Indian Ocean surface circulations and their connection to Indian Ocean dipole, identified from Ocean Surface Currents Analysis Real Time (OSCAR) data

摘要

Ocean surface circulation is an essential component of the world climate system. In this study, the Ocean Surface Currents Analysis - Real Time (OSCAR) data, derived from satellite altimeter and scatterometer, is used to investigate the connection between the Indian Ocean Dipole and eastward equatorial jet. The raw OSCAR data set was refined using the Optimal Spectral Decomposition method (OSD). Data was analyzed to show the seasonal variability of the surface currents in the Indian Ocean with emphasis on the Somali current, North Arabian Sea, and Bay of Bengal. To investigate the link between the Eastward Equatorial jets (Wyrtki jets) and the Indian Ocean Dipole (IOD) Mode events, complex EOF analysis was applied to the currents in the Equatorial region. This analysis revealed that the spatial anomaly of the currents along the equator can directly relate to the occurrence of a Dipole Mode event. Further zonal currents anomalies and vector plots, for the years with Dipole Mode events, also depicted the anomalous behavior of the equatorial jets during a Dipole Mode event. This study demonstrates that satellite-based altimetry data can be used to refine the climatological knowledge of a certain region in the world.