. Salzmann, M. G. Lawrence, V. T. J. Phillips and L. J. Donner, “Modeling tracer transport by a
cumulus ensemble: lateral boundary conditions and large-scale ascent”, Atmos. Chem. Phys. Discuss., 4,
3381-3418 (2004)
Gwendal Rivière, Research Associate
I completed my PhD at the university of Pierre et Marie Curie in Paris
(France) in September 2002 on geophysical fluid dynamics where I was
supervised by Drs. Patrice Klein and Lien Hua. I have then done a first
postdoc at Centre National de Recherches Météorologiques in Toulouse
(France) on extratropical Atlantic storms with Dr. Alain Joly. Since January
2004, I am doing a second postdoc in Princeton (USA) funded by the
Atmospheric and Oceanic Sciences Program of Princeton University. I am
currently working on the Atlantic Storm-track variability and trends with
Dr. Isidoro Orlanski from the Geophysical Fluid Dynamic Laboratory
(GFDL).
The focus of my study is to better understand feedbacks of high-frequency
eddy activity onto the quasi-stationary circulation, particularly with regard
to the North Atlantic Oscillation (NAO) phenomenon. The NAO is the
principal mode of variability of the weather and climate over the north Atlantic domain and understanding its
mechanism is one of the major goals of the research community in climate sciences. Our methodology
consists in analyzing observations from NCEP reanalysis data and sensitivity runs from the high resolution
non hydrostatic regional model developed at GFDL that is called the ZETAC model.
Consistent with recent studies, our results show that the jet displacement characteristic of the NAO
phenomenon depends strongly on the dynamics of the high-frequency synoptic-scale waves and the way they
break. Positive and negative phases of the NAO are closely related to anticyclonic and cyclonic wave
breaking respectively. The original aspect of our work is to show with the help of sensitivity runs of the
ZETAC model that wave breaking over the Atlantic is strongly sensitive to the spatial and temporal
characteristics of the upper-level waves coming from the Eastern Pacific and North America. These results
could lead to the identification of precursors of the different NAO phases and are thus especially important for
predictability issues related to the climate in the Atlantic sector. It also can help to improve GCMs simulation
of the atmospheric low-frequency variability.
Before leaving GFDL at the end of the year, the rest of my work will consist in presenting the above results in
papers to be submitted for a refereed journal publication as well as in seminars and conferences as it will be
the case for example during the 2005 AGU Fall meeting.
Joellen L. Russell, Research Staff
Joellen Russell completed her Ph.D. at Scripps Institution of
Oceanography, UCSD in July 1999. She was then appointed a postdoctoral research fellow at the Joint Institute for the Study of
Atmosphere and Ocean at the University of Washington where she
worked with Professor J.M. Wallace. In September of 2002, she arrived
at Princeton University as a postdoctoral visiting scientist in the AOS
Program, jointly sponsored by Princeton University and GFDL/NOAA,
working with Dr. J.R. Toggweiler. She now works as a Research Staff
member of Princeton University, collaborating with Robbie
Toggweiler, Ronald Stouffer, Keith Dixon and Anand Gnanadesikan at
GFDL/NOAA and Stephen Pacala, Elena Shevliakova and Sergey
Malyshev at Princeton University.
Dr. Russell's research focuses on the carbon cycle impacts of the changes in the Westerly Winds, which
have moved poleward and increased over the last 30 years in both hemispheres, possibly as the first and
most ferocious of the impacts of global warming. She documented the impact of this shift in the Northern
Annular Mode on the northern hemisphere terrestrial vegetation and its subsequent impact on atmospheric
carbon dioxide and is collaborating with Elena Shevliakova, Sergey Malyshev and Stephen Pacala at
Princeton University to examine this process in the LM3V dynamic vegetation model. Dr. Russell is also
working on the impact of the shift of the wind over the Southern Ocean in creating and destroying the
water masses critical to the global carbon cycle, ocean circulation, and heat budget. The Southern Ocean
acts as the lungs of the ocean, "inhaling" oxygen and "exhaling" carbon dioxide (CO2) - determining the
partition of carbon between atmosphere and ocean. In pursuit of this research, Dr. Russell uses (and when
possible, collects) in situ and satellite measurements of the atmosphere, the ocean, and ocean bottom
sediments. She interprets these data using statistical analyses, ocean general circulation models, and
coupled climate models.
Related Publications:
Russell, J.L., & J.M. Wallace (2004), Annual carbon dioxide drawdown and the Northern Annular
Mode, Global Biogeochem. Cycles, 18, GB1012, doi:10.1029/2003GB002044.
Russell, J.L., R.J. Stouffer & K. Dixon, Intercomparison of the Southern Ocean Circulations in the
IPCC Coupled Model Control Simulations. J. Climate, accepted.
Russell, J.L., & J.M. Wallace, Carbon Dioxide Variability, Fire and ENSO Examined with a Simple,
One-Year Filter. Global Biogeochem. Cycles, accepted.
Delworth, T.L., et al., GFDL's CM2 Global Coupled Climate Models-Part 1: Formulation and
Simulation Characteristics. J. Climate, in press.
Gnanadesikan, A., et al., GFDL's CM2 global coupled climate models-Part 2: The baseline ocean
simulation. J. Climate, in press.
Griffies, S.M., A. Gnanadesikan, K.W. Dixon, J.P. Dunne, R. Gerdes, M.J. Harrison, A. Rosati, J.L.
Russell, B.L. Samuels, M.J. Spelman, M. Winton, and R. Zhang, 2005: Formulation of an ocean model
for global climate simulations , Ocean Science , 1, 45-79, 2005.
Toggweiler, J.R., J.L. Russell & S.R. Carson, The Mid-Latitude Westerlies, Atmospheric CO2, and
Climate Change during the Ice Ages, Paleoceanography, accepted.
Russell, J.L., K. Dixon, A. Gnanadesikan, R. Stouffer & J.R. Toggweiler, The Southern Hemispherre
Westerlies in a Warming World: Keeping the Door Open to the Deep Ocean. GRL, submitted.
Russell, J.L., A. Gnanadesikan & J.R. Toggweiler, Impact of Westerly Wind Position on the
Circulation of the Southern Ocean. J. Climate, in review.
Elena Shevliakova, Research Staff
Elena Shevliakova graduated from Moscow Institute of Physics and Technology in 1990, where she
studied applied physics and mathematics with the concentration on the ocean acoustics. She received
her Ph.D. from Carnegie Mellon University (CMU) in 1996. She was appointed a post-doctoral
research fellow at the CMU Center for Integrated Study of the Human
Dimensions of Global Change where she continued her research on application
of statistical methods for modeling the impacts of climate change on terrestrial
distributions of vegetation. In 1999 she joined Department of Ecology and
Evolutionary Biology at Princeton University as a research stuff member of Dr.
Pacala laboratory.
