The Southern Ocean in a Warming World: Winds, Carbon and Heat

University Of Arizona, Tucson AZ

Investigators

Abstract

The Southern Ocean surrounding Antarctica is the primary portal through which the vast volume of the intermediate, deep, and bottom waters of the global ocean interact with the surface and thus the global atmosphere. This region has a profound influence on the Earth's climate, oceanic circulation and ecosystems. Current modeling and observational studies suggest that, despite occupying just over a quarter of the surface ocean area: ? the Southern Ocean accounts for up to half of the annual oceanic uptake of anthropogenic carbon dioxide from the atmosphere ? the Southern Ocean accounts for about 70% ± 30% of the excess heat that is transferred from the atmosphere into the ocean each year; and ? the Southern Ocean winds and buoyancy fluxes are the principal source of energy for driving the large-scale deep meridional overturning circulation throughout the global ocean. There are notable inconsistencies in the simulations of the circulation in this complex and underobserved region in the latest generation of EaSMs (earth systems models). These include the sensitivity of Southern Ocean circulation to changes in anthropogenic CO2 uptake, heat and wind variability. Westerly wind variability in turn has been linked to the state of the polar ozone hole. The project seeks to analyze the output of various IPCC-AR5 ESM runs to identify the strengths and weaknesses of the models in comparison with most recent data sources. Using two GFDL ESMs, four model sensitivity runs will also be conducted, which will seek to quantify the role of westerlies in the uptake of carbon and heat in the Southern Ocean.