The evolution of an extreme positive Indian Ocean Dipole (pIOD) that took place in the tropical Indian Ocean during the late boreal summer to early winter of 2019 is examined in terms of coupled ocean–atmosphere dynamics. The patterns of anomalous sea-surface temperature (SST) revealed a typical pIOD characteristic: cooling (warming) in the southeastern (western) tropical Indian Ocean. Based on the Dipole Mode Index (DMI), the evolution of the event started in mid-July and gradually strengthened with an abrupt weakening in early September before coming to its peak in late October/early November. It quickly weakened in November, and then it terminated in mid-December. During the peak phase of the event, the SST anomaly in the southeastern (western) tropical Indian Ocean reached about −2 °C (+1 °C). The pattern of anomalous SST was followed by an anomalous pattern in precipitation, in which deficit precipitation was observed over the eastern Indian Ocean, particularly over the Indonesia region. Earlier study has shown that dry conditions associated with the pIOD event created a favorable condition for a forest-peat fire in southern Sumatra. The number of fire hotspots has increased significantly during the peak phase of the 2019 pIOD event. In addition, anomalously strong upwelling forced by strong southeasterly wind anomalies along the southern coast of Java and Sumatra had induced a surface chlorophyll-a (Chl-a) bloom in this region. High surface Chl-a concentration was collocated with the negative SST anomalies observed off the southwest Sumatra coast and south Java.

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.

Selat Makassar merupakan lintasan utama dari Arus Lintas Indonesia (ARLINDO). Letak geografis ini menyebabkan Selat Makassar memiliki variabilitas upwelling yang tinggi. Tujuan penelitian ini adalah mengkaji variabilitas musiman upwelling secara spasial dan temporal di Selat Makassar berdasarkan indeks upwelling, klorofil-a, nilai Rrs 443 dan 555, SPL (Suhu Permukaan Laut), SSHA (Sea Surface Height Anomalies) dan EMT (Ekman Mass Transport). Data yang digunakan pada penelitian ini adalah klorofil-a dari OC-CCI (Ocean Colour Climate Change Initiative), SPL dari OISST (Optimum Interpolation Sea Surface Temperature), angin dari ASCAT (Advanced Scatterometer), serta SSHA, Rrs 443, dan Rrs 555 dari situs marine Copernicus yang diolah dengan dengan metode komposit menggunakan software IDL (Interactive Data Language) dan NCL (NCAR Command Language). Puncak upwelling terjadi pada bulan Agustus (musim timur) yang ditandai dengan penurunan SPL (26.66 °C) dan SSHA (-2.27cm), EMT (5.27 ), serta peningkatan klorofil-a hingga 0.80 mg/ , dan indeks upwelling yang bernilai positif (0.948 °C). Hasil Rrs 443 dan Rrs 555 yang tergolong rendah mengindikasikan bahwa terdapat kelimpahan fitoplankton pada Selat Makassar. Musim timur (JJA) EOF1 dan PC1 sebesar 40.0 % serta EOF2 dan PC2 sebesar 10.9%. Hasil EOF1 memiliki pola yang mirip dengan peta spasial klimatologi klorofil-a. Hal tersebut dipengaruhi oleh faktor fisik seperti angin. Nilai anomali positif maupun negatif dipengaruhi fenomena iklim seperti El Nino dan La Nina yang terjadi pada tiap tahunnya. Pada hasil EOF juga didapatkan variabilitas tinggi pada daerah di sekitar 4 – 6 LS. The Makassar Strait is the main route of the Indonesian Cross Flow (ARLINDO). This geographical location causes the Makassar Strait to have high upwelling variability. The aim of this research is to examine the seasonal variability of upwelling spatially and temporally in the Makassar Strait based on the upwelling index, chlorophyll-a, Rrs 443 and 555 values, SST (Sea Surface Temprature), SSHA (Sea Surface Height Anomalies) and EMT (Ekman Mass Transport). The data used in this research are chlorophyll-a from OC-CCI (Ocean Colour Climate Change Initiative), SST from OISST (Optimum Interpolation Sea Surface Temperature), wind from ASCAT (Advanced Scatterometer), and SSHA, Rrs 443, and Rrs 555 from the Copernicus marine site which were processed using the composite method using IDL (Interactive Data Language) and NCL (NCAR Command Language) software. The peak of upwelling occurred in August (eastern season) which was marked by a decrease in SST (26.66 °C) and SSHA (-2.27cm), EMT (5.27 ), as well as an increase in chlorophyll-a up to 0.80 mg/ , and the upwelling index is positive (0.948 °C). The results of Rrs 443 and Rrs 555 which are relatively low indicate that there is an abundance of phytoplankton in the Makassar Strait. East monsoon (JJA) EOF1 and PC1 is 40.0% and EOF2 and PC2 is 10.9%. The EOF1 results have a similar pattern to the spatial map of chlorophyll-a climatology. This is influenced by physical factors such as wind. Positive and negative anomaly values are influenced by climate phenomena such as El Nino and La Nina which occur every year. The EOF results also show high variability in the area around 4° – 6° South Latitude.