Dr. Shevliakova's research focuses on the study of the global biosphere-climate
interactions, with the emphasis on development of biosphere models and their
applications to the issues of global environmental change. For the past 5 years
she worked toward understanding of physical, ecological and biogeochemical aspects of land surface
dynamics. During this time she served as a co-leader of the GFDL-Princeton University land model
development team and worked on the implementation and evaluation of the new dynamic global land
model LM3V. She is planning to use the new model to systematically examine the terrestrial carbon
dynamics, the ecological impacts of climate change and the biosphere feedbacks on climate. She is
collaborating with a number of scientists at GFDL, Princeton University and University of New
Hampshire on the implementation and development of new capabilities in the land model and its
integration into the GFDL Earth System Model.
Related Publications:
Shevliakova, E., S.W. Pacala, S. Malyshev, G.C. Hurtt, P.C.M. Milly, J. P. Caspersen, P.C.D. Milly,
L. Thompson, C Wirth and K.A. Dunne (2005). "The Land Carbon Cycle and Vegetation Dynamics in
the Global Dynamic Land Model LM3V", submitted to Global Change Biology.
Hurtt, G.C., S. Frolking, M. G. Fearon, B. Moore III, E. Shevliakova, S. Malyshev , S. Pacala , R. A.
Houghton (2005). The underpinnings of land-use history: three centuries of global gridded land-use
transitions, wood harvest activity, and resulting secondary lands, submitted to Global Change Biology.
Shevliakova (2002). "Modeling Potential Impacts of Climate Change on the Spatial Distribution of
Vegetation in the US with A Probabilistic Biogeography Approach", in Wildlife responses to Climate
Change: North American Case Studies, Eds. S. Schnider and T. Root, Island Press.
Delworth, T.L. A. J. Broccoli, A. Rosati, R. J. Stouffer, V. Balaji, J. T. Beesley, W. F. Cooke, K.W.
Dixon, J. Dunne, K. A. Dunne, J W. Durachta, K.L. Findell, P. Ginoux, A. Gnanadesikan, C.T. Gordon,
S.M. Griffies, R. Gudgel, M. J. Harrison, I.M. Held, R. Hemler, L. W. Horowitz, S. A. Klein, T.R.
Knutson, P.J. Kushner, A. L. Langenhorst, H.-C. Lee, S.J. Lin, J. Lu, S. L. Malyshev, P.C. Milly, V.
Ramaswamy, J. R. , M. D. Schwarzkopf, E. Shevliakova, J. Sirutis, M. Spelman, W. F. Stern, M.
Winton, A. T. Wittenberg, B. Wyman, F. Zeng, R. Zhang, 2005. "GFDL's CM2 Global Coupled
Climate Models - Part 1: Formulation and Simulation Characteristics", (accepted to Journal of Climate).
Jennifer Simeon, Professional Technical Staff
I graduated with a M.S. in Oceanography from Oregon
State University. I am interested in utilizing ocean
tracers as a tool for understanding ocean circulation, as
well as ocean-atmosphere interaction.
My graduate studies focused upon developing optical
tracers to investigate flows on a continental shelf. My
current research concerns the Sub-Antarctic Mode Water
(SAMW) formation and pathways. Using tracers within
a suite of models that has varying global overturning
circulation states, these potential scenarios are explored
to gain insight for the ocean response to climate change.
Publications:
Simeon, J., C. Roesler, W.S. Pegau, and C. Dupouy (2003). Sources of spatial variability in light
absorbing components along an equatorial transect from 165E to 150W, J. Geophys. Res., 108:C10, 3333,
doi: 10.1029/2002JC001613.
Richard Slater, Prof. Technical Staff
I grew up in northern Illinois and attended college at Florida Institute of Technology from 1975-79,
majoring in physical oceanography. I began my career in “numerical
oceanography” by studying the tides in the Indian River in
Melbourne, Florida. I performed a numerical analysis of the tides
using data obtained from a tide gauge housed in the Crew team’s
boathouse.
I became involved in numerical modeling when I attended the
University of Chicago, working with Professor George Platzman on
my Master’s thesis: A Numerical Model of Tides in the Cretaceous
Seaway of North America. During my graduate school days, I spent
two summers working at Exxon Production Research Company in
Houston, Texas where I did some research on dissolved oxygen
distributions and organic carbon deposition in the Arabian Sea.
My interests now turning away from tides and towards biological and
chemical oceanography modeling, I started my Ph.D. thesis work on a model of oxygen in the ocean. In
1984 I moved to Princeton, working for Professor Jorge Sarmiento, both as job and to work more on my
dissertation research. However, I never did get working on my dissertation research and have been here
ever since. I attribute that mostly to having a job doing what I wanted to do, anyway (but it could always
be a little laziness on my part—nah).
In April of 1988, we started collaborating with Mike Fasham on ecosystem modeling, and shortly
thereafter, I had the Fasham model running in our 2-degree North Atlantic oceanic general circulation
model (OGCM). Since then, there has been much modeling of biology and chemistry put into our various
OGCMs. Recent technical work I have been doing has related to putting a generalized method to
incorporate tracer models into the Geophysical Fluid Dynamics Laboratory‘s (GFDL) Flexible Modeling
System (FMS)—basically, the Modular Ocean Model 4 (MOM4).
Qian (Scott) Song, Research Associate
Ph. D. in Physical Oceanography, Columbia University, 2004
M. Ph. in Physical Oceanography, Columbia University, 2003
M. A. in Physical Oceanography, Columbia University, 2001
B. S. in Oceanography, Ocean University of Qingdao, 1997
Since joining GFDL in July 2004, I have been working with
Anthony J. Rosati on three projects using the GFDL CM2.x
coupled climate model. Detailed description of the projects is as
follows.
(1) Assessment of the CM2 coupled climate model simulation of the North Pacific.
This project is part of the laboratory’s effort to evaluate the newly developed CM2 coupled models in
simulating the current climate system. My research is focused on the model simulation of the North
Pacific Ocean. The conclusions of this study are on the strength and weakness of the CM2.x models
in simulating the North Pacific climatology. In particular, we find the models produce reasonable
oceanic mass and heat transport, and due to the use of finite volume dynamic core in CM2.1 there is
substantial improvement in representation of the polar fronts and the subtropical gyre circulation over
CM2.0. However, there are biases of too diffused thermocline, deep winter mixed layer south of
Kurishio and large volume of the Subtropical Mode formation in the two models.
(2) Indian Ocean variability in the GFDL coupled model.
