Horizontal Structure of Banda Eddies and The Relationship to Chlorophyll-a During South East Monsoon in Normal and ENSO Period on 2008-2010

Abstract

Banda Sea is part of Indonesia Fisheries Management Area (WPP 714) which famous for Tuna fisheries. In addition to being influenced by Indonesian Through Flow (ITF), the Banda Sea also influenced by eddies. Banda eddies and the relationship to chlorophyll-a were studied by using the output of ocean circulation model produced by INDESO (Infrastructure Development of Space Oceanography) project in Ministry of Marine Affair and Fisheries. Data from 2008 to 2011 during normal phase of South East Monsoon period (June-August 2008), El Nino phase (June-August 2009), and La Nina phase (June-August 2010) were used. The model results showed two clockwise eddies in the northern of Banda Sea and three counterclockwise eddies in the southern of Banda Sea. The clockwise eddies were found at 20 meter depth and induced upwelling in south water of Buru Island, Ambon Island and Lease Island (Haruku, Saparua and Nusalaut Islands). Otherwise, counterclockwise eddies in the southern of Banda Sea (north of Wetar Island and Yamdena Island) generate the downwelling. High vorticity value of the eddy was found in the northern of Wetar Island. The presence of Banda Eddies on South East Monsoon period play an important role to maintain the water mass balance in the Banda Sea. Eddies also have strong influence on nutrient sinking from the surface of water. In addition, the eddies vorticity increased during the La Nina period and lead to low surface chlorophyll-a in the surface of the Banda Sea.