Air‐sea interaction over the Atlantic warm pool in the NCEP CFS

Abstract

This study shows that the SST variations in the July–August–September (JAS) peak season of the Atlantic Warm Pool (AWP) are modulated by the air‐sea fluxes. This feature is captured in the correlations between the rainfall and SST, and rainfall and SST tendency in the multi‐decadal integration of the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFS). Likewise, similar correlations are obtained from the NCEP CFS integration when latent heat flux is correlated with SST and SST tendency. However, when the same Atmospheric General Circulation Model as in the NCEP CFS (also called Global Forecast System [GFS]) is forced with observed SST, then the influence of air‐sea fluxes on SST is lost. Further analysis of observed air‐sea fluxes over the AWP region indicates that surface evaporation is weakly influenced by surface winds and air‐sea humidity variations. But in the NCEP CFS and more so in the NCEP GFS, the latent heat flux, contrary to observations, is strongly modulated by the air‐sea humidity variations.