Seasonal and Interannual Variability in the Barrier Layer of the Bay of Bengal

An objectively analyzed monthly gridded ocean analysis derived from a combination of satellite and in situ observations is used to describe the seasonal and interannual variability in the barrier layer thickness (BLT) over the maximum variance region in the BLT of the Bay of Bengal (BoB) for the period from 1993 to 2012. The northern BoB acquires a maximum variance in the BLT where a large river discharge flux was observed. The BLT showed strong seasonal variability with minima during April-May and maxima during December-February. An investigation of the variability in the BLT showed large amplitude at annual and semiannual time scales. The relationship between the BLT and the Indian Ocean dipole mode (IOD) reveals that the BLT maximum is relatively high in the negative IOD years when compared to the positive IOD years. A significant relation between the BLT and IOD is inferred with the IOD leading the BLT by 3 months and lagging by 1 month. We show that the 1 month lag in the northern BoB is mainly associated with coastally trapped Kelvin waves that radiate Rossby waves and control the BLT. However, further investigation is required regarding the temporal lead of the IOD with the BLT in the northern BoB.