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The purpose of the COSIM project is to develop, test and apply ocean and ice models in support of DOE Climate Change Research and the Long Term Measure of delivering improved climate data and models needed to determine acceptable levels of greenhouse gases in the atmosphere.
COSIM's mission focus for the next several years is to develop advanced ocean and ice models for evaluating the role of ocean and ice in high-latitude climate change and projecting the impacts of high-latitude change on regions throughout the globe. We will use specific
research areas to guide our model development activities.
Climate change at high latitudes is observed to be rapid and dramatic, with subsequent impacts felt globally. We will be focusing our efforts on three aspects of high latitude change:
- Sea Level Rise: Future sea level rise is caused by thermal expansion of the ocean and by melting of land ice. The rate of sea level rise is one of the largest unknowns in current climate models. The large uncertainties are associated primarily with potentially rapid responses of the Greenland and Antarctic ice sheets to climate change. Melting of these ice sheets can result in significant sea level rise (6m from Greenland, 6m from the West Antarctic Ice Sheet). This effort will therefore be primarily focused on improved modeling of ice sheet dynamics and ice shelf/ocean interactions. In addition, we will develop ocean models with improved estimates of thermal expansion.
- Stability of the Ocean Thermohaline Circulation: A second area of uncertainty is the impact of high-latitude changes on the stability of the ocean thermohaline circulation. The thermohaline circulation is the global overturning circulation that transports heat, salt and other material around the globe. It is driven in large part by the formation of dense salty water in the N. Atlantic and around Antarctica. There is both observational and modeling evidence that a very large influx of fresh water into these regions can weaken or shut down this important circulation. However, we have an inadequate understanding of the thresholds of stability and how high-latitude fresh water inputs impact the strength and stability of the ocean circulation in realistic climate simulations. Our second focus area will address this issue using new modeling techniques and a more fundamental framework for identifying stable and unstable states and transition thresholds.
- Ocean and ice biogeochemistry at high latitudes: A final focus area for COSIM will be modeling ocean and ice biogeochemistry at high latitudes. Unique ecosystems reside along the ice edge and will respond to changes in sea ice extent, impacting carbon and sulfur uptake and exchange. Ecosystems in the ice also play a role in accelerating ice melt. If methane clathrates are released from shallow Arctic sediment deposits, biogeochemical processing will determine how much methane reaches the ocean surface and how much is converted to carbon dioxide. All of these processes will be important as climate models move toward inclusion of biogeochemical feedbacks over the next several years.
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Over the past 15 years, Los Alamos has developed a strong program in numerical modeling of the oceans and sea ice, with special emphasis on high-performance computing. We continue to develop the necessary models and software tools for addressing the important science areas above. In particular, we:
- Develop, validate and optimize the
Parallel Ocean Program (POP), including
improvements in the formulation of the model equations, parameterizations of
physical processes, numerical methods, and portability and performance
optimization on a range of computer architectures.
- Develop, validate and optimize the
Community Ice CodE (CICE), including the
efficient and accurate solution of the ice dynamics equations, improvements in
the sea ice thermodynamics and thickness distribution and implementation of new
or improved parameterizations.
- Develop ice sheet models, with a focus on improved numerical
methods and coupled climate applications.
- Are developing a next-generation hybrid-coordinate version of POP
(HYPOP) and are evaluating hybrid vertical
coordinate approaches against other alternative approaches.
- Add biogeochemical processes to ocean models,
focusing on trace gases like dimethyl sulfide (DMS)
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COSIM started under the Department of Energy's Computer Hardware, Advanced
Mathematics and Model Physics (CHAMMP) program in 1991 with Bob Malone, Rick
Smith and John Dukowicz. Bob Malone has written a nice document detailing the early history of the COSIM effort. You can read his document
here.
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