A Comparative Analysis of the Bay of Bengal Ocean State Using Standalone and Coupled Numerical Models

Abstract

This study evaluates the impact of coupled model in simulating the ocean state conditions of Bay of Bengal by comparing standalone and coupled numerical model simulations. The oceanic model is the Regional Ocean Modelling System (ROMS) and the coupled model comprises of ROMS and Weather Research and Forecast modelling system to simulate the oceanic and atmospheric state of the bay. The coupled model is initialized with atmospheric data from Global Data Assimilation System and oceanic data from Estimating the Circulation and Climate of the Ocean (ECCO). The standalone model is initiated with ECCO data and forced by European Centre for Medium Range Weather Forecasts. The simulations are set with a resolution of 12 km in the ocean and 15 km in the atmosphere for the period 2008–2014, and are compared to reanalysis and measurements. The models are compared for their ability to simulate the sea surface temperature, sea surface salinity, sea level, heat flux, sea level pressure and currents in BOB. With the exchange of atmospheric fluxes and sea surface temperature, the coupled model better captured ocean state representations than the standalone model and, matches well with that of the observations. The simulated temperature shows a warm bias in both simulations at 100–150 m depth. The models are able to simulate the seasonal reversal of boundary currents and associated eddies, and variations in heat fluxes over the ocean. The coupled model provides a better simulation of the ocean state and air–sea interaction which can further be used for climate studies over the bay.