Stratification of Indonesian Throughflow Water and Its Circulation along 125E in the Banggai - Maluku Sea

¹ Graduate Magister program in Marine Sciences, Faculty of Fisheries and Marine Sciences, IPB University, 16680, Bogor, Indonesia
² Marine Science and Technology Department, Faculty of Fisheries and Marine Sciences, IPB University, 16680, Bogor, Indonesia
³ Research Center for Oceanography, National Research and Innovation Agency, 10340, Central Jakarta, DKI Jakarta, Indonesia
⁴ Research Center for Climate and Atmosphere, National Research and Innovation Agency, 40173, Bandung, Indonesia
⁵ Marine Science Program, Faculty of Fisheries and Marine Sciences, Pattimura University, 97233, Ambon, Maluku, Indonesia

^* Corresponding author: natih@apps.ipb.ac.id

Abstract

secondary pathway of Indonesian Throughflow (ITF) that enters from its inflow portal of the northern Maluku Sea is assumed to recirculate in the Banggai - Maluku Sea, where its upper-layer circulation returns into the Pacific and deeper flows continue southward into Seram/Banda Sea via Lifamatola Strait. However, direct observation in this key region is still limited. Here, using direct CTD (Conductivity Temperature Depth) casts and shipboard ADCP (Acoustic Doppler Curent Profiler) measurement datasets from BUDEE (Banggai Upwelling Dynamics and Ecosystem Experiment) cruise in September 2023, we study stratification and structure of ITF water and its circulation in a meridional section along 125E. The results show the water mass stratification of the mixed layer having a depth of 0-75m with a temperature range of 26-29°C, while the thermocline layer has a depth of 28-407m with a temperature range of 23-26°C, and the deep layer has a depth of 407-1000m with a temperature value of 4-12°C. The current pattern of the Banggai Sea Maluku Sea at a depth of 52-400m is more dominantly influenced by non-tidal currents, the influence of tidal currents only covers a depth of 52m less than non-tidal currents.