Ocean Heat Content and the Intraseasonal Oscillation

Abstract:

Intraseasonal sea surface temperature anomalies generally cool during the convectively active phase of the intraseasonal oscillation in the Indian Ocean, but the behavior of intraseasonal ocean heat content anomalies is quite different. This is demonstrated using satellite observations and ocean reanalysis data. Ocean heat content anomalies generally increase during the convectively active phase of the intraseasonal oscillation and decrease during the convectively suppressed phase. Much of the intraseasonal variability of ocean heat content is westward propagating, moving in the opposite direction of the intraseasonal oscillation's convective envelope. While sea surface temperature anomalies are strongly regulated by variations in surface fluxes, their out of phase relationship with ocean heat content suggests that different processes are modulating the reservoir of warm water in the upper ocean. We hypothesize that oceanic equatorial waves are the primary forcing of intraseasonal ocean heat content anomalies during intraseasonal oscillation events. Evidence is shown that these oceanic waves are synchronous with the intraseasonal oscillation and support the intensification of intraseasonal convection in the central Indian Ocean.