Upwelling Mechanism South of the Aru Islands Abdul Basit(1*), Suliskania Nurfitri(2), Mochamad Furqon Azis Ismail(1), Mutiara Rachmat Putri(2), Bernhard Mayer(3), Thomas Pohlmann(3)
(1) BRIN
(2) ITB
(3) Hamburg University
Abstract
The upwelling mechanism over the continental slope south of the Aru Islands during the southeast monsoon (July 2004) was investigated using the Hamburg Shelf Ocean Model (HAMSOM). The results show that relatively strong southeasterly winds around the shelf drove relatively strong westward surface currents. In the east-west direction, by considering the volume continuity over the slope, the westward currents induce onshore subsurface currents and subsequent upward velocity below the Ekman layer, but the onshore currents and upward velocity were relatively weak. The weak onshore currents are mainly due to inhibition by northwestward geostrophic currents. In contrast, relatively strong upwelling was observed over the continental slope connecting the south of the Aru Islands and the Arafura channel (in the north-south direction). Our simulation results indicate that this strong upwelling was mainly caused by the geostrophic currents flowing northwestward, mainly generated by a horizontal pressure gradient. The gradient was due to complex topography around the west of the Aru Islands. Furthermore, the upwelling around the south of the Aru Islands is revealed by the relatively lower sea surface temperature than the surrounding. In this area, the sea surface salinity was relatively lower than the surrounding due to high river discharge from the Papua Coast.
Keywords: Aru Islands, HAMSOM, Salinity, Southeast monsoon, Temperature, Upwelling
