Observational bifurcation of Wyrtki Jets and its influence on the salinity balance in the eastern Indian Ocean

Abstract

The eastward-propagation phenomenon from GPS-tracking drifters is characterized by strong Wyrtki Jets (WJs), with a maximum velocity of over 1.3 m s−1. Based on data gathered during a 2014 spring sea cruise in the Indian Ocean, the trajectories show the WJs bifurcate at the equator near the eastern boundary and flow northward and southward in two narrow strong currents. Surface currents reverse and flow westward in the east of the bifurcation longitude. In addition, Aquarius satellite data show the high-salinity water flows eastward from the western Indian Ocean, associated with WJs. Salinity budget analyses in the mixed layer using salinity data from Argo and currents data from OSCAR indicate that the WJs do indeed transport the high-salinity water eastward at the equator, and WJs bifurcation transports high-salinity water away from the equator and suppresses the Bay of Bengal and Java coast from freshening. Therefore, the WJs and WJs bifurcation play an important role in maintaining the salinity balance in the eastern Indian Ocean.