ENSO and IOD influence on Indonesian Throughflow variability in the Makassar Strait and Banda Sea

The Indonesian Throughflow (ITF) is a critical component of global ocean circulation, yet its response to simultaneous climate phenomena remains complex. This study examines the influence of El Niño- Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on oceanographic anomalies in the Makassar Strait and Banda Sea from 2021 to 2024. Satellite data for sea surface temperature (SST), chlorophyll-a (Chl- a), sea surface salinity (SSS), and surface current velocity (CUR) were analyzed to identify spatial distribution patterns during different climate phases. During La Niña, positive SST anomalies were observed due to strengthened ITF warm water transport and reduced upwelling. Conversely, during El Niño–IOD+ phases, SST anomalies were more localized, and Chl- a concentrations significantly decreased, particularly in the Banda Sea. Statistical analysis revealed that ENSO has a strong negative correlation with Chl-a (r = -0.58) and a strong positive correlation with CUR (r = 0.68) in the Makassar Strait. The findings highlight that ENSO and IOD act as primary drivers of regional oceanographic variability, significantly altering the biological and physical characteristics of the ITF corridors.