Seasonal variability of thermal fronts in the Southwestern Arafura Sea in El Niño dan La Niña

¹ Magister program in Marine Sciences, Faculty of Fisheries and Marine Sciences, IPB University, 16680, Bogor, Indonesia
² Marine Sciences, Faculty of Fisheries and Marine Sciences, IPB University, 16680, Bogor, Indonesia

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Sea surface temperature (SST) thermal fronts in eastern Indonesian waters are strongly modulated by monsoonal winds and regional interactions. Previous studies have mainly focused on the northern Arafura Sea and the Banda Sea, where strong upwelling and large-scale circulation dominate. In contrast, the southwestern Arafura Sea relatively understudied, despite its shallow continental shelf and strong exposure to seasonal monsoonal winds and ENSO-related climate variability. This study investigated the spatial and temporal variability of SST thermal fronts in the southwestern Arafura Sea under contrasting monsoonal phases and ENSO conditions. OSTIA product used to calculate horizontal SST gradients as indicators of surface thermal fronts, while wind forcing was analyzed using ERA5 reanalysis data. The results indicate that monsoonal circulation exerts the primary control on the intensity and distribution of SST thermal fronts, with ENSO acting as a secondary modulator. During the Southeast Monsoon, stronger southeasterly winds and enhanced surface cooling generate more intense and widespread frontal activity, particularly during La Niña events. In contrast, frontal signatures weaken during the Northwest Monsoon, when wind forcing and upwelling are reduced. These findings highlight the combined influence of seasonal monsoonal forcing and large- scale climate variability on SST thermal front dynamics in the southwestern Arafura Sea.