Instability of tropical western pacific warm pool during the boreal winter and211 spring

摘要

A source of instability in the western Pacific warm pool is shown to be due to211u001esea surface elevation variations caused by changes in the zonal sea-surface 211u001etemperature (SST) gradient and the changes in the Pacific Ocean basin length in 211u001erelation to the warm pool latitudinal location. The variation of the sea-surface 211u001eelevation is measured by using the thermocline depth response calculated from a 211u001etwo-layer ocean. The warm pool is shown to be barely at equilibrium during the 211u001eboreal late winter and early spring by comparing the measured thermocline at 211u001e110(degree)W, 0(degree)E with the calculated thermocline depth. Based on this 211u001eanalysis, a failure or reversal of the climatological zonal winds are apparently 211u001enot a necessary precursor for the instability of the warm pool and initiation of 211u001ea warm event. A warm event can be initiated by an increase in the size of the 211u001ewarm pool and/or an increase in zonal SST differences during the boreal/winter 211u001espring. This mechanism could be an alternate mechanism for El-Nino Southern 211u001eOscillation (ENSO) dynamics to that postulated by Bjeknes (1969).