Analysis of turbulent mixing in the Eastern Path of Indonesian Throughflow

Abstract

Several studies confirmed that strong transformation of Indonesian Throughflow (ITF) water appears along the eastern ITF pathway from Maluku to Ceram to Banda Seas. This is, presumably, caused by energetic internal tidal activities that generate turbulent mixing. This study was aimed to analysis the turbulent mixing using Thorpe method from CTD data set acquired during the STOKAS 2015 cruise onboard R.V. Baruna Jaya 7 in the eastern ITF region. The study area was divided into four regions: Sulawesi Sea (SUL), Maluku Sea (MAL), Ceram Sea (CER), and Banda Sea (BAN). Thorpe method provides an approach to quantify the overturn of water mass using Thorpe displacement – validated using Galbraith and Kelley (GK) test – and to calculate the kinetic energy dissipation (ε and vertical diffusivity (Kρ). From diagram T-S, the transformation of ARLINDO waters was identified in the gateway. This is supported by a current pattern in which the ARLINDO water mass recirculated in SUL, then moved southward to MAL. The vertical diffusivity eddy (Kρ) varied in the order of 10−5 to 10−2 m2s−1 and its kinetic energy dissipation (ε) varied in the order 10−11 to 10−5 W/Kg in all regions. This mixing was indicated to be driven by internal tide.