Interpretation of sea level variability over Malaysian seas using multi-mission satellite altimetry data

Abstract

Geographically, West Malaysia is a peninsula surrounded by seas which have their own characteristics and sea water behavior that are influenced by several factors such as the effects of the monsoon season, water circulation, tidal characteristics, El Nino and La Nina phenomena and so on which may affect coastal as well as marine activities. Traditionally, sea level change is observed using tide gauges installed along the Malaysian coastal area. However, the data obtained are 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, altimeter satellites are used as a new alternative which enable sea level data to be obtained from space observations and to monitor sea level changes via the TOPEX, ERS-1, ERS-2, Jason-1, Jason-2, Jason-3, Envisat, Saral, Cyrosat and Sentinel missions which are available since 1993, thus complementing the tidal gauges. This study focused on the variability of sea levels in Malaysian Seas including the magnitude and trend of the sea level, its characteristics due to seasonal monsoon effects including sea cur rent circulation, tidal characteristics, special events such as El Nino and La Nina, the shape and the characteristics of the Malaysian sea, by using multi-mission satellite altimetery. The acquisition and processing of sea level data were performed by using the radar altimeter database system (RADS). The results of this study indicated that Malaysia's sea levels varied by monsoon seasons, whereas the influence of water circulation, El Nino and La Nina effects were significant for semi -enclosed sea areas such as the Celebes Sea. During the Northeast Monsoon, the sea level of the South China Sea area was higher than in the other areas, while during the Southwest Monsoon, the sea level of the Malacca Straits was higher. The phenomena of El Nino and La Nina, the shape and characteristic of Malaysia's seas, tidal characteristics and ocean circulation also contributed to sea level variability. The results of this study 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.