Determination of the mean dynamic topography over peninsular Malaysian seas using multi-mission satellite altimetry

Abstract

Since the launch of the maiden altimetry satellites, altimetric data has enormously been used to better understand worldwide oceanic system and how it evolves at different temporal and spatial scales. The purpose of this study is to determine the mean dynamic topography (MDT) of the Peninsular Malaysian Seas covering the Malacca Strait and South China Sea using multi-missions satellite altimetry. The radar altimeter database system (RADS) was used to capture and process ENVISAT, CRYOSAT-2, SARAL, JASON-1 & JASON-2 satellite altimeter (SALT) data of five years spanning between 2011-2015. In the RADS processing, the 2016 upgraded geophysical and environmental corrections suitable for the Malaysian Seas were applied. The time series of monthly multi-mission SALT data showed estimated sea level trend of 3.6 mm/year, 1.0 mm/year, 2.4 mm/year, 12 mm/year and 2.4 mm/year at Cendering, Gelang, Port Kelang, Keling and Kukup respectively. The correlation analysis for the selected tide gauge stations produced satisfying results of R2 with 0.968, 0.856, 0.911 and 0.89 for Geting, Cendering, Gelang and Sedili respectively. The ITG-Grace2010s geoid model was used to compute the MDT and plotted to a grid of 0.25° for the Malacca Strait and South China Sea of Peninsular Malaysia with Geting, Johor Bahru, Port Kelang, Keling and Sedili tide gauge stations having values determined by interpolation to be 1.2633m, 2.9109m, 1.1863m, 1.1406m and 1.8818m respectively. From the SALT computed MDT with respect to Port Kelang, the north-south sea slope ranges between -0.64 to 0.29 m/50km and between -0.01 to 0.52 m/50km along the east and west coasts of Peninsular Malaysia respectively. The computed SALT and Tidal MDTs were compared, resulting in centimeter differences at the selected tide gauge benchmarks, except at Johor Bahru having a difference of ~ 1.49m. The plotted grid of the derived MDT showed that the separation of the MSS and the ITGGrace2010s geoid is smoother at the Malacca Straits, while the magnitude is larger and more undulated at the South China Sea. The determined MDT showed the huge potential SALT has in helping to fully map, study and understand the marine topography and environment.