Analysis of turbulent mixing in Dewakang Sill, Southern Makassar Strait

Abstract

Dewakang Sill is located in southern Makassar Strait, conveying major path of Indonesian Throughflow (ITF), as a confluence region of different water masses, such as salty Pacific water and fresh Java Sea water. Its depth is about 680 m which blocks the ITF flow below this depth into Flores Sea. This research aimed to estimate turbulent mixing in the Dewakang Sill by applying Thorpe analysis using 24 hours “yoyo” CTD data sets, acquired from MAJAFLOX Cruise in August 2015. The results showed that stratification of water masses is dominated by Pacific water origin. Those are North Pacific Subtropical thermocline and Intermediate water masses. Mean dissipation of turbulent kinetic energy (ϵ) and turbulent vertical diffusivity (Kρ) value in the Dewakang Sill are of O(1.08 × 10−6)Wkg−1, and O(2.84 × 10−4) m2s−1 respectively. High correlation between epsilon and internal waves oscillation suggested that internal tidal waves activities are the major forcing for turbulent mixing in the study area.