Intraseasonal Surface Salinity Variability and the MJO in a Climate Model Geophysical Research Letters

Due to the sparsity of ocean observations, understanding inconsistencies exist even in qualitative respect about the mechanisms of intraseasonal sea surface salinity (SSS) over the Indo-Pacific basin. In this study, a quantitative diagnostic of salinity/freshwater budgets related to the Madden-Julian oscillation (MJO) was conducted based on model simulations. The model applied is a modified version of the NCEP Climate Forecast System, version 2. The application of a coupled model other than ocean-only models is one of the unique aspects of this study. The model modifications resulted in a more realistic MJO simulation and a better simulation of intraseasonal SSS variability as validated against the Aquarius estimates. The mechanisms of the MJO-related SSS variability are further explored by conducting a salinity budget analysis over the mixed layer. The analysis indicates a strong spatial variation of dominant physical processes controlling the local SSS variability. For example, while the role of surface fluxes dominates in the western Indian basin, oceanic advection plays an important role in the eastern Indian and western Pacific oceans.