The Climate Impacts of the Southern Hemisphere Annular Mode

Columbia University, New York NY

Investigators

Abstract

The work will examine the climate dynamics of the Southern Hemisphere Annular Mode (SH AM). Previous results based on an analysis of a coarse resolution coupled ocean-atmosphere model integration have shown that the SH AM has a significant impact on ocean circulation, sea ice thickness, and the total area coverage of ice during winter. As a follow up on their previous work, the PIs will: (i) examine the simulated climate dynamics of the SH AM in non-winter seasons. Since the SH AM weakens only slightly during spring, summer and fall, it is expected that its effect on ocean circulation and sea ice will be similar; and (ii) analyze in detail, the simulated interaction between sea ice and the atmospheric circulation. While the SH AM has a large impact on simulated sea ice variability, evidence suggests that sea ice variations may also affect the atmospheric circulation. The work is important because given recent evidence by Thompson et al. of a trend in the SH AM, results of the research could have important consequences for the global warming debate. A better understanding of how the circumpolar ocean responds to AM-induced changes in the surface westerlies could also be important for understanding changes in ocean biology, the carbon cycle, water mass formation.