Abstract
The East India Coastal Current (EICC), the Western Boundary Current (WBC) in the Bay of Bengal (BOB) is continuous northward and southward during pre- and post-Indian Summer Monsoon (ISM), respectively. The discontinuity in EICC occurs during ISM (June–September) when the boundary current remains inconsistent with various cyclonic and anticyclonic eddies in presence of a southward flow from 21°N and a northward flow from 10°N along the boundary. The variations in this summertime EICC discontinuity during the contrasting Indian Ocean Dipole (IOD) events of 2008 (positive) and 2010 (negative) are investigated here. The study uses a 1/12° Regional Ocean Modelling System (ROMS) simulation, available observations and reanalysis data. The study reveals that the strong coastal Kelvin and reflected Rossby waves during 2010, supported by strong winds in the equatorial Indian Ocean, helped to strengthen the spring and winter time continuous EICC. The continuous EICC remained very weak with the weaker equatorial remote forcing signals in 2008. The southward and northward flows from 21°N and 10°N, respectively were much stronger during 2010 ISM. However, strong eddy activities along the boundary reduced these two flows in 2008. The year 2010 showed relatively weak, but well-distributed eddy activity over the whole western BOB during ISM. Conversely, pronounced eddy activity near the western boundary with high eddy kinetic energy accumulation increases the inconsistency in boundary current flow during ISM of 2008. Therefore, the study suggests that the contrasting IOD modes have significant and complementary influence on WBC discontinuity in the BOB.
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