A Schematic Model of Low Temperature and High Salinity Seawaters in Southern Java of the Indian Ocean during ENSO-IOD 2017

Abstract

The semi-peRmanent jAva coasTal Upwelling that is known as RATU, it was named semi-permanent because upwelling does not occur every month of the year in Southern Java has been investigated by several international researchers. However, this study focused on investigating the horizontal distribution of upwelling areas, using the indicator of low temperature (max. ∼26°C) and high salinity (min. 34 PSU) seawater mass, in different depth layers. The datasets were obtained from HYCOM, with the wind daily as well as the monthly ONI, SOI ENSO, and DMI datasets obtained from ECMWF, NOAA, BoM Australia, and Jamstec, respectively. Furthermore, the horizontal propagation of the low temperature and high salinity in 2017 at depths of 0 m, 50 m, 75 m, 125 m, 150 m, and 300 m have been observed and modeled as schematics. According to the results, the probable upwelling area begins from 150/125 meters to 75/50 meters layer depth. In these layers, the horizontal propagation from the east monsoon (July) to the transition monsoon (October) dominantly begins from the east and moves westward. This shows the highest correlation between temperature/salinity and SOI occurred from August to October during La Nina, from a depth of 0 m to 100m. Similarly, for the ONI, low temperature and high salinity also occurred from the Normal phase to the La Nina phase. The correlation between temperature/salinity and IOD shows the probable upwelling season occurred during IOD (+) phase until a 100 m depth because salinity becomes more irregular with increasing ocean depth.