Variability of Coastal Upwelling and Its Correlation with El Niño Southern Oscillation (ENSO) in the Maluku Sea

Abstract

Upwelling has important value for marine ecosystems and fisheries businesses because it can increase marine primary productivity and capture fisheries productivity. The objective of this research was to analyze the spatial and temporal variability of coastal upwelling in the Maluku Sea and its relationship to the El Niño Southern Oscillation (ENSO) during 2010-2020 periods. The research location was in the Maluku Sea at coordinates 123⁰ W - 128⁰ E and 2.5⁰ N to -2⁰ S. Upwelling events were analyzed using the seasonal upwelling index, wind variability, sea surface temperature, and chlorophyll-a concentration. The influence of ENSO on upwelling events was analyzed spatially and temporally during the El Nino events (2015 – 2016) and La Nina events (2010 – 2011). The results of the analysis showed that coastal upwelling in the Maluku Sea occured once a year so it was categorized as a periodic upwelling type. Coastal upwelling in the Maluku Sea took place during the Australian monsoon (June, July and August or JJA). The highest upwelling intensity with >15 m³/s/100 m coastline was observed in the Bacan - Obi - Sanana waters, Banggai - Taliabu waters, and Bitung waters. ENSO events modulated the intensity of coastal upwelling in the waters of the Maluku Sea; where La Nina decreased coastal upwelling intensity marked by an increase in sea surface temperature and a decreasing chlorophyll-a concentrations, whereas El Nino increased coastal upwelling intensity marked by a decrease in sea ​​surface temperatures and increasing chlorophyll-a concentrations.