Exploring the genesis and climatic drivers of marine heatwaves in the Indonesian Maritime Continent: Insights from South Java and Karimata Strait

Marine heatwaves (MHWs) are extreme ocean warming events with significant ecological and climatic impacts. While extensively studied in various oceanic regions, the characteristics and underlying mechanisms of MHWs in the Indonesian Maritime Continent (IMC) remain poorly understood. This study investigates the statistics and drivers of MHWs in two key regions of the IMC, South Java and the Karimata Strait, during the period 1982–2021, in conjunction with climatic modes. In both regions low-intensity MHWs occurred regularly as a baseline independent of any climate events, whereas intense and prolonged events were strongly associated with active climate modes. In South Java prolonged and intense MHWs occurred most frequently during the negative phase of the Indian Ocean Dipole mainly by reduced latent heat loss due to weakened wind speeds. The second most frequent but low-intensity MHWs occurred independently of any climate events. In the Karimata Strait, intense and frequent MHWs were closely related with El Niño events, driven by increased shortwave radiation and, secondarily, by reduced latent heat loss. Our findings provide critical insights into the physical mechanisms driving MHWs onset in the IMC, particularly the role of air-sea coupling and ocean dynamics, which are useful for understanding future warming risks.