Type 1- L02170391: Collaborative Research: Atmosphere-Ocean Coupling Causing Ice Shelf Melt in Antarctica (ACCIMA)

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The West Antarctic Ice Sheet (WAIS) represents about 10% of the entire Antarctic ice sheet. The WAIS is currently losing mass due to several of its outlet glaciers draining into the Amundsen Sea. The rate of this mass loss, over natural accretion through snowfall, has also been increasing in recent years. One possible reason for this is increased basal melt of the seaward floating ice shelves of the region's terminal glaciers. This can result from a change in either the temperature, or circulation patterns, of the relatively warm Circumpolar Deep Water (CDW) that enters the subglacial zone, providing heat to increase the basal melt rate. Because much of the WAIS bed lies well below sea-level and is therefore theoretically unstable, there is considerable interest in its stability and mobility of the WAIS ice shelves in a warming ocean. Complete disintegration of the WAIS could in principle raise global sea levels by as much as 4.8 m. Understanding the coupling of large scale atmospheric circulation patterns such as the El-Nino Southern Oscillation (ENSO) and the Southern Annular Mode (SAM), changes in ocean temperature and current regimes, along with the complexity of glacial bed physics and importantly the timescales over which these components interact is a challenging modeling and computational task. A team of researchers from Ohio State, Old Dominion University and NYU will develop and couple components of an earth systems model for the Southern Ocean with a regional emphasis on the West Antarctic. The component system models to be coupled include the polar-optimized version of the Weather Research and Forecasting model (Polar WRF) for the atmosphere. The ocean component will be the Regional Ocean Modeling System (ROMS), and the sea ice component will be the Los Alamos sea ice model (CICE). Retrospective decadal simulations will be done to understand recent past variability. Downscaled future projections for Antarctica will be driven by the global National Center for Atmospheric Research (NCAR) Community Climate Model (CCSM or its equivalent), which is also being used for the IPCC 5th Assessment simulations.This proposal is a responsive submission to the CRI-EaSM solicitation with goals to maximize the utility of available observational and model data for impact assessments through scaling activities and to effectively translate model results and associated uncertainties into the scientific basis for well-informed human adaptation to and management decisions for climate change, specifically addressing the risk of significant sea-level rise in the next century.