10:15 AM - 10:30 AM
[ACG38-06] Do salinity anomalies matter for the evolution of the IOD? –Experimental assessments using a regional ocean model-
Keywords:Indian Ocean Dipole, Salinity anomaly, Regional ocean model
Results from these sensitivity experiments show that interannual salinity anomalies associated with the positive IOD tend to suppress the cooling in the eastern equatorial Indian Ocean by about 1.0°C. Through an on-line heat budget analysis of each experiment, it is shown that weakening of the upwelling in the eastern Indian Ocean, which originates from the upward shift of the Equatorial Undercurrent, is the primary cause of the suppressed cooling there. These changes are induced by enhanced stratification in the eastern equatorial Indian Ocean associated with negative (positive) salinity anomalies near the surface (pycnocline). Momentum budget analysis and additional sensitivity experiments using a linear continuously stratified ocean model further support these ideas. Therefore, salinity plays an active role in the evolution of the IOD, rather than being passively influenced by atmospheric anomalies.