The Retracked Sea Levels from SARAL/AltiKa Satellite Altimetry: the Case Study around the Strait of Malacca and the South China Sea

Abstract

This paper examines the quality of retracked sea surface heights (SSHs) from SARAL/AltiKa satellite altimetry over the Strait of Malacca and the South China Sea. The SSHs are retrieved from retracked SSHs taken by MLE-4, Ice-1 and Ice-2 retrackers which is provided in the Sensor Geophysical Data Records that has been optimized for coastal oceans. Based on the analysis of data availability, SARAL/AltiKa data coverage is excellent beyond 5 km from the coastline after removing the outliers, which can provide greater than or equal to 82% of data for both regions. However, this value is somewhat lower when they are close to the coast due to the impact of land and coastal sea states to the altimetric signals. The Ice-1 retracker appears superior in providing SSHs data for the regions when compared to those of the Ice-2 and MLE-4 retrackers. In comparison with geoid height, the Improvement of Percentage (IMP) of Ice-1 retracker (35%) is higher when compared to Ice-2 retracker (27%) over the Strait of Malacca. In contrast, over the South China Sea, Ice-2 retracker has higher IMP (43%) than those of Ice-1 retracker (39%). Comparison with tide gauge stations indicates that the retracked SSHs from Ice-1 retracker are more accurate than the other retrackers.