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The seas along the Northern Coast of Papua constitute a region with complex oceanographic conditions as they are situated within the Indo-Pacific warm pool (IPWP). The geographical location in the southern hemisphere induces upwelling during the west monsoon season (December-January-February). Additionally, interannual phenomena such as the El Niño Southern Oscillation (ENSO) can impact the intensity of upwelling in these waters. This study aimed to compare the upwelling intensity in the seas along the Northern Coast of Papua during neutral phases and ENSO phases. The main indicators of upwelling are sea surface temperature (SST) and Ekman mass transport (EMT). The data utilized in this study include SST from GHRSST and surface wind from ASCAT. The data processing employed the monthly composite method with spatiotemporal analysis based on anomaly results derived from monthly climatology. The analysis results reveal that El Niño 2015-2016 led to an increase in upwelling intensity ranging from 1.82 to 4.00 m/s², while La Niña 2010-2011 resulted in a weakening of upwelling intensity ranging from 4.95 to 6.56 m/s² in the seas along the Northern Coast of Papua. On the basis of correlation and regression analysis, it can be concluded that offshore EMT significantly influences upwelling anomalies in the southeastern waters, whereas the northwestern waters are more influenced by the shifting IPWP during ENSO. [ABSTRACT FROM AUTHOR]

Indonesia as a region located in the tropics gets a greater heat distribution than the other hemisphere and has an important role in the phenomenon of atmospheric and ocean interactions in the Indo-Pacific region. The heat exchange between the ocean and the atmosphere affects the dynamics of both. The southern coast of Java is known as the upwelling area which is driven by the variability of Ekman transport and Ekman pumping. The present study aims to investigate the effect of heat flux variability on sea surface temperature variability and chlorophyll-a in surface upwelling areas along the Southern coast of Java which was less observed in the previous study. The study was conducted with a quantitative descriptive approach through climatological spatial and temporal data processing for 10 years from 2007 - 2016. The data used are Shortwave Radiation, Longwave Radiation, Latent Heat Flux, Sensible Heat Flux, Sea Surface Temperature, Chlorophyll-a, Surface Wind, and Mixed Layer Depth. The results show that the Southern coast of Java receives an average heat of 547.8 W/m2 per year. Net Heat Flux fluctuations are dominated by heat intake by Shortwave Radiation and heat release by Latent Heat Flux. Net Heat Flux has a very strong relationship with sea surface temperature with the best correlation of 0.84 and 0.83 at lag+2 and lag+3 months indicating that Net Heat Flux plays an important role in modulating changes in sea surface temperature in the next 2-3 months. A significant increase in chlorophyll-a occurred after the Net Heat Flux was positive or there was ocean heating which caused the shoaling of Mixed Layer Depth, resulting in primary productivity in the east monsoon along with nutrient rich entrainment to the surface by EMT and EPV. [ABSTRACT FROM AUTHOR]

Chlorophyll-a is the predominant phytoplankton pigment responsible for determining primary productivity. In the present study, we used satellite-based data of chlorophyll-a, surface wind, and precipitation from 2003 to 2019 to investigate the variability of chlorophyll-a in the northern Maluku Sea and the Sulu Sill and examine its generating mechanism. We found that the chlorophyll-a bloom in the northern Maluku Sea occurs during the southeast monsoon season, while in the Sulu Sill, the chlorophyll-a concentration is higher than that in the northern Maluku Sea and occurs throughout the year. In the northern Maluku Sea, the chlorophyll-a bloom is generated by coastal upwelling. The maximum southerly wind during the southeast monsoon generates the strongest offshore Ekman Mass Transport (EMT) in the northern Maluku Sea triggering coastal upwelling. However, the power spectra analysis of satellite-derived chlorophyll-a shows strong peaks and amplitudes at both fortnightly (MSf) and monthly (Mm) frequencies, indicating that tidal mixing is an important generating mechanism for chlorophyll-a blooms in the Sulu Sill. Shallow bathymetry in the Sulu Sill may aid tidal mixing in effectively transporting nutrients from the near bottom to the sea surface, increasing chlorophyll-a concentration. • Chlorophyll-a bloom in the northern Maluku Sea (Sulu Sill) occurs during the southeast monsoon season (throughout year). • In the northern Maluku Sea, the chlorophyll-a bloom is generated by coastal upwelling due to strongoffshore Ekman Transport. • In the Sulu Sill, tidal mixing is an important mechanism for chlorophyll-a blooms which has strong MSf and Mm signals. [ABSTRACT FROM AUTHOR]

A rare event known as Fujiwhara effect occurred in the southeastern tropical Indian Ocean when tropical cyclones (TCs) Seroja and Odette were co-existed, interacted each other, and merged into one TC in April 2021. Here, remotely sensed data (surface winds, sea surface temperature, chlorophyll-a concentration, and surface currents) were analyzed to determine the impact of Fujiwhara effect on the ocean biophysical variables in the region. Ekman pumping velocity were computed to determine the upwelling/downwelling process. During the entire development of the TCs to the merging, the TCs induced sea surface temperature (SST) cooling and raising sea surface chlorophyll-a. Ekman pumping and inertial pumping may serve as the primary driving force for the observed negative SST anomaly and positive anomaly in chl-a concentration associated with TCs. This rare event adds the complexity of ocean and climate dynamics of the region as an exit gate of the Indonesian throughflow to the Indian Ocean and may have implications to circulation and climate in the Indian Ocean and beyond. The present research likely represents the first scientific documentation of oceanic responses to a Fujiwhara effect in the region. • TC Odette and TC Seroja merged in the southeastern tropical Indian Ocean. • The Fujiwhara effect influences the ocean biophysical parameters. • The Ekman and inertial pumping partly affect the ocean biophysical parameters. [ABSTRACT FROM AUTHOR]