Marine Heatwave Characteristics in the Makassar Strait and Its Surrounding Waters

Abstract

This study aimed to investigate the characteristics of marine heatwaves (MHWs) in the Makassar Strait and adjacent waters (MSAW) using the Optimum Interpolation Sea Surface Temperature (OISSTv2) dataset from 1982 to 2021. The analysis revealed a significant positive trend in the frequency and duration of MHWs, while the mean and maximum intensities displayed a negative trend over the 40-year period. By examining two different phases of the Pacific Decadal Oscillation (PDO), it was observed that the cold phase (more frequent La Niña events than El Niño) had higher MHW frequency and duration, whereas the warm phase (more frequent El Niño events than La Niña) exhibited higher mean and maximum intensities. Moreover, the occurrence of high-intensity MHWs was associated with weakened winds, the decaying phase of El Niño and positive Indian Ocean Dipole (IOD), and high net surface heat flux (NSHF). An intriguing finding emerged, indicating a notable lag of 7–9 months (10 months) between El Niño (positive IOD) events and the emergence of high-intensity MHWs. This lag suggests that MHWs are more likely to manifest during the transition towards La Niña and negative IOD conditions. Additionally, the study highlighted a stronger correlation between the El Niño–Southern Oscillation and MHW intensity in the MSAW compared to the IOD. Furthermore, the different intensities of MHWs were found to be linked to NSHF, which exhibited higher values during the warm phase of the PDO compared to the cold phase.