The 300-yr 1990-control simulation in CM2.1 provides an excellent opportunity for us to study the
dynamics of the interannual and decadal variabilities in the Indian Ocean. Our study is focused on the
Indian Ocean Dipole/Zonal Mode (IODZM), which is associated many debates about its air-sea
coupled dynamics and its relation with ENSO and is of much interest in the Indian Ocean research
community. We perform a composite analysis to explore the ENSO-IODZM relation. We find that
the westerly wind anomalies in the Western Equatorial Pacific, although may not be able to evolve
into full El Nino events, is effective in triggering the development of IODZM events. We also
propose that tropical storms occurring during boreal summer in the Eastern Tropical Indian Ocean
may be a mechanism that prevents the development of IODZM events when El Nino occurs in the
Pacific. The decadal modulation of the occurrence of IODZM events is also investigated.
(3) Effects of the ITF on the global climate.
Most previous studies on the ITF effects are conducted in ocean-only models. The few coupled model
studies only discussed the mean state difference ITF causes due to their short model integration. We
perform a perturbation experiment using the same model setting as the CM2.1 1990-control
experiment, except that the ITF is blocked. By contrasting the control experiment and the perturbation
experiment we study the ITF effects on the mean state, seasonal cycle and interannual variability of
the climate system.
J. Jason West, Research Staff
J. Jason West conducts interdisciplinary research addressing atmospheric
chemistry, and science and policy aspects of air quality management and
climate change. He came to Princeton in October, 2004, to work with V.
Ramaswamy and Denise Mauzerall of Princeton’s Woodrow Wilson School of
Public and International Affairs. He has also worked closely with Arlene Fiore
and Larry Horowitz of GFDL. His main research interest has been in
exploring whether methane emission reductions can be justified due to their
decreases in global background concentrations of tropospheric ozone. A first
paper on this topic (West & Fiore, 2005) showed that implementing low-cost
methane reductions using identified technologies can significantly reduce
global background concentrations of ozone, with substantial benefits to human
health and agriculture. This work has been extended over the past year by
using the MOZART-2 global atmospheric chemistry model to estimate the
effects of a 20% reduction in anthropogenic methane emissions on surface ozone concentrations, finding
a reduction of ~1 ppbv. These changes in surface concentrations were then used to estimate the avoided
incidences of premature human mortality, using ozone-mortality relationships from recent
epidemiological studies. We find that ~30,000 premature mortalities can be avoided in the year 2030, and
that when these benefits are monetized, they give ~$12 per ton CH4, which can justify the 20% methane
reduction. Our ongoing research has continued this theme by comparing the effects of reductions in
emissions of four ozone precursors (CH4, NOX, CO, and NMVOCs) on both surface ozone concentrations
and on radiative forcing of the global climate. In addition to this research, Dr. West has contributed to
two review papers addressing the international transport of air pollutants.
Publications:
West, J. J., and A. M. Fiore (2005) Management of tropospheric ozone by reducing methane
emissions Environmental Science & Technology, 39(13): 4685-4691, doi: 10.1021/es048629f.
West, J. J., A. M. Fiore, L. W. Horowitz, and D. L. Mauzerall (submitted) Mitigating ozone pollution
with methane emission controls: global health benefits, Proceedings of the National Academy of Sciences.
West, J. J., A. M. Fiore, V. Naik, L. W. Horowitz, D. L. Mauzerall (in preparation) Response of
surface ozone concentrations and radiative climate forcing to changes in ozone precursor emissions.
Bergin, M., J. J. West, T. J. Keating, and A. G. Russell (in press) Regional atmospheric pollution and
transboundary air quality management, Annual Review of Environment and Resources.
Keating, T., J. West, and D. Jaffe (2005) Air quality impacts of intercontinental transport, EM
(Environmental Management), 28-30, Oct., 2005.
Conference Presentations:
West, J. J., A. M. Fiore, L. W. Horowitz, D. L. Mauzerall ‘Control of methane emissions for ozone
air quality: global health benefits,’ MOZART Users’ Meeting, Aug. 2005, Boulder, CO.
West, J. J., A. M. Fiore, L. W. Horowitz, D. L. Mauzerall ‘Global health benefits from reductions in
background tropospheric ozone due to methane emission controls,’ AGU 2005 Joint Assembly, #A51B06, May 2005, New Orleans, LA.
West, J. J., A. M. Fiore, L. W. Horowitz, D. L. Mauzerall ‘Control of methane emissions for ozone
air quality purposes,’ Air Pollution as a Climate Forcing, A Second Workshop, Apr. 2005, Honolulu, HI.
West, J. J., A. M. Fiore ‘Reducing tropospheric ozone through methane mitigation: costs and
benefits,’ American Geophysical Union Fall Meeting, #A23A-0770, Dec. 2004, San Francisco, CA.
Youlong Xia, Research Staff
I arrived at CICS of Princeton and NOAA Geophysical Fluid
Dynamics Laboratory (GFDL) in December of 2003. Since then I
have published five papers and submitted one paper (in revision).
In CICS, I am focusing on my research project, building a realtime national streamflow information system for the US, based
on the GFDL LaD (Land Dynamics) model (LM2p7 and LM3w)
and NASA NLDAS (North American Land Data Assimilation
System) data set. This project will provide provide a streamflow
information system to meet society’s needs for water resource
management and use.
Calibration of GFDL land models (LM) is important for establishing a Real-time National Streamflow
Information System and for development of the GFDL coupled climate model. Both old (LM2) and new
(LM3) versions of the GFDL LM have many uncertain and unmeasureable model parameters. The
purpose of calibrating GFDL LMs is to reduce the uncertainties of these model parameters and to obtain
best performance for our research purposes.
To overcome disadvantages and limits of the manual calibration method used by Milly and Shmakin
(2002), we applied an automatic calibration method (very fast simulated annealing, or VFSA) to tune
GFDL LMs. To ensure the reliability and efficiency of the algorithm for our application, we have
performed many sensitivity tests with respect to VFSA parameters. Additionally, Xia has used this
algorithm to develop new methods to correct precipitation bias arising from gauge undercatch and
orographic effect, respectively. These methods integrate VFSA, LM2, and observed streamflow, and have
been applied on national and global scales. This method has been tested in the east of the United States by
use of the NLDAS (North Land Data Assimilation System) data set for the period from 1997 to 2002. The
results show that this method is able to correct gauge bias caused from wind-blowing, wet loss and
evaporation loss. A manuscript has been submitted to JGR-atmosphere (in revision). For global
topographic effect on precipitation data, a topographic bias adjustment method combining VFSA, LM2,
observed streamflow, and topographic variance is used. The primary results show that this method can
adjust topographic bias for global precipitation data because comparison of corrected precipitation and
PRISM (see http://www.ocs.orst.edu/prism/) data is very consistent. The draft about this work is
progressing.
These methods reduce forcing data errors (i.e., precipitation) and improve streamflow simulations in the
United States and globally. At the same time, GFDL land dynamics model (LM2) is also well optimized.
