Seasonal and interannual variations in local minimum sea surface temperature and maximum chlorophyll-a around the Savu Sea, Indonesia

Abstract Monsoon winds are the primary drivers of seasonal variability in the Indonesian seas, influencing oceanic conditions, including those in the Savu Sea. Previous studies have documented the upwelling-induced cold sea surface temperature (SST) and high chlorophyll-a concentration along the southern coasts of islands around the Savu Sea during the southeast monsoon; this upwelling occurs due to the favorable wind directions and through Ekman dynamics. However, the local physical and biological features along the southern coasts of islands around the Savu Sea are still unexplored, despite high fishery yield in these regions. This study aims to fill that gap by identifying 3 local minimum SST and maximum chlorophyll-a regions in the southeast monsoon along the southern coasts of islands around the Savu Sea and investigating the seasonal and interannual variability between 2011 and 2020, using satellite observations, atmospheric reanalysis data, and archived temperature and salinity profiles. The results indicate that the wind enhanced by local topography leads to SST minima and chlorophyll-a maxima in these regions. During the southeast monsoon, Ekman horizontal temperature transport is the dominant factor in cooling the SST in these regions, driven by coastal upwelling, while air–sea heat flux contributes the most to the SST rising in October during the transition phase. On an interannual timescale, variations in local minimum SST and maximum chlorophyll-a correspond to positive and negative Indian Ocean Dipole (IOD) events, which are driven by sea level anomalies associated with remote forcing from the Indian Ocean.