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Near‐surface salinity and stratification in the north Bay of Bengal from moored observations
Author(s) -
Sengupta Debasis,
Bharath Raj G. N.,
Ravichandran M.,
Sree Lekha J.,
Papa Fabrice
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl068339
Subject(s) - salinity , bay , oceanography , mooring , stratification (seeds) , geology , eddy , monsoon , temperature salinity diagrams , climatology , mixed layer , pycnocline , environmental science , meteorology , turbulence , geography , seed dormancy , botany , germination , dormancy , biology
A thin layer of fresh water from summer monsoon rain and river runoff in the Bay of Bengal (BoB) has profound influence on air‐sea interaction across the south Asian region, but the mechanisms that sustain the low‐salinity layer are as yet unknown. Using the first long time series of high‐frequency observations from a mooring in the north BoB and satellite salinity data, we show that fresh water from major rivers is transported by large‐scale flow and eddies, and shallow salinity stratification persists from summer through the following winter. The moored observations show frequent 0.2–1.2 psu salinity jumps with time scales of 10 min to days, due to O(1–10) km submesoscale salinity fronts moving past the mooring. In winter, satellite sea surface temperature shows 10 km wide filaments of cool water, in line with moored data. Rapid salinity and temperature changes at the mooring are highly coherent, suggesting slumping of salinity‐dominated fronts. Based on these observations, we propose that submesoscale fronts may be one of the important drivers for the persistent fresh layer in the north BoB.