Tidal Circulation in the Hooghly Estuary and Adjacent Coastal Oceans.

A terrain-following ocean general circulation model is implemented for simulating tidal and residual circulation patterns in the Hooghly Estuary and its adjacent coastal oceans (HECO) on the east coast of India. The model is forced with time-varying tidal levels and momentum fluxes at the eastern and southern open boundaries, and winds at the air–sea interface. Simulated tidal levels and currents are compared well with the observations. Based on model solutions, spatial patterns of semi-diurnal and diurnal tides and circulation are described. The residual circulation shows prevalence of ocean-ward along channel flow from north to south with distinct differential circulation patterns on its right and left flanks of the outer estuary. A mesoscale eddy associated with residual circulation has been occurring in the southwestern flank of the HECO, adjacent to the Digha coast. This is associated with enriched chlorophyll_a concentration (Chla), causing the region as the suitable place for the fishing activity. The residual currents in the left of the channel (toward the Sunderban) in the southeastern flank of the HECO are eastward and diverging in nature and are associated with reduced Chla. [ABSTRACT FROM AUTHOR]