Near-surface and sub-surface oceanic response associated with the evolution of ENSO events

Abstract

The evolution of El Nino and La Nino a events is characterized by significant interannual variations in the winds and surface heat fluxes over the equatorial, sub-tropical and midlatitude Pacific. The present study is aimed at understanding the roles of wind forcing and heat flux variability in affecting the near-surface and sub-surface oceanic response during ENSO events. For this purpose, three sets of numerical simulation experiments were conducted using an ocean general circulation model (OGCM). Each simulation experiment comprises of a 43-year (1958-2000) integration of the OGCM forced by observed windstress and heat fluxes. In the first experiment EXP1, both the wind-stress and heat fluxes were allowed to vary interannually. In the second experiment EXP2, the OGCM was forced with interannually varying wind-stress; but monthly mean climatological heat fluxes. In the third experiment EXP3, the OGCM was forced with monthly climatological wind-stress and interannually varying heat fluxes.