Spatial Pattern and Temporal Variability of Sea Level Anomaly and Geostrophic Current in the Eastern Indian Ocean from Satellite Altimetry

The Eastern Indian Ocean has complex dynamic circulation systems affected by monsoonal wind circulation and climate variation. This research aimed to investigate the spatial and temporal variability of the sea level, and the geostrophic currents in the Eastern Indian Ocean using altimeter data. We used daily time series sea level anomaly data from 2004-2016 and applied time-series analysis of EOF. The highest four-modes were adopted. Both sea level anomaly and geostrophic zonal component had the sum of explained variance with 79.68% and 35.65%, respectively. The spatial pattern of the sea level anomaly showed dominant variability spread around the west coast of Sumatra and south coast of Java with positive and negative anomalies, as shown in first and second modes, while the third and the fourth mode did not show substantial spatial variability. The dominant temporal variation revealed semi-annual, annual and inter-annual periodicity. Furthermore, for the geostrophic zonal current, spatial pattern in the first to third modes showed high variability around the west coast of Sumatra and south coast of Java, while in the offshore region they showed positive-negative anomalies. In the fourth mode, the spatial pattern showed low variability. The dominant temporal variation revealed annual, semi-annual and inter-annual periodicity. Based on the spatial and temporal variation of the data, the variability in the study area might be associated with the dynamic of coastally trapped Kelvin wave, upwelling and an interannual anomaly of IOD and ENSO. It was also noticed that some patterns indicated as also noticed that some patterns indicated as dynamic of SJC and SEC signals.