Utilization of Satellite-Derived Salinity for Indian Monsoon Studies

Corinne Trott
University of South Carolina
  9 Nov, Noon, in 2155

The Indian monsoon is a complex, nonlinear phenomenon involving atmospheric, oceanic, and land-based interactions. Unfortunately, despite decades of research and the aid of new observational and modeling tools, monsoon forecasting remains insufficient and challenging. Because it does not directly affect air-sea fluxes, salinity is often neglected in climate-related studies, though recent works have shown that regional salinity can play an integral role in ocean-atmosphere interactions in the South Eastern Arabian Sea (SEAS) region. The monsoon onset vortex, which is responsible for the initiation of the summertime heavy rainfall over India, is triggered by strong air-sea fluxes intensified by salinity-induced barrier layer formation in the SEAS region, but the monsoonal rainfall intensity is directly tied to the strength and northward propagation of intraseasonal oscillations (ISOs) with periodicities of 30-90 days (MJO events), 10-20 days (quasi-biweekly oscillation) and 3-7 days (synoptic events). Evaluation of coupled models such as the Climate Forecast System (CFS) version 2.0 reveals insufficient detection of ISOs when compared with those detected by satellite-derived salinity from Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP). Northward propagation of ISOs seen in SMAP sea surface salinity modulates the post-monsoon (October-November) air-sea interactions in the northern Indian Ocean, which and are a necessary component of determining upper-ocean mixing conditions in the Arabian Sea that then fuel monsoon onset for the next summer monsoon season. The usage of satellite-derived salinity in coupled atmospheric-ocean models will improve model simulations with respect to the influence of salinity on monsoonal processes .