This optimization technique and work experiences from LM2 work now are being transferred to optimize
a preliminary version of the new GFDL land model (LM3W) with respect to hydrological and soil
physics processes. Eventually, this algorithm can be used to tune new land-vegetation dynamics model
(LM3) consisting of LM3W used as water component and LM3V used as dynamic vegetation component.
Recent Publications:
Xia, Y., Z. L. Yang, P. L. Stoffa, M. K. Sen, 2005a: Using different hydrological variables to assess
the impacts of atmospheric forcing errors on optimization and uncertainty analysis of the CHASM surface
model at a cold catchment, J. Geophys. Res., 110, D01101, doi:10.1029/2004JD005130.
Xia, Y., 2005: Optimization and Uncertainty Estimates of WMO Regression Models for
Precipitation-Gauge Bias in the United States, J. Geophys. Res. (in revision).
Jianjun Yin, Research Associate
Jianjun Yin received his Ph.D from University of Illinois at UrbanaChampaign in October 2004, majoring in climate dynamics and
modeling. He arrived at AOS/GFDL in fall 2004 as a postdoctoral
research associate, working primarily with Ronald Stouffer and also
with several other scientists at GFDL. Jianjun’s research subject is
the Atlantic Thermohaline Circulation (THC). So far he has finished
one project and has two ongoing ones.
Since his arrival, Jianjun has intensively participated in the data
analyses of the CMIP/PMIP coordinated “water-hosing”
experiments. These experiments were designed to systematically
study the sensitivity of the THC to external freshwater forcings. Jianjun, together with other co-workers,
has intercompared the simulations by 14 climate models worldwide, and evaluated the robustness of
particular features across the model results. The uncertainties in modeling the THC have been greatly
reduced in the multi-model ensemble mean. A paper describing the findings has been accepted by Journal
of Climate for publication.
Jianjun is currently leading two other projects: evaluating the uncertainty induced by the virtual salt flux
assumption in the climate simulations and studying the stability of the THC under very large freshwater
perturbations. He has found that a virtual salt flux version of the GFDL CM2.1 can give remarkably
similar simulations about the climate and climate changes with those from a freshwater flux version. But
some notable difference has still been identified. A paper that documents the findings is to be submitted to
Journal of Physical Oceanography. A CMIP “partially-coupled” experiment with the GFDL CM2.1 has
also been planed as one of Jianjun’s research activities at AOS/GFDL.
Publications:
J. Yin, R. J. Stouffer, M. J. Spelman and S. M. Griffies: Evaluating the Uncertainty Induced by the
Virtual Salt Flux Assumption in the Climate Simulations and Projections with a Coupled AtmosphereOcean General Circulation Model. Journal of Physical Oceanography (To be submitted).
R. J. Stouffer, J. Yin, J. M. Gregory, K. W. Dixon, M. J. Spelman, W. Hurlin, A. J. Weaver and
participating groups: Investigating the Causes of the Response of the Thermohaline Circulation to Past
and Future Climate Changes. Journal of Climate (In press).
Rong Zhang, Research Staff
Rong Zhang completed her Ph.D. at Massachusetts Institute of
Technology in September 2001. In January 2002 she arrived at
Princeton University as a postdoctoral visiting scientist in the AOS
Program, jointly sponsored by Princeton University and GFDL/NOAA,
working with Dr. Geoffrey Vallis at the AOS Program. Since January
2004, she worked as a Research Staff Member of Princeton University,
collaborating with Dr. Geoffrey Vallis at the AOS Program and Dr.
Thomas Delworth at GFDL/NOAA. She worked on three major
research projects. In the first project, Rong Zhang and Geoffrey Vallis
explored the mechanism of the Gulf Stream separation and the
existence of cyclonic Northern Recirculation Gyre (NRG) with a simple coupled model and developed a
theory identifying the ocean bottom vortex stretching induced by downslope deep western boundary
current (DWBC) as the key mechanism. In the second project, Rong Zhang and Geoffrey Vallis found
that coherent large-scale low frequency variability in the North Atlantic, including variations of
thermohaline circulation, DWBC, NRG and Gulf Stream path, can be induced by the observed highlatitude oceanic Great Salinity Anomaly events; on multidecadal timescales the positive (negative) Great
Salinity Anomaly phase, associated with more (less) Iceland sea ice extent, leads Labrador Sea surface
cooling (warming) and a positive (negative) North Atlantic Oscillation phase. The multidecadal variations
of the Iceland sea ice extent may have contributed to the observed Atlantic Multidecadal Oscillation
(AMO). In the third project, using a newly developed coupled ocean-atmosphere model (GFDL CM2.0),
Rong Zhang and Thomas Delworth investigated the global scale response of the climate system to a
substantial weakening of the Atlantic thermohaline circulation. The global response involves a southward
shift of the intertropical convergence zone (ITCZ) over both the Atlantic and Pacific sectors, an El Nino
like condition in the southern tropical Pacific, a La Nina like condition in the northern tropical Pacific,
and weakened Indian and Asian summer monsoons, consistent with the global-scale synchronization of
millennial-scale abrupt climate change as indicated by paleoclimate records. Recently, Rong Zhang and
Thomas Delworth have been working on a new project, i.e. the impact of Atlantic Multidecadal
Oscillation (AMO) on the 20th century climate variability.
Recent Publications:
Zhang, R., and T. Delworth, 2005: Simulated Tropical Response to a Substantial Weakening of the
Atlantic Thermohaline Circulation. Letter in Journal of Climate, 18, 1853-1860 .
Zhang, R., and G. K. Vallis, 2005: Impact of Great Salinity Anomalies on the Low Frequency
Variability of the North Atlantic Climate. Journal of Climate. In Press.
Zhang, R., and G. K. Vallis, 2005: The Role of the Deep Western Boundary Current in the Separation
of the Gulf Stream. Journal of Physical Oceanography. Under Review.
Research Grant:
Co-PI of the NSF grant OCE-0351383: Mechanisms of Decadal Variability in the North Atlantic: The
Thermohaline Circulation, Great Salinity Anomalies, and Gulf Stream Path. Awarded by NSF OCE in
Feb. 2004, and funded for three years with total of $ 444,253.
Ming Zhao, Research Associate
Ming Zhao received his PhD from the University of British
Columbia in September, 2003. During his PhD work, Ming was
involved in a Canadian project “Modeling Clouds and Climate
(MOC2)”. After his PhD, he continued his work for MOC2 in
Canadian Centre for Climate Modeling and Analysis (CCCma)
from Oct. 2003 to Jan. 2004. Starting from Feb. 2004, Ming joined
the GFDL Climate Process Team (CPT) and has been serving as
the GFDL's liaison to the atmospheric CPT project on “LowLatitude Cloud Feedbacks on Climate Sensitivity”. Ming’s research
interests include atmospheric moist convection, clouds and their
representations in large-scale and global climate models.
