Long-Term Observations of Sea Surface Temperature Variability in the Gulf of Mannar

In this study, we conducted long-term temporal and spatial observations of monthly, interannual, and decadal sea surface temperature (SST) variation in the Gulf of Mannar (GoM) for the period from 1870 to 2018. We obtained climatological data from the Met Office Hadley Centre, UK. The monthly time series revealed that April and August were the warmest and coolest months of the year, respectively. The mean SSTs for April and August were 29.85 +/- 0.44 degrees C and 27.15 +/- 0.49 degrees C, respectively. The mean annual highest and lowest SSTs were observed in 2015 and 1890 with SSTs of 28.93 +/- 0.31 degrees C and 27.45 +/- 0.31 degrees C, respectively, and the annual time series revealed a warming SST trend of 0.004 degrees C. Decadal time series also revealed a warming SST trend of 0.04 degrees C, with the highest and lowest mean decadal SSTs being 28.56 +/- 0.21 degrees C in 2010-2018 and 27.78 +/- 0.25 degrees C in 1890-1889, respectively. Throughout the study period, the spatial distribution of climate trends over decades across the GoM revealed a strong spatial gradient, and the region between 6-8 degrees N and 77-78 degrees E was warmer than all other regions of the GoM.