Local air-sea relationship in observations and model simulations

The present study compares the local simultaneous correlation between rainfall-evaporation and sea surface temperature (SST)-SST tendency among observations, coupled general circulation model (CGCM) simulations, and stand-alone atmospheric general circulation model (AGCM) simulations. The purpose is to demonstrate to what extent the model simulations can reproduce the observed air-sea relationship. While the model-simulated correlation agrees with the observations in the tropical eastern Pacific, large discrepancies are found in the subtropics, midlatitudes, and tropical Indo-western Pacific Ocean regions. In tropical Indo-western Pacific Ocean regions and the midlatitudes where the atmosphere contributes to the observed SST changes, the specified SST simulations produce excessive SST forcing, whereas the CGCM captures the atmospheric feedback on the SST, but with somewhat of an overestimation. In the subtropics, both the AGCM and CGCM produce unrealistic positive rainfall-SST correlations. In the tropical western-central Pacific and the North Indian Ocean, the CGCM-simulated evaporation-SST correlation is opposite to that observed because of an excessive dependence of the sea-air humidity difference on the SST.