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Summer Research Fellowship Programme of India's Science Academies

Variability of surface and subsurface transport of East India Coastal Current

Ms. D ARDRA

Cochin University of Science and Technology, Kochi, Kerala, 682002                                                     

DR. P A FRANCIS

ESS0-INCOIS, Ocean Valley, Pragathi Nagar, Hyderabad, 500090

Abstract

East India Coastal Current (EICC) is a seasonally reversing western boundary current (WBC) of the Bay of Bengal. In this study, we estimate the volume transport associated with the western boundary current in the southern part (12°N) of the east coast of India using simulations from a very high-resolution (2.23 km) model based on Regional Ocean Modelling System (ROMS). The model simulations are validated using data from Acoustic Doppler Current Profiler deployed on the slope off the east coast of India. The objective of the present study is to estimate the variability of surface and subsurface volume transport of the western boundary currents and to understand the role of undercurrents on the total volume transport in the western boundary of Bay of Bengal. We restrict our analysis to the southern part of the east coast of India, (12oN), where the undercurrents are prominent. Results shows that the volume transport during spring in the surface layers (0-150 m) 5.28 Sv (Poleward), which is consistent with earlier estimates. However, the subsurface (150-3000 m) volume transport of the western boundary currents are entirely differs from surface transport. In spring, subsurface transport is about 7.45 Sv (Equatorward). This opposing transport in the surface and subsurface layers shows that the total transport in this region is entirely different from the previously known pattern. During the winter season also, we could see an undercurrent opposite to surface current. This undercurrent has a prominent role in the volume transport along the east coast of India. Results show that more than 55% of the net transport is contributed by this undercurrent.

Keywords: EICC, ROMS, Western boundary currents.

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