Assimilation of Drifter Data in a Circulation Model of the Indian Ocean

Assimilation of drifter data in a circulation model of the Indian Ocean has been explored in the study. Assimilation has been effected using the approach of nudging. The impact of such assimilation has been quantified by comparing the sea level anomalies simulated in runs with and without assimilation against independent observations derived by satellites. It has been found that the assimilation leads to an overall improvement in the quality of simulation. The surface currents simulated in the two runs have been compared with the observed current at a moored equatorial buoy, and the impact of assimilation has been found to be positive. The improvement in forecast capability has also been judged in a representative example. The degree of improvement in the mentioned examples, although not quite negligible, is not too high because of the paucity of the number of drifters deployed. It has been conjectured that such assimilation, when coupled with assimilation of other surface data derived by satellites, may lead to significant enhancement of the quality of simulation.