Ming’s work includes both supporting and original research components. Ming supports the GFDL
participation in the atmospheric CPT by providing a variety of GFDL model output, carrying new
simulations, analysis, implementing and testing new parameterization schemes in GFDL AM2. He also
created and maintained a CPT@GFDL web-page to assemble simulation data, display results and
efficiently communicated with the rest of CPT. Please see http://www.gfdl.noaa.gov/~miz for a detailed
description of the projects that Ming has been working on.
Under the supervision of Isaac Held, Ming is also pursuing original researches on simulations of largescale tropical atmospheric circulation with idealized configurations. They include dynamical radiativeconvective equilibrium, non-rotating mock Walker circulation and aqua-planet Hadley circulation
simulations. These idealized experiments are part of our effort to bridge the gap between our
understanding and the ever-complicated climate simulation. Comparing different GCMs in these idealized
simulations may offer new and simpler ways to highlight and understand the model differences.
Publications:
Wyant, M. E., C. S. Bretherton, J. T. Bacmeister, J. T. Kiehl, I. M. Held, M. Zhao, S. A. Klein, and B.
A. Soden, 2005: A comparison of tropical cloud properties and responses in GCMs using midtropospheric vertical velocity. Climate Dyn., submitted 8/05.
Held, I, M, M. Zhao and B. Wyman 2005: Radiative-convective equilibrium using GCM column
physics, J. of Atmos. Sci., to be submitted.
Zhao, M, I. M. Held and B. Wyman 2005: The role of atmospheric cloud radiative forcing in an
idealized Hadley circulation, manuscript in preparation.
Rongrong Zhao, Research Associate
Before being a postdoctoral researcher of Program in
Atmospheric and Oceanic Sciences in December 2004, I was
a doctoral candidate in Mechanical and Aerospace
Engineering Department of Princeton University. The title of
my Ph.D dissertation is “High Reynolds Number Turbulent
Pipe Flow”. This is a project funded by Office of Naval
Research (ONR). High Reynolds number flow is of extreme
research interest because many industrial flows and most
geophysical flows are of this kind, but at the same time, reliable measurement results are very limited.
The study is done in Princeton Superpipe (a major facility in the nation for high Reynolds number flow
research), where I used miniature two dimensional hot-wire to measure turbulence quantities up to
Reynolds number of ReD=1x107. This is the highest Reynolds number ever achieved for the pipe flow,
and the data is expected to serve as a reference data set for the development of numerical simulation and
predictive methods for turbulence. Along with turbulence research, I am also very interested in
improvement of measurement techniques. I developed a new calibration method for crossed hot-wire
probe (one of the major measurement methods for turbulence), and the new method is believed to be more
accurate than traditional calibration methods. I also pointed out an important measurement uncertainty in
hot-wire experiments, which is often neglected by peer experimentalist but can lead to significant error in
certain flow conditions. Both are published in peer reviewed journals. I received my Ph.D from Princeton
University in January 2005.
Following my doctoral work, I joined GFDL in the hope of contributing my knowledge in turbulence to the
ocean and climate community. The project I am working on now is to develop suitable parameterization of
mesoscale eddies for upper ocean boundary. The flow in the top ocean receives much attention from the
scientists because it is the region where the coupling between ocean and atmosphere happens and most
numerical problems are encountered for current climate model. This work is a part of CPT-EMILIE
(Climate Prediction Team on Eddy-MIxed Layer IntEraction), which is established by the U.S. CLIVAR
program for linking process-oriented research and coupled climate model development.
In more detail, I use GFDL modular ocean model (MOM) to compute different idealized ocean domains.
By that, I study 1) the effects of eddies on the ocean mean circulation and 2) the dynamics of the
interaction between mesoscale eddies and boundary layer turbulence. I am running numerical simulations
with both high spatial resolutions and low spatial resolutions. High spatial resolution results are
considered as more realistic and used to study the dynamics of eddies. Low spatial resolution models are
run with typical spatial resolutions that is used in current climate model to target problems. The ultimate
goal is to develop physically sound subgrid scale parameterization for eddies and turbulence and improve
climate models.
Publications:
Rongrong Zhao and Alexander Smits, Two dimensional turbulence statistics in high Reynolds
number turbulent pipe flow. In preparation for J. Fluid Mech.
Rongrong Zhao and Alexander Smits, Binormal cooling effects for hot-wire measurement.
Experimental fluid mechanics, To appear.
Rongrong Zhao, High Reynolds Number Turbulent flow. Ph.D thesis, Princeton University, 2004
Rongrong Zhao, Junde Li and Alexander Smits, A New calibration method for crossed hot
wires, Meas. Sci. Technol. 15 No 9, 1926-1931.
Graduate Student
Bios
Gang Chen, Graduate Student
I am a 4th year graduate student in the AOS program. My interest is the
theory and modeling of the atmospheric general circulation. More
specifically, my thesis topic is to study the factors that control the midlatitude jet stream and the surface westerly positions.
In the atmospheric general circulation models (GCMs), the mid-latitude
jet in the southern hemisphere displays a robust poleward shift in
response to the global warming. This shift of zonal wind, projected
strongly onto the Southern Annular Mode (SAM), is simulated by a large
number of GCMs as well as seen in the observation. Despite this problem has been investigated in
relatively simple idealized models, it still remains a challenge to identify and isolate cleanly their
underlying mechanisms. The current work aims to explore the simplest case of the jet shift with the
surface friction, and hope to understand the factors determining the jet position in the global warming
simulations in a hierarchy of models.
We employ the GFDL atmospheric dynamical core forced by the Held-Suarez forcing available in the
Flexible Modeling System (FMS). As the surface friction is reduced, the mid-latitude jet displaces
poleward analogous to the global warming response. The effect of the surface friction is separated as the
friction on the zonal means and the friction on the eddies, and the poleward shift is found to be primarily
controlled by the friction on the zonal means. In addition, reducing the surface drag permits the
development of stronger barotropic flow that suppresses the mid-latitude eddies. More detailed
investigation indicates that the barotropic flow and the phase speed of the large scale eddies play
important roles in the jet shift. The gravity wave drag (GWD) can also cause the poleward jet shift,
implying the need of appropriate GWD parameterizations in tuning the GCMs. This result is to be further
studied with the realistic spatial distributions of the topography and the jet stream.
The nature of the jet shift involves the internal variability of the atmosphere. The first Empirical
Orthogonal Function (EOF) of zonal wind variations is often called the annular mode, and is an indicator
of climate change. We are currently developing a simple quantitative theory for the jet shift as well as the
annular modes. The notion is to idealize the upper troposphere as one shallow water isentropic layer
forced by the stochastic stirring. The simple model provides us some insights on the problem of the jet
shift in the development of GCMs.
