Variation of thermodynamic layers over the South Coastal Java Region (SJCR) and their influences on nutrient abundance

Abstract

The variation of thermodynamic layers over the south coastal Java are important components associated with high potential fishery in this region. In addition, this area influenced by several ocean-atmosphere coupled interactions, such as Ocean Current System and Indonesian Through Flow (ITF) and Monsoon. This study designed to analyze spatial and temporal variations of Mixed Layer Depth (MLD), Isothermal Layer Depth (ILD) and Barrier Layer Thickness (BLT). The data used are salinity, temperature, nitrate and oxygen from CSIRO Atlas of Regional Seas (CARS), surface wind and evaporation from European Centre for Medium-Range Weather Forecasts (ECMWF), and precipitation from Tropical Rainfall Measurement Mission (TRMM). Based on the results, during JJA season (boreal summer) the ILD, MLD and BLT layers over the southern coast of Java are relatively shallower. The thickness of ILD was range from 10 – 30 m, while the thickness of MLD and BLT are about <10 m. Meanwhile, during DJF (boreal winter) and MAM seasons (boreal spring), the thickness of the ILD, MLD and BLT layers are deeper. The nutrient distributions are consistent with thermodynamic layer patterns. The highest concentration of nitrate, phosphate and oxygen tends to occur in the boreal summer season due to the upwelling phenomenon which causes the removal of nutrients in the inner layer toward the surface, whereas the lowest concentration tends to occur in the boreal winter season caused by the downwelling phenomenon.