Interannual variability of winter-time barrier layer in the Bay of Bengal and the underlying processes
Date
2026Author
Shanif, C.T.
Dey, S.P.
Srinivas, G.
Narvekar, J.
Kumar, S.P.
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This study reveals the detailed mechanism behind the winter-time barrier layer (BL) formation on an interannual timescale in the eastern and western Bay of Bengal (BoB) from an ocean dynamics perspective. The interannual variability (IAV) of winter-time barrier layer thickness (BLT) over the coastal waveguide and eastern BoB is mostly controlled by the isothermal layer depth (ILD) variation induced by the second downwelling Kelvin and associated Rossby wave activities, respectively, which is highly influenced by the El Ni o-Southern Oscillation and Indian Ocean Dipole events. The influence of the Kelvin waves on the BLT variation reduces over the western BoB due to high mixed layer depth (MLD) variability linked with freshwater distribution and vertical mixing. The composite analysis of years with extreme BLT (positive BLT years) and those with the least BLT (negative BLT years), identified by an empirical orthogonal function analysis of BLT anomalies over the western BoB, reveals contrasting mixing dynamics at the mixed layer (ML) base. During the positive BLT years, an enhanced (reduced) vertical mixing at the mixed layer base over the north (south) of 15 N is noted, which reduces the freshwater export beyond 15 N, resulting in shallow (deep) MLD at the northern (southern) bay. A deeper ILD and a shallower MLD over the north lead to the formation of a thick BL in these years. During the negative BLT years, reduced vertical mixing and anomalous poleward coastal currents bring anomalously high-saline water into the bay, which increases the MLD and decreases the BLT.
URI
https://link.springer.com/article/10.1007/s10236-026-01793-9#citeashttp://drs.nio.res.in/drs/handle/2264/9656
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- Scholarly literature [9297]