Neven S. Fučkar, Graduate student
Ph.D. candidate, AOS Program, Princeton University
M.S. in Oceanography, Texas A&M University, 2003
B.S. in Physics, University of Zagreb, Croatia, 2000
The world oceans exert significant influence on the climate. In
concert with the atmosphere through lateral (primarily meridional)
and vertical transport of heat, freshwater and critical chemical tracers
the oceans make the Earth hospitable to our global society in the
present state. In such a planetary scale mosaic interesting and yet not
completely resolved question is the nature of interaction of ocean meridional overturning circulation
(MOC) and the largest ocean current in the world, the Antarctic Circumpolar Current (ACC).
My most recent research, under the supervision of Prof. Geoffrey K. Vallis, among other things addresses
the question of impact of MOC on the dynamics of ACC transport in an idealized coarse-resolution ocean
model. Currently, at the nexus of method is the use of the Modular Ocean Model version 4.0c (MOM4)
with analytically prescribed direct (wind stress) and restoring (temperature and virtual salinity) surface
boundary conditions. We began working with a single-basin configuration that includes the Southern
Ocean (SO) channel with a sill. Interesting result is substantial sensitivity of the ACC transport to the
Northern Hemisphere meridional temperature gradient (besides previously established sensitivity to the
SO winds). As the gradient decreases ACC transport increases. Hence this research represents an
opportunity to further understand and separate dynamical and thermodynamical mechanisms of ACC
transport and variability.
In the near future we plan to use also the Hallberg Isopycnal Model (HIM) to establish the level of
robustness of these conclusions by comparing z-level and isopycnal model results. Ultimately, we intend
to explore this point further with a hierarchy of idealized atmosphere-ocean-ice coupled models.
Resolving how these results fit into the overall picture of global climate and their implication for
understanding of paleoclimate records will benefit development of ocean and climate dynamics theory
and advance models. Also this progress could potentially enhance climate predictability and clarify
aspects of global climate change.
Edwin Gerber, Graduate Student
Applied and Computational Mathematics Program, Princeton University
B.S. Mathematics and Chemistry, 2000 University of the South
M.A. Applied Mathematics, 2002 Princeton University
Mr. Gerber is pursuing his PhD thesis on intraseasonal variability in the
atmosphere with Geoffrey Vallis. He has developed a hierarchy of models
of the North Atlantic Oscillation (NAO) and annular modes, the dominant
large scale patterns of intraseasonal variability in the extratropics, with the
goal of better understand their spatial and temporal structure. Mr. Gerber
began his research with Dr. Vallis in early 2002, and plans to complete his dissertation in December 2005.
They have applied a bracketing strategy to the problem, in which a range of idealized models were
developed to explain key features of the variability. By adding and subtracting different elements of the
dynamics, they were able to isolate the essential processes that govern the patterns.
A barotropic model of the atmosphere was the starting point of their research, capturing both the basic
spatial and temporal structure of the NAO and annular modes. The model suggest that both are a direct
consequence of the “stirring” of the large scale flow by baroclinic eddies. The mode explicitly shows
how such stirring, as represented by a simple random forcing in the model, leads to a variability in the
zonal flow via a variability in the eddy momentum flux convergence. If the stochastic forcing is
statistically zonally uniform, then the resulting patterns of variability (i.e., the empirical orthogonal
functions, EOFs) are zonally uniform and the pressure pattern is dipolar in the meridional direction: an
annular mode. If the forcing is enhanced in a zonally localized region, thus mimicking the effects of a
storm track over the ocean, then the resulting variability pattern is zonally localized, resembling the NAO.
This suggests that the NAO and annular modes are produced by the same mechanism, and are
manifestations of the same phenomenon. The timescale of variability of the patterns is longer than the
decorrelation timescale of the stochastic forcing. This is a consequence of the fact that these patterns
characterize the zonal momentum in the atmosphere, the integral of the eddy momentum fluxes.
Integration strengthens the power of low frequencies, which are ultimately truncated by friction to
produce a red spectrum similar to that observed.
Results from the study of the barotropic model indicated that the basic spatial structure of the patterns, in
particular the meridional dipole of geopotential height and zonal velocity, could be explained in a more
idealized context. Gerber developed a series of analytic, purely stochastic models that show that the
spatial structure of the NAO and annular modes is a natural consequence of the conservation of mass and
zonal momentum and geometric constraints of the extratropical circulation.
Lastly, Gerber and Vallis have sought to verify the conclusions from the stochastic and barotropic models
in a dry primitive equation general circulation model. Annular mode and NAO-like patterns are found by
varying the degree of zonal asymmetry of the model's synoptic variability (that is, the model's storm
track) with idealized topography and heating anomalies designed to approximate land-sea contrast. Only
with the confluence of the right thermal and topographic forcing does a truly localized NAO-like pattern
appear. This NAO can be further understood in the context of the eddy life cycle; maximum variability of
the zonal flow is found in the exit region of the storm track, where eddy decay (and hence eddy
momentum fluxes) dominate. In this region the eddy driven jet can more fully separate from the
subtropical jet. This separation and merger is, in essence, the NAO.
The temporal structure of primitive equation model is richer than the barotropic model, as it is "self
stirring," producing its own baroclinic instability which can interact with the large scale variability. This
interaction extends the persistence of the annular modes and NAO though a feedback between the eddies
and large scale flow. Mr. Gerber is currently probing the sensitivity of this feedback to the model's
thermal forcing and to topography.
Arno C. Hammann, Graduate Student
Program in Atmospheric and Oceanic Sciences
Princeton University, Princeton NJ
B.A. in Geography
University of Cambridge, Cambridge, UK (2002)
My research in the past year was concerned with the dynamics and thermodynamics of the annual cycle
(of ocean temperatures, currents, and winds) in the tropical Pacific Ocean. While the interannual
variability in this region (El Niño-Southern Oscillation, ENSO) has been receiving a lot of attention from
the climate research community, many aspects of the annual cycle are still poorly understood. A better
understanding, however, is crucial both with respect to the interaction of the annual cycle with the mean
climate state and with ENSO-scale variability. In particular, current state-of-the-art coupled climate
models continue to exhibit biases in the mean climate state in the tropical Pacific and unrealistic annual
cycles involving, among others, a ‘double’ Intertropical Convergence Zone (ITCZ).
My research under the supervision of Prof. S. George Philander and Prof. Anand Gnanadesikan used the
CM2.1 coupled climate model developed at the Geophysical Fluid Dynamics Laboratory (GFDL) to
investigate the relative importance of diabatic and adiabatic processes in driving the annual cycle. While
it is clear that diabatic forcing (ultimately, solar radiation) sets the pace of the annual cycle, the largest
fraction of heat fluxes in the ocean results from internal ocean dynamics. It has previously been
recognized that the annually varying upwelling through the thermocline (forced by the annual cycle in
winds) is a dominant mechanism. However, it has become clear now that a second mechanism is equally
important: meridional movement of the equatorial cold tongue. The interplay of these two processes is
crucial in allowing an annual cycle to be forced at all at the equator, where the annual solar forcing
actually vanishes.
