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A comprehensive investigation was conducted to examine the variations in Chlorophyll-a (Chl-a) levels in the waters located to the south of Java Island throughout the past quarter-century. This study employs satellite data and reanalysis data gathered from multiple sources spanning the period between September 1997 and December 2022. The application of EOF analysis revealed that the most notable elevation in Chl-a contents took place during the seasons of SON (September, October, November) and DJF (December, January, February) in the years 1997/1998 and 2006/2007. It has been determined that this significant increase in Chl-a content in southern Java is contingent upon the fulfillment of a number of circumstances. These conditions are associated with climatic patterns in the Indian Ocean and Pacific Ocean. An elevation in Chl-a content was seen throughout the months of SON and DJF in instances where the Indian Ocean Dipole (IOD) had a positive phase. The concurrent occurrence of a powerful positive IOD and El Niño event in the Pacific Ocean is highly probable to result in a substantial elevation in Chl-a content in the southern region of Java. In addition, our findings indicate that the phenomenon of Kelvin wave upwelling significantly contributes to the elevation of Chl-a levels during the months of June, July, August (JJA), and SON. [ABSTRACT FROM AUTHOR]

The southern coast of South Sulawesi-Indonesia is known as an upwelling area occurring during dry season, which peaks in August. This upwelling area is indicated by high chlorophyll-a (Chl-a) concentrations due to a strong easterly wind-induced upwelling. However, the investigation of Chl-a variability is less studied along the western coast of South Sulawesi. By taking advantages of remote sensing data of Chl-a, sea surface temperature, surface wind, and precipitation, the present study firstly shows that along the western coast of South Sulawesi, there are two areas, which have high primary productivity occurring during the rainy season. The first area is at 119.0° E–119.5° E; 3.5° S–4.0° S, while the second area is at 119.0° E–119.5° E; 3.5° S–4.0° S. The maximum primary productivity in the first (second) area occurs in April (January). The generating mechanism of the high primary productivity along the western coast of South Sulawesi is different from its southern coast. The presence of river runoff in these two areas may bring anthropogenic organic compounds during the peak of rainy season, resulting in increased Chl-a concentration. [ABSTRACT FROM AUTHOR]