Kyla Drushka (Scripps Institution of Oceanography)
Upper ocean salinity variations have the potential to affect air-sea interaction by modulating stratification. This is particularly relevant in the eastern equatorial Indian Ocean, where salinity controls mixed-layer depth and a barrier layer is found between the base of the mixed layer and the thermocline. This is also the region where intraseasonal surface forcing by the Madden-Julian Oscillation (MJO) is strongest. While the impacts of the MJO on sea surface temperature are generally understood, the impacts on salinity have not been well quantified.
In the present study, we use in situ observations from Argo floats and from two RAMA moorings to characterize intraseasonal variations in salinity and barrier-layer thickness in the eastern equatorial Indian Ocean. We find that precipitation and horizontal advection associated with the MJO drive large, coherent salinity anomalies throughout the upper ocean. However, inter-event variability is large and no systematic MJO variation in the thickness of the barrier layer is seen.