Analysis of the November 2023 to March 2024 Marine Heatwave in the Java Sea Using Satellite and Profiling Floats Data

다국어 초록 (Multilingual Abstract)

The impacts of ongoing global warming and climate change are increasingly evident, with marine heatwaves(MHWs)representing one of the most critical oceanic responses. MHWs are becoming a significant threat to marine ecosystems and coastal livelihoods, not only through direct impacts on fisheries but also by altering regional weather patterns and increasing the risk of extreme events. This study investigates the long-term characteristics and driving mechanisms of MHWs in the Java Sea, a shallow sea within the Indonesian archipelago, with a specific case study on the 2023-2024 event. Analysis of 42 years using the Operational Sea Surface Temperature and Ice Analysis (OSTIA) satellite data from 1982 to 2024 revealed 69 MHW events, with a significantly increasing trend in their annual frequency and cumulative days. The major MHW event of November 2023-March 2024 occurred under the combined influence of a strong El Niño and a positive Indian Ocean Dipole (IOD). These large-scale modes suppressed the regional monsoon, resulting in weakened surface winds and a significant net heat flux surplus into the ocean. Concurrently, active Madden Jullian Oscillation (MJO) during the MHW led to the formation of a barrier layer that acted as an efficient subsurface heat trap. Subsurface analysis using profiling float data confirmed that this warming was not a mere surface phenomenon, penetrating to depths of 40-70 meters and being exacerbated by the formation of this heat-trapping barrier layer. These findings highlight the complex interplay of multi-scale climate drivers in generating extreme oceanic events in the Indonesian seas.