Seasonal Sea Surface Circulation in the Northwest Region Off the Borneo Island Based on Nineteen Years Satellite Altimetry Data

Abstract

AbstractSeasonal variation of sea surface circulation in the northwest coast of Borneo Island were illustrated using altimetry data provided by six missions of satellite altimetry for the period of nineteen years (1993–2011). The estimated sea level anomaly (SLA) from altimetry data using Radar Altimeter Database System (RADS) is consistent with the tide gauge measurement at Kota Kinabalu and Bintulu. The SLA is combined with the 1992–2002 Mean Dynamic Ocean Topography to determine the absolute dynamic topography. Assuming geostrophic balance, the geostrophic current is estimated from the absolute dynamic topography and mapped for four specific months which represent the monsoon seasons; August (Southwest Monsoon), December (Northeast Monsoon), April (inter-monsoon) and October (inter-monsoon). The pattern of estimated surface current is consistent with the Argos-tracked Drifting Buoy’s track. In general, surface circulation in the central part of the southern region of South China Sea during April, October and December is cyclonic. Along the northwest coast of Borneo Island, the surface current is flowing north eastward during all months except in August, when the current is flowing northward. A few eddies have also been observed from the estimated surface current pattern.KeywordsSea surface circulationMonsoonRADSBorneo IslandSatellite altimetry