Sea level anomaly assessment of SARAL/AltiKa mission using high and low resolution data

Abstract

Peninsular Malaysia is located at the focal point of Sunda Shelf, encompassed by the South China Sea to the East and by Andaman Sea at Indian Ocean in the west that causes various phenomena relevant to sea level along Malaysian coast. When the monsoons strike, the effect of wind and other factors will change the variability of Sea Level Anomaly (SLA) along coastal Malaysia. Traditionally, sea level change is observed using tide gauge installed along Malaysian coastal area. However, the data obtained is limited to the tide gauge station area, the sea level data for the deep sea cannot be obtained and there is no long-term record of observation. Therefore, satellite altimeter is used as a new alternative which enables sea level data to be obtained from space observation and to monitor SLA via SARAL/AltiKa which available since 2013, thus complementing the tide gauge. The aim of this study is to derive SLA parameter from high and low resolution of satellite altimetry data. This study involved the acquisition of SLA data by using RADS and PEACHI (AVISO) database system from satellite mission SARAL/AltiKa. Sequentially, SLA data has been analysed and evaluated based on tide gauge data provided by using UHSLC system. Comparison between the high resolution (PEACHI) and low resolution (RADS) data has been made to evaluate the density of altimetry data in term of distance to coast. As a result, high resolution (PEACHI) data are more accurate for coastal application with root mean square error (RMSE) of ±0.14 metre level. The analysis shows that the footprint of high resolution altimetry data is denser than the low resolution altimetry data. Data from distance to coast for PEACHI achieved a satisfactory standard deviation of residual, which is ranged between 0 cm to 1.04 cm as compared to altimetry RADS which is ranged 0.34 cm to 12.57 cm. The results can be used by various agencies in planning and developing Malaysian coastal areas as well as in assisting the development of community economies such as fishery and tourism activities.