Identification of Thermal Front in Indonesian Waters During 2007 – 2017

Abstract

Indonesia is a region that is directly adjacent to the Pacific Ocean and the Indian Ocean which allows a thermal front phenomenon. The purpose of this study was to identify the presence of thermal fronts based on seasonal variations and inter-annual variations in Indonesia waters. The data used in this study were Sea Surface Temperature (SST), Ocean Nino Index (ONI), and Dipole Mode Index (DMI) from January 2007 - December 2017 (11 years). The SST data was a level 3 Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) satellite image data with a resolution of 4 km. SST data was analysed using remote sensing techniques and Geographic Information System (GIS). The results of this study indicated that the distribution of SST and thermal fronts were influenced by seasonal variations and inter-annual variations. The highest average thermal front event in Indonesian waters occurred in a combination of El-Nino and Positive Indian Ocean Dipole (IOD) conditions. The highest average thermal front incidence in Indonesian waters also occurred during the East Season, while the smallest average occurred during the Transition Season II. During West Season, Transition Season II, and East Season, the largest number of thermal fronts was found in Western Indonesian Waters. Meanwhile, in the Transition Season I, the largest number of thermal fronts was found in Central Indonesian Waters. Thermal fronts were often found when the SST of Indonesian waters were cooler than normal conditions. The cooler condition made the SST more heterogeneous and formulated the thermal front phenomenon.