Summary of Abstract Submission

Abstract Submission No. IO50-02-0003PresentationOral

THE LONG MARCH FROM IIOE TO IIOE-2: EVOLUTION OF OUR THEORETICAL UNDERSTANDING OF THE DYNAMICS OF THE NORTH INDIAN OCEAN

D. Shankar*1

1 CSIR-National Institute of Oceanography, Dona Paula, Goa 403004., India

ABSTRACT :

The International Indian Ocean Expedition marked the beginning of our study of the seasonally reversing circulation of the north Indian Ocean. The data collected during this expedition and in subsequent decades led eventually to a theoretical framework, primarily involving long baroclinic waves, that we use today to describe and understand the observed circulation. I will show how the theory has evolved, marking significant developments in both observational and modelling studies. To ensure a focus on the theoretical ideas, I will restrict my talk to the East India Coastal Current (EICC) and the West India Coastal Current (WICC), which represent the western-boundary current of the Bay of Bengal and the eastern-boundary current of the Arabian Sea, respectively. Theoretical studies show that it is not possible to explain the variations in the WICC (EICC) without invoking the winds over the Bay of Bengal (equatorial Indian Ocean). For example, the reason for the WICC flowing into the wind in winter is the alongshore pressure gradient set up by seasonal Kelvin waves that are forced by the winds over the east coast of India and propagate from there to the west coast of India. The development of this theory followed similar developments in the Pacific and Atlantic Oceans in the 1970s and 1980s, respectively, and it is of interest to note these connections as we move on to simulating, in the coming decades, the intraseasonal variability now commonly recorded in direct current measurements or seen in satellite altimetry.