Satellite Estimates of the Barrier Layer in the Indian Ocean

Monthly barrier layer thickness (BLT) estimates produced from satellite measurements are shown for the Indian Ocean. The recently launched Soil Moisture and Ocean Salinity (SMOS) and Aquarius salinity missions are currently supplying global measurements of sea surface salinity at time scales that where previously unobtainable. As a result a multilinear regression model is developed that relates the BLT to sea surface salinity (SSS), temperature (SST) and height anomalies (SSHA). Each parameter is included in order to incorporate the physical parameters that impact the isothermal layer (ILD) and mixed layer depths (MLD) that result in barrier layer (BL) formation. Four regions are selected in this study to evaluate the model where the BLT is most rigorous, the Southeast Arabian Sea (SEAS), Bay of Bengal (BoB), Eastern Equatorial Indian Ocean (EEIO) and Southern Tropical Indian Ocean (STIO). Different mechanisms are important for sustaining the BLT in each of the selected regions. Model estimations using satellite derived SSS are able to capture the 2012 BLT seasonal cycle well in each of the four regions. Errors are highest in the along coastlines where land contamination skews satellite SSS retrievals. The evolution of the BLT from 2012 to 2013 is discussed as well as the advantages and disadvantages of the current model. Results suggest that salinity measurements obtained from Aquarius and SMOS can be used to track and predict the BLT in the Indian Ocean.