Ocean Model Simulation of Southern Indian Ocean Surface Currents

Abstract

The dynamic importance of the Southern Indian Ocean (SIO) lies in the fact that it connects the three major world oceans: the Pacific, Atlantic, and Indian Oceans. Modeling study has been used to understand the circulation pattern of this very important region. Simulation of SIO (10°N–60°S and 30°E–120°E) is performed with z-coordinate Ocean General Circulation Model (OGCM) viz; MOM3.0 and the results have been compared with observed ship drift data. It is found that except near coastal boundaries and in equatorial region, the simulated current reproduce most well known current pattern such as Antarctic Circumpolar Current (ACC), South Equatorial Current (SEC) etc. and bears a resemblance to that of the observed data; however the magnitude of the surface current is weaker in model than the observed data, which may be due to deficiency in the forcing field and boundary condition and problem with observed data. The annual mean wind stress curl computed over the oceanic domain reveals about ACC and its similar importance. The way in which the ocean responds to the windstress and vertically integrated transport using model output is fascinating and rather good.

Keywords:

• Southern Indian Ocean
• z-coordinate Ocean General Circulation Model (OGCM)
• Antarctic circumpolar current
• south equatorial current
• wind stress curl
• vertically integrated volume transport

Acknowledgments

We gratefully acknowledge the help of the Center of Ocean Land Atmosphere Studies (COLA), Calverton, MD, USA, and Scientists Drs. Ben Kirtman and Bohua Huang in running the numerical model experiment and with whom we had many useful discussions. We thank Dr. P.C. Pandey, Ex-Director, NCAOR (the then D.O.D., G. O. I.), Goa, India, and Dr. Renguang Wu of COLA, USA, for their valuable suggestions, and thank to NCAOR, Goa, for financial assistance. The authors would like to thank the anonymous reviewer for fruitful comments in modifying the manuscript. We would like to thank Dr. A. J. Mariano of University of Miami for providing the observed current data for the region 30°E–120°E, 60°S–10°N.