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Subtropical dipole mode in the Southern Hemisphere: A global view
Author(s) -
Wang F.
Publication year - 2010
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 - 10.1029/2010gl042750
Subject(s) - climatology , predictability , southern hemisphere , subtropics , subtropical indian ocean dipole , forcing (mathematics) , indian ocean dipole , sea surface temperature , northern hemisphere , mixed layer , mode (computer interface) , ocean dynamics , environmental science , atmospheric sciences , antarctic oscillation , latent heat , geology , physics , ocean current , meteorology , quantum mechanics , fishery , computer science , biology , operating system
A global wavenumber‐3 dipole SST mode is showed to exist in the Southern Hemisphere subtropical climate variability in austral summer. A positive (negative) phase of the mode is characterized by cool (warm) SST anomalies in the east and warm (cool) SST anomalies in the southwest of the south Indian, Pacific, and Atlantic Oceans, respectively. This coherent dipole structure is largely a response of ocean mixed layer to the atmospheric forcing characterized by migration and modulation of the subtropical high‐pressures, in which the latent heat flux play a leading role through wind‐induced evaporation, although ocean dynamics may also be crucial in forming SST anomalies attached to the continents. Exploratory analyses suggest that this mode is strongly damped by the negative heat flux feedback, with a persistence time about three months and no spectral peak at interannual to decadal time scales. As the subtropical dipole mode is linearly independent of ENSO and SAM, whether it represents an additional source of climate predictability should be further studied.