Numerical simulation of the observed near-surface East India Coastal Current on the continental slope

Mukherjee, A and Shankar, D and Chatterjee, Abhisek and Vinayachandran, P N (2018) Numerical simulation of the observed near-surface East India Coastal Current on the continental slope. In: CLIMATE DYNAMICS, 50 (11-12). pp. 3949-3980.

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Abstract

We simulate the East India Coastal Current (EICC) using two numerical models (resolution an oceanic general circulation model (OGCM) called Modular Ocean Model and a simpler, linear, continuously stratified (LCS) model, and compare the simulated current with observations from moorings equipped with acoustic Doppler current profilers deployed on the continental slope in the western Bay of Bengal (BoB). We also carry out numerical experiments to analyse the processes. Both models simulate well the annual cycle of the EICC, but the performance degrades for the intra-annual and intraseasonal components. In a model-resolution experiment, both models (run at a coarser resolution of ) simulate well the currents in the equatorial Indian Ocean (EIO), but the performance of the high-resolution LCS model as well as the coarse-resolution OGCM, which is good in the EICC regime, degrades in the eastern and northern BoB. An experiment on forcing mechanisms shows that the annual EICC is largely forced by the local alongshore winds in the western BoB and remote forcing due to Ekman pumping over the BoB, but forcing from the EIO has a strong impact on the intra-annual EICC. At intraseasonal periods, local (equatorial) forcing dominates in the south (north) because the Kelvin wave propagates equatorward in the western BoB. A stratification experiment with the LCS model shows that changing the background stratification from EIO to BoB leads to a stronger surface EICC owing to strong coupling of higher order vertical modes with wind forcing for the BoB profiles. These high-order modes, which lead to energy propagating down into the ocean in the form of beams, are important only for the current and do not contribute significantly to the sea level.

Item Type:	Journal Article
Publication:	CLIMATE DYNAMICS
Publisher:	SPRINGER, 233 SPRING ST, NEW YORK, NY 10013 USA
Additional Information:	Copy right of this article belong to SPRINGER, 233 SPRING ST, NEW YORK, NY 10013 USA
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change
Date Deposited:	26 Jun 2018 14:20
Last Modified:	26 Jun 2018 14:20
URI:	http://eprints.iisc.ac.in/id/eprint/60089

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