Sea level trend and variability in the Singapore Strait

Abstract. Sea level in the Singapore Strait (SS) exhibits response to various scale phenomena, from local to global. Longest tide gauge records in SS are analysed to derive local sea level trend and annual, inter-annual and multi-decadal sea level variability, which then are attributed to regional and global phenomena. Annual data gaps are reconstructed using functions correlating sea level variability with ENSO. At annual scale, sea level anomalies in SS are (quasi-periodic) monsoon-driven, of the order of ±20 cm, the highest during northeast monsoon and the lowest during southwest monsoon. Interannual regional sea level drops are associated with El Niño events, while the rises are correlated with La Niña episodes; both variations are in the range of ±5 cm. At multi-decadal scale, annual measured sea levels in SS are varying with global mean sea level, rising at the rate 1.2–1.7 mm yr⁻¹ for 1975–2009, 1.8–2.3 mm yr⁻¹ for 1984–2009 and 1.9–4.6 mm yr⁻¹ for 1993–2009. When SS rates are compared with the global trends (2.0, 2.4 and 2.8 mm yr⁻¹, respectively) derived from tide gauge measurements for the same periods, they are smaller in the earlier era and considerably larger in the recent one. Taking into account the first estimate of land subsidence rate, 1–1.5 mm yr⁻¹ in Singapore, the recent trend of absolute sea level rise in SS follows regional tendency.