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Impacts of increasing anthropogenic aerosols on the atmospheric circulation trends of the Southern Hemisphere: An air‐sea positive feedback
Author(s) -
Cai Wenju,
Cowan Tim
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl031706
Subject(s) - atmospheric circulation , ocean gyre , climatology , northern hemisphere , atmospheric sciences , environmental science , southern hemisphere , middle latitudes , atmosphere (unit) , geology , outflow , ocean current , sea surface temperature , forcing (mathematics) , subtropics , oceanography , meteorology , geography , fishery , biology
A recent model study shows that in response to an increasing aerosol forcing, the Southern Hemisphere (SH) ocean circulation, including the Agulhas outflow, its retroflection, and the entire subtropical gyre circulation intensify and shift polewards. Are these oceanic responses manifested in the SH atmospheric circulation? We demonstrate that as a result of the poleward shift, maximum sea surface temperature (SST) gradients, midlatitude storms and the westerly jet shift southward, intensifying the trend of the southern annular mode (SAM). Because the response of the atmospheric circulation to the underlying oceanic anomalies is equivalent barotropic, a poleward shift and intensification in zonal wind and vertical velocities are generated from the atmosphere‐ocean interface to the middle troposphere. These atmospheric circulation responses, in turn, reinforce the ocean circulation changes. This constitutes an air‐sea positive feedback. Our results illustrate an impact of Northern Hemisphere (NH) aerosols on the SH atmospheric circulation trends through a SH ocean circulation response.