Yi Huang, Graduate Student
I’m a third-year Ph.D. student of the Program in Atmospheric and
Oceanic Sciences of Princeton University. My research interest is
Climate Sensitivity, how the complex climate system responses and
equilibrates with respect to both natural and anthropogenic forcings
and how different climatic components exert their roles in the
process. This falls in the first of the CICS themes, Earth System
Studies/Climate Research.
The research I’ve been carrying on is about the roles of atmospheric
temperature and water vapor in influencing the Radiative Energy
Budget at the Top of the Atmosphere. Under clear-sky condition, atmospheric temperature and water
vapor are two major factors that affect the Outgoing Longwave Radiation (OLR). The spectral
dependence of OLR upon the vertical distributions of the two factors is a key element in the
understanding of their influence on the longwave radiation budget of the planet. Using the Geophysical
Fluid Dynamics Laboratory (GFDL)’s line-by-line (LBL) radiative transfer model as well as the GFDL
climate model’s longwave radiation parameterization, I examined the OLR sensitivities to temperature
and water vapor (defined as the partial differentials of OLR with respect to the variables), for three typical
atmospheres: tropics, mid-latitude summer and mid-latitude winter. The principle findings are: 1). Results
of OLR sensitivity do not differ with the longwave band approximation, nor different formulations of
water vapor continuum absorption cause significant difference in simulated OLR sensitivity. 2). Shown in
a GCM (General Circulation Model) climate sensitivity experiment, although the inclusion of water vapor
continuum is indispensable to properly simulate clear-sky OLR response to prescribed sea surface
temperature change, different continuum formulations yield negligible difference. 3). The numerically
calculated OLR sensitivity values are used to reconstruct the tropical annual mean OLR anomaly from the
anomalies of the surface and atmospheric conditions over the 1980-1999 period. The OLR anomaly time
series thus reconstructed agrees very well with that computed explicitly by climate model. 4). The above
finding enables the separation and analysis of the temperature and water vapor contributions to the OLR
variation, which shows that, in the lower and middle troposphere, temperature contribution dominates
water vapor contribution while in the upper troposphere, the two opposite contributions offset each other
almost completely. A paper has been drafted based on the above work and findings.
Sarah M. Kang, Graduate Student
Sarah Kang is a second year graduate student. During the first
semester, Kang took several classes that are required for the general
exam in next year. In numerical methods class, Kang has done a
research about how moisture is advected differently when different
advection schemes are applied using shallow water model. Kang was
able to capture several realistic characteristics from this simple model.
In second semester, Kang investigated the influence of aerosol on
precipitation over Sahel. To make a link between aerosol and
precipitation, Kang has worked on how aerosol affects the shortwave flux at the surface and how it
changes the sea surface temperature over North Atlantic Ocean and Indian Ocean.
Throughout the year, Kang has developed an interest in African climate change. The African Sahel
experienced a prolonged dry episode in the latter decades of the 20th century. It's surprising that every
model produces different trend for the next century. Especially, Japanese model says it'll get moistened
and GFDL model says it'll become drier catastrophically. To understand what is going on over Sahel,
Kang decided to use an intermediate complexity moist general circulation model to study what determines
the extent of precipitation movement, the position of ITCZ and the boundary of rainbelt.
Kang started working with a simplified moist GCM. Several experiments, like putting an idealized
rectangular continent and inputting seasonal variation by modifying solar flux as a function of time have
been done recently. These days Kang has been concentrated on the experiments taking heat out of the
southern hemisphere and put it hack to the northern hemisphere to make asymmetry in Hadley cells and
figure out how ITCZ moves.
Seoung Soo Lee, Graduate Student
I am a third-year grad student in AOS program at Princeton University,
working with Dr. Leo Donner as my advisor. I have studied the
interaction between aerosol and cloud. After industrialization around
the world, there has been an increase in aerosol mass and concentration.
Anthropogenic aerosols are typically in the submicrometer- to
micrometer-size range, suitable range to act as Cloud Condensation
Nuclei(CCN) [ Haywood and Boucher, 2000 ], which means human
activity can change cloud properties and hence climate. Anthropogenic
sources contribute almost as much as natural sources to the global aerosol amount[ Hansen et al. , 1997 ;
Robertson et al., 2001]. These newly added aerosols from anthropogenic sources are considered to
partially offset global warming by reflecting more incoming solar radiation. This is the aerosol direct
effect on climate and leads to uncertainties in predicting climate. But the uncertainties are higher in
aerosol indirect effect, because the indirect effect accompanies cloud microphysics. Aerosols can act as
CCN, and therefore, the change in aerosol properties, such as number concentration, can change cloud
development and a role of clouds in climate. The increase in aerosol number concentration induces a
decrease in droplet size, increase in reflected solar radiation (first aerosol indirect effect) and precipitation
suppression (second aerosol indirect effect). Ramanathan et al. [2001] pointed out the second indirect
effect on precipitation and radiation spin down the hydrologic cycle and increased reflection of solar
radiation. But my study shows contrary results to traditional precipitation suppression, indicating the role
of aerosol can differ in deep convections.
Cynthia A. Randles, Graduate Student
Ph.D. Candidate, Atmospheric and Oceanic Sciences Program
M. A. Princeton Atmospheric and Oceanic Sciences Program, 2003
S. B. in Earth, Atmospheric & Planetary Sciences, MIT, 2000
CICS Research Theme: Earth System Studies/Climate Research
Thesis Topic: Carbonaceous aerosol effects on climate
Atmospheric aerosols play several important roles in the climate
system. By scattering and absorbing incoming solar radiation, they directly impact the amount of
radiation reaching the surface. Indirectly, they can modify the microphysical properties of clouds,
increasing cloud brightness and decreasing precipitation. Absorbing aerosol, such as black carbon (BC),
dust, and some organic carbon (OC), can have an additional “semi-direct” effect. The semi-direct effect of
absorbing aerosol causes a redistribution of warming in the atmosphere as the aerosol layer absorbs
incoming solar radiation. This can lead to a warming in clouds that can result in a partial evaporation that
reduces the cloud albedo, which in turn warms the surface.
Aerosol can exist as an external mixture composed of separate particles of dust, sea salt, OC, BC, and
sulfate, or these constituents may be combined in random ways to form an internal mixture. The
chemical composition of aerosol, which is a function of mixing state, will determine its refractive index.
Along with particle shape and size, the refractive index will dictate the amount of light a particle will
scatter and absorb at a given wavelength of light. In addition, the composition of the aerosol will
determine its hygroscopicity, or how much water it will take up in a humid atmosphere. Aerosol
hygroscopicity can then influence chemical composition and shape, further changing the optical
properties of the aerosol.
