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Internal and forced modes of variability in the Indian Ocean
Author(s) -
Bracco A.,
Kucharski F.,
Molteni F.,
Hazeleger W.,
Severijns C.
Publication year - 2005
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 - 10.1029/2005gl023154
Subject(s) - thermocline , indian ocean dipole , climatology , throughflow , forcing (mathematics) , ocean general circulation model , subtropical indian ocean dipole , walker circulation , geology , el niño southern oscillation , sea surface temperature , indian ocean , mode (computer interface) , atmosphere (unit) , oceanography , general circulation model , meteorology , geography , climate change , computer science , soil science , operating system
Ocean‐atmosphere variability in the tropical Indian Ocean is investigated using observational data and ensemble experiments with a coupled general circulation model. In one ensemble (IO runs) the ocean‐model domain is limited to the Indian Ocean and observed sea surface temperatures force the atmospheric model elsewhere. In a second ensemble (TPIO) the coupled domain includes the Tropical Pacific. The IO runs display a coupled mode of variability with several characteristics of the Indian Ocean Dipole (IOD), but independent on ENSO (El‐Niño Southern Oscillation). Changes in the Walker circulation induced by ENSO are insufficient to trigger IOD events. In the TPIO runs ENSO variability is correlated with the IOD mode as observed. Oceanic processes are responsible for an essential component of ENSO forcing in the Indian Ocean. The ENSO phase conditions the thermocline depth in the Indonesian Throughflow region and in the southeastern IO. TPIO results are in agreement with SODA reanalysis.