Assessment of coastal altimetry data in the South China Sea using multiple frequency approaches

With a coastline length extending over 13, 000 km, including the Malaysia region, the South China Sea presents a challenge to retrieve high quality data along the coastal area especially the sea level anomaly and significant wave height. Currently, coastal altimetry is still facing some issues especially when using the low frequency data such as data lacking near the coast, questionable data accuracy since the altimeter footprint contaminated with the land and less coverage of data from the installed ground truth data. This study aims to assess the coastal altimetry data of sea level and significant wave height in the South China Sea using low and high frequency approaches. This study involved deriving data from sea level anomaly (SLA) and significant wave height (SWH) through the use of Prototype for Expertise on AltiKa for Coastal, Hydrology and Ice (PEACHI) for high frequency and Radar Altimeter Database System (RADS) for low frequency of altimetry and ground truth station which is from tide gauge and Acoustic Wave and Current Profiler (AWAC). Comparison between altimetry and ground truth data has been made in order to validate the significant agreement between them. The validation of the data is to evaluate both types of frequencies with respect to the coastal distance. Consequently, the high frequency results for coastal results with a root mean square reliable ±0.14 metre level for the sea level anomaly (SLA) and ±0.18 metre level for significant wave height (SWH) are more reliable. PEACHI distance-to-coast data obtained a sufficient standard residual deviation ranging from 0 cm to 2.87 cm compared to RADS altimetry ranging from 0.08 cm to 14.20 cm. The findings of this study indicate that the coastal altimetry data benefit coastal development, coastal defence, monitoring and tourism by various related agencies