Dynamics of Eddies in the Southeastern Tropical Indian Ocean

Abstract

A holistic study was done on eddies in the Southeastern Tropical Indian Ocean (SETIO) using the HYbrid Coordinate Ocean Model (HYCOM) for 64 years (from 1950 to 2013). The results from the model were verified against the current and the Sea Surface Height Anomaly (SSHA) from Ocean Surface Current Analyses - Real time (OSCAR) and Archiving, Validation and Interpretation of Satellite Oceanographic Data (AVISO) respectively. The verification showed that the model simulates the condition in the area of study relatively well. We discovered that the local wind was not the only factor that contributed to the formation of eddies in the area. The difference in South Java Current (SJC) flow compared to the Indonesian Throughflow (ITF) and South Equatorial Current (SEC) flow as well as the difference in the relative velocity between the currents in the area led us to suspect that shear velocity may be responsible for the formation of eddies. The results from our model corroborated our prediction about shear velocity. Therefore, we attempted to explain the appearance of eddies in the SETIO based on the concept of shear velocity. By observing and documenting the occurrences of eddies in the area, we found that there are 8 cyclonic and 7 anticyclonic eddies in the SETIO. The distribution and frequency of the appearance of eddies varies, depending on the season.