A Change of Seasonality of the Upper Arctic Ocean in Response to Atmospheric and Sea-ice Forcing

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The PI proposes to investigate the change of seasonality of the Arctic Ocean Ekman transport and upwelling/downwelling, and their relationships to key components of the Arctic System. A systematic investigation of the Arctic Ocean upwelling and its change of seasonality is needed in order to understand complex interactions among components of a rapidly changing Arctic System. Upwelling is arguably the single most important dynamical variable in oceanography. It forces oceanic gyres through the Sverdrup balance. Upwelling replenishes nutrients in the surface layer and helps to sustain phytoplankton production. It is a conduit for heat flux from the warm Atlantic Water layer of the Arctic Ocean to the mixed layer, where it influences the sea ice thermodynamics and the atmospheric circulation. Upwelling and Ekman transport affect the surface salinity and thus play roles in the oceanic thermohaline circulation. The most intense upwelling occurs along the Arctic coast, so a change of upwelling seasonality can influence land processes, such as the permafrost in nearshore sediments. Daily Ekman transport and upwelling from 1979 to 2006 have been estimated using satellite and buoy observations. This dataset will be updated, validated and made available to the community in the first year of this project. The PI will quantify the changes in seasonality of the Ekman layer, and examine how they are related to the decline in sea-ice cover and to oscillatory climate modes (such as the Arctic Oscillation). The impacts of the changes in seasonality of upwelling on the chlorophyll concentration, mixed-layer temperature and salinity will be examined.