Modulation of the Ganges-Brahmaputra River Plume by the Indian Ocean Dipole and Eddies Inferred from Satellite Observations
[12-Feb-2018] Fournier, S., Vialard, J., Lengaigne, M., Lee, T., Gierach, M.M., and Chaitanya, A.V.S.
Presented at the 2018 Ocean Sciences Meeting
The Bay of Bengal receives large amounts of freshwater from the Ganga-Brahmaputra river during the summer monsoon. The resulting upper-ocean freshening influences seasonal rainfall, cyclones, and biological productivity. Sparse in situ observations suggest that the East India Coastal Current (EICC) transports these freshwaters southward after the monsoon as an approximately 200-km wide, 2000-km long 'river in the sea' along the East Indian coast. Sea surface salinity (SSS) from the Soil Moisture Active Passive (SMAP) satellite provides unprecedented views of this peculiar feature from intraseasonal to interannual timescales. SMAP SSS agree well with in situ measurements, capturing the strong cross-shore SSS contrasts (~10-pss) measured along ship transects. Remote forcing associated with the negative Indian Ocean Dipole in the fall of 2016 caused a stronger EICC and 'river in the sea' that extended by approximately 800 km further south than that in 2015. Mesoscale eddies induced meandering in the EICC that helped exporting the freshwater plume away from the coast.