I began my thesis research in 2001 working with V. Ramaswamy of the Princeton AOS program and
Lynn M. Russell from Princeton’s Chemical Engineering Department. My research focused on studying
the effects of mixing water-soluble organic compounds (WSOC) with sea-salt aerosol, focusing on
changes in aerosol hygroscopicity and the resulting changes in optical properties. This research was
motivated by the fact that organic compounds may account for up to 50% of marine aerosol mass, and
that many WSOC, when mixed with sea-salt aerosol, will reduce water uptake and therefore the scattering
ability of aerosol, thus reducing the cooling from sea-salt predicted by climate models which do not
include this effect of the WSOC. By analogy, WSOC can also become associated with sulfate particles,
which also experience a reduction in hygroscopic growth and scattering when mixed with WSOC. Thus,
it is likely that if WSOC are associated with sulfates and sea salt, the global radiative cooling associated
with organic compounds is overestimated because of inadequate accounting of their hygroscopic growth
and absorption effects, thus making it imperative that evaluations of aerosol climate effects consider these
physical processes explicitly. This research culminated in a paper which was published in Geophysical
Research Letters in 2004.
In the summer of 2004, I was given the opportunity to participate in the International Consortium for
Atmospheric Research on Transport and Transformation (ICARTT) Chemistry of Halogens at the Isles of
Shoals (CHAiOS) field study on Appledore Island, Maine with Lynn Russell. This project augmented the
AIRMAP observatory on Appledore Island, 12 km off the coast of New Hampshire, with an extensive
suite of aerosol and trace gas measurement systems. Deployed systems for trace gas measurements
included long-path and multi-axis DOAS, automated GC-MS, PTR-MS, mist chambers and filter packs.
Aerosol systems included an APS, a SMPS, cascade impactors and bulk aerosol filters. I was responsible
for the aerosol measurements with the APS, which measures aerosol particles > 1 micron in diameter, and
the SMPS, or scanning mobility particle system, which measured aerosol size distributions for aerosol < 1
micron in diameter. In addition, 12-hour aersol bulk filter samples were taken for later analysis at the
Scripps Institution of Oceanography (SIO) using a Fourier Transform Infrared Spectrometer (FTIR) to
look for organic functional groups.
Currently, I am working on studying the effects of black carbon (BC) aerosol over China and India using
the Geophysical Fluid Dynamics Laboratory’s (GFDL) AM2 Global Climate Model (GCM). I am
looking at the climate effects of increasing aerosol absorption by increasing the fraction of BC versus
scattering anthropogenic aerosol (sulfate and organics), and of the effects of increasing the total column
burden of absorbing aerosol (BC). In this study, AM2 is being run with fixed sea-surface temperatures
(SSTs) and greenhouse gasses (GHGs) so that only the impact of aerosol changes is considered. The
purpose is to understand how the model response, particularly surface temperature, clouds, and the
hydrologic cycle, is altered with changes in the heating rate of different atmospheric layers. I am
currently investigating changes in radiative forcing resulting from increasing the single scattering albedo
throughout the atmospheric column and layer-by-layer over China.
I am also looking at the effects of biomass burning OC and BC over Southern Africa using a new GFDL
model which includes interactive aerosol. Of particular interest will be the sensitivity of radiative forcing
and climate response to the vertical profile of the aerosol and to the mixing state of the biomass burning
aerosol. The parameter space for these sensitivity studies can be limited by employing measured data. In
particular, I will use ground-based remote sensing (AERONET) and satellite (TOMS) measurements to
constrain the range of optical depths and single scattering albedo considered.
Publications:
Randles, C. A., L. M. Russell, and V. Ramaswamy (2004), Hygroscopic and optical properties of
organic sea salt aerosol and consequences for climate forcing, Geophys. Res. Lett., 31, L16108,
doi:10.1029/2004GL020628.
Poster Presentations:
Randles, C. A., L. M. Russell, and V. Ramaswamy (2004), Hygroscopic and optical properties of
organic sea salt aerosol and consequences for climate forcing, 8th International Global Atmospheric
Chemistry (IGAC) Conference, Christchurch, New Zealand.
Agnieszka Smith-Mrowiec, Graduate Student
Ph.D. Candidate, AOS Department at Princeton University
Ph.D. in Geophysics at Warsaw University (October 2001 – August
2002, discontinued)
M. Sc. in Physics (2001) at Warsaw University, Poland
Hurricanes wreak devastation on costal communities each year,
causing loss of life and billions of dollars of damage. Nevertheless,
many basic aspects of the dynamics that control the formation and
steady state parameters of a hurricane are not understood and hence
not predictable. A typical hurricane is nearly axisymmetric, and has an
axial wind profile that achieves a maximum at some well-defined distance from its center. This distance
is called the Radius of Maximum Wind (RMW), and is one of the most important dynamical parameters
necessary to describe any given hurricane. Predicting it would be invaluable when assessing possible
disaster range at landfall. Not much is known about what sets the RMW. It is clear, though, that there is
no simple correlation between RMW and other obvious dynamical parameters, such as maximum wind
speed, minimum central pressure, or environmental conditions such as sea surface temperature.
Smith-Mrowiec began her PhD study two years ago, and has been working with Garner and Pauluis to
investigate what sets the RMW. This is an ongoing project. The investigation involved the use of an
axisymmetric, nonhydrostatic hurricane model (ZETAC). The resolution of the model for the preliminary
study was 2.5 km and the domain size was 500 km. Initial simulations were made for 15 days of hurricane
life, with the objective of generating a steady state. The preliminary study revealed, however, that even
generating a steady state was very challenging. The model was set up to run in both 2D and 3D. 3D is
interesting because convective dynamics is altered and also the azimuthal wave instability can be
observed.
Once the intermediate studies are completed (effects of larger domain size, higher resolution (1 km) and
generating a set of self-consistent atmospheric states for each sea surface temperature that would be used),
the next step will be to study the correlation of the RMW with a quantity called Maximum Potential
Intensity (MPI - see Emanuel, 1988,1995, Holland 1996). Hurricanes derive their energy from the
thermodynamic disequilibrium between the tropical oceans and the atmosphere, and the MPI
quantitatively summarizes this. Emanuel's maximum potential intensity theory predicts an upper limit for
the maximum wind, depending mostly on the sea surface temperature, atmosphere temperature and the
efficiency of the heat conversion into wind energy. The Emmanuel theory will be used as a basis from
which to approach the underlying dynamics controlling the RMW.
References:
Emanuel, K. A., 1988: The maximum intensity of hurricanes. J. Atmos. Sci., 45
Emanuel, K. A., 1995: Sensitivity of tropical cyclones to surface exchange coefficients and a revised
steady-state model incorporating eye dynamics. J. Atmos. Sci., 52
Holland, G., 1996: The maximum potential intensity of tropical cyclones. J. Atmos. Sci.