Spatial and temporal variability of geostrophic currents in the Indo-Australian Basin using gridded ARGO Float data

Abstract

Abstract Geostrophic current variability in the Indo-Australian Basin (IAB) of eastern Indian Ocean is analyzed by using monthly gridded salinity and temperature data sets (between 2004 and 2016), from CTD ARGO Float. Geostrophic current is derived from dynamic height calculation. We applied time-series EOF analysis by decomposing geostrophic zonal component into dominant variability in several major modes. The variability of geostrophic currents from CTD Argo data analysis had differences, both spatial and temporal variability. There were four major modes, accounting for of 50.47% of the sum explained variance. The anomaly that occurred near the southern coast of Java cannot be detected due to the limited spatial coverage of the ARGO Float distribution. The spatial pattern in the first mode was indicated by positive anomaly at 110°E-114°E and 7°S-13°S. Furthermore, negative anomaly showed in the southern part of the study area. Variability oscillated with annual, semi-annual and inter-annual periodicity. In the second mode, there was a negative anomaly at 10°S-16°S, the rest of area were shown as the positive anomaly. Variability oscillated with semi-annual, annual and interannual periodicity. In the third and fourth mode, they showed variability with the semiannual, annual and inter-annual periodicity.