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Subtropical Indian Ocean SST dipole events and southern African rainfall
Author(s) -
Reason C. J. C.
Publication year - 2001
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 - 10.1029/2000gl012735
Subject(s) - subtropical indian ocean dipole , climatology , subtropics , anomaly (physics) , sea surface temperature , indian ocean , atmospheric circulation , convergence zone , subtropical ridge , general circulation model , geology , ocean current , environmental science , oceanography , indian ocean dipole , geography , precipitation , climate change , meteorology , biology , physics , condensed matter physics , fishery
An atmospheric general circulation model (AGCM) is used to examine how the regional atmospheric circulation and rainfall over southern Africa respond to a recently observed dipole in subtropical sea surface temperature (SST) over the South Indian Ocean. Observations suggest that when SST is warm to the south of Madagascar and cool off Western Australia, increased summer rains occur over large areas of southeastern Africa. The model results suggest that this SST pattern leads to increased rainfall via enhanced convergence of moister than average air over the region. Increased evaporation occurs over the warm pole in the South West Indian Ocean and this moist air is advected towards Mozambique and eastern South Africa as a result of the low pressure anomaly generated over this pole which strengthens the onshore flow.