Improving MJO Simulation in AGCM by Coupling SIT One Dimensional Ocean Model

Abstract:

A one-column TKE type ocean mixed layer model SIT (Snow/Ice/Thermocline) has been coupled with three AGCMs for improving MJO simulation. SIT is designed to have very fine layers near surface and is able to capture diurnal warm layer and cool skin. This refined discretization near ocean surface in SIT provides accurate SST simulation and hence gives precise air-sea interaction. By coupling SIT with ECHAM5, CAM5 and HiRAM, the MJO simulation in three AGCMs are significant improved comparing to AGCM driven by prescribed SST. Moreover, AGCMs coupled with ocean model with coarse uppermost layer are not able to improve MJO simulation as significant as AGCMs coupling with SIT. This study suggests that accurately simulating MJO requires a fine vertical resolution near surface that can capture temperature variations in the upper few meters of the ocean.