Upwelling index along the South Coast of Java from satellite imagery of wind stress and sea surface temperature

Abstract

Upwelling Index which is processed from satellite imagery of wind stress and Sea Surface Temperature (SST) were examined to describe upwelling and its dynamics along the southern coast of Java. Analysis in September as the peak of upwelling shows that the commonly use of Ekman Transport-based Upwelling Index mostly shows higher values on the western part of south coast of Java as the alongshore wind stress is stronger to the west. But on the contrary, the SST-based Upwelling Index shows a relatively intense and persistent upwelling on the eastern part of south coast of Java and strengthened in El Nino year of 2015. The intense upwelling is indicated by the lowest value of SST minimum and the maximum value of thermal gradient SST up to 75 km off shore. Thus, for upwelling areas that are not predominantly induced by offshore Ekman Transport, the dynamics of upwelling would be better seen through an SST-based upwelling index. The use of both upwelling indices, will complement each other so that upwelling and its dynamics can be precisely understood.