Spatial and temporal variability of sea surface temperature during El-Niño Southern Oscillation and Indian Ocean Dipole in the Strait of Malacca and Andaman Sea

Abstract

This study examined the long-term trends and the impacts of climate variability caused by El-Niño Southern/Oscillation (ENSO) and Indian Ocean Dipole (IOD) by using 33-year Advanced Very High Resolution Radiometer (AVHRR) sea surface temperature (SST). The data were retrieved from year 1982 to 2014, hence enabled the observation of both ENSO and IOD events based on this long-term SST trends in the Strait of Malacca (SoM) and Andaman Sea. The 4-km resolution of satellite-derived SST data had been gathered from the National Oceanic and Atmospheric Administration (NOAA). Geographical location portrayed that the seasonal cycle of SST in the SoM and Andaman Sea was characterised by the Asian Monsoon. The correlations between monthly SST in regions with wind velocity, SST anomaly, and indices (Oceanic Niño Index (ONI) and Dipole Mode Index (DMI)) were analysed based on wavelet coherence (WTC) analysis. The seasonal SST in SoM revealed that the temperature was above normal trend during the southwest monsoon, wherein the region experienced warmer temperature especially during the ENSO period due to seasonal wind velocity. The results demonstrated that in certain years, such as in 1992, ENSO was dominating while in 1994, IOD was influential. During the strong El-Niño event in 1997, ONI did not correlate with SST trends in the SoM, whereas during positive IOD in 1994 revealed that DMI did not correlate with SST trends in both SoM and Andaman Sea. The warming trend seemed to have significantly increased over the past 33 years, as displayed by the continuous increment in temperature throughout the years in the study region.