UPWELLING CHARACTERISTICS IN THE SOUTHERN JAVA WATERS DURING STRONG LA NINA 2010 AND SUPER EL NINO 2015

  • Agus S. Atmadipoera Department of Marine Science and Technology, IPB University, Bogor
  • Agitha S. Jasmine Master Program of Maritime Technology, IPB University, Bogor
  • Mulia Purba Department of Marine Science and Technology, IPB University, Bogor
  • Anastasia R.T.D. Kuswardani Center for Research and Development of Marine and Coastal Resources, Ministry of Marine Affairs and Fisheries, Jakarta
Keywords: ENSO event, multi-datasets, seasonal upwelling, South Java waters, upwelling index

Abstract

Seasonal coastal upwelling in the Southern Java waters is considered to be modulated by interannual ocean-atmosphere variability of El Nino Southern Oscillation (ENSO).  This study aims to investigate a contrast in seasonal upwelling characteristics during the La Nina 2010 and El Nino 2015 events, by using multi-datasets from INDESO model output and satellite-derived datasets. Distinct characteristics of seasonal upwelling was clearly seen. In La Nina, surface ocean-atmosphere variables were much lower than that observed in El Nino, except for precipitation rate, sea surface temperature, and sea surface height.  In La Nina, warmer (27-28°C) and a very freshwater (<33.80psu) were predominant in the upper 45m depth, concealing upwelling cooler water at subsurface. In contrast, in the El Nino, a drastic upwelled subsurface water of isotherms of 25-26°C and isohalines of 34.24-34.44psu were outcropped at the sea surface. Temperature-based upwelling index is -2°C and +4°C, demonstrating the ENSO has strongly modulated the upwelling intensity. A strong eastward South Java Coastal Current (SJCC) was found only in La Nina event.  Persistent westward Indonesian Throughflow south of 9.5°S were visible both in different ENSO events.  Estimate of Ekman transport derived from model meridional current was intervened strongly by the presence of the SJCC and the ITF.

Published
2020-04-27