High-resolution climate modeling: The influence of weather and sea ice noise on polar climates

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This project will investigate the influence of weather and sea ice noise on polar climates using a modeling technique that has been applied extensively to study the El Nino Southern Oscillation but never before to high latitudes and never at high resolution. The method, known as an interactive ensemble (IE), applies ensemble averaging to the atmosphere, and, in this project, to sea ice fields before they are exchanged with the ocean and land. The IE approach eliminates the influence of high-frequency atmospheric and sea ice variability on the ocean and land, and isolates the coupled intrinsic variability in the climate system. The integrations will be conducted at very high resolution to better resolve physical processes such as turbulent eddies and their role in the mean climate and climate variability. The IE at high resolution holds great promise as a technique for seasonal to annual forecasts as it eliminates uncertainty owing to unresolved spatial scales and unpredictable weather and sea ice noise. The IE approach will be applied to three fundamental problems. The first is to quantify seasonal to interannual predictability of the Arctic atmosphere and sea ice cover when coupled to an ocean with intrinsic variability alone. The second is to determine how characteristics of high-latitude atmospheric variability, such as the annular modes, are coupled to intrinsic variability in the ocean and land. The third is to investigate how variability in the Atlantic Meridional Overturning Circulation (AMOC) depends on the atmospheric weather and sea ice noise. Broader impacts involve the growing need that society and government have for regional predictions in high northern latitudes. They are especially important in the Arctic, where climate change is already taking place at a fast pace and interannual variability in the sea ice appears to be growing as well.