Interannual variability of sea surface height difference between western Pacific Ocean and eastern Indian Ocean and its effect to geostrophic current in Lombok Strait

Abstract

Interannual variability of sea surface height (SSH) in western Pacific Ocean and eastern Indian Ocean occurs as a result of the ENSO phenomena. This variability affects SSH difference between both of those oceans. In normal condition, SSH in western Pacific Ocean is higher than in eastern Indian Ocean which causes a current that passes through Indonesia which known as the Indonesian Throughflow (ITF). This study used SSH and geostrophic currents data from 1993 to 2015 which obtained from AVISO satellite altimetry data to determine the variability of SSH difference in ENSO condition which represented by the sea surface temperature (SST) anomaly of Niño 3.4 data from NOAA and its relation to the geostrophic currents in Lombok Strait which is one of the ITF crossing path. The result of the correlation calculation of ENSO condition to SSH difference between western Pacific Ocean and eastern Indian Ocean shows the negative value. It means that SSH difference at both oceans have opposite condition that when El Nino happened SSH in western Pacific Ocean is lower than the eastern Indian Ocean and when La Niña happened SSH in the western Pacific Ocean is higher than the eastern Indian Ocean. The SSH difference does not affect the direction of geostrophic currents but affects its speed.