Evaluation of mixed layer depth in the northern indian ocean simulated by CMIP5 climate models

Abstract

In this study, we examine the mixed layer depth (MLD) simulated by 19 CMIP5 models in order to find the underlying bias dynamics that might lead to inaccurate climate prediction over the northern Indian Ocean (NIO). The relationship of MLDwith related variables showed that cold surface air temperature bias accompanied by north-easterly winds from the landmass northern of the Arabian Sea plays an important role on the bias development. This cold bias leads to more intense surface cooling over the NAS in winter, indicated by overestimation of wind stress and evaporation, and the underestimation of sea surface temperature, air surface temperature, and net heat flux which are favourable for MLD deepening. Our findings suggest that improvements in atmospheric forcing parameterization of CMIP5 models, especially surface air temperature bias, may have a significant impact to reduce the deep MLD bias over the NAS.