LATENT-HEAT FLUX AND INTERANNUAL VARIABILITY OF THE COUPLED ATMOSPHERE-OCEAN SYSTEM

This study examines the impact of the moisture exchange between the oc eanic and atmospheric boundary layers on instabilities of the atmosphe re-ocean system. Wind speed-sensitive evaporation can affect these ins tabilities in two ways. First, it can change atmospheric heating and t hus modify the atmospheric wind response. Second, it can change the mi xed layer heat budget and thus affect SST. Here the authors show that wind speed-sensitive evaporation produces a new unstable, westward-pro pagating SST mode with a growth rate of (4 month)(-1) for standard par ameters. These two processes, alternatively, act to stabilize the lead ing unstable mixed SST-dynamics mode if each is considered separately. However, the strongest instability of this mixed SST-dynamics mode oc curs when the first process is relatively weak and the second is stron g. The authors extend the work to consider the impact of wind speed-se nsitive evaporation on the intermediate coupled model of Zebiak and Ca ne. The results from this model are similar to those obtained in the f ree mode analysis.