Seasonal variation of the Sunda Shelf Throughflow

Abstract

The Sunda Shelf Throughflow (SSTF) is defined as a seasonal reversal shallow current system flowing from the South China Sea to the Indonesian Throughflow (ITF) region via the Natuna and Java Seas. This current system plays an important role on transferring heat and freshwater fluxes into the ITF system and vice versa. This paper aims to investigate seasonal changes of transport volume in three sections within the Sunda Shelf region (namely Natuna, Karimata and Java section). We used the validated daily ocean circulation model outputs from INDESO configuration between 2008 and 2014. It is shown that mean transport volume of the SSTF is relatively small on the order of-0.5Sv toward the ITF region (1Sv=106m3/s) due to a strong seasonal reversal flow of the SSTF forced by the monsoonal winds. However, on seasonal scale this transport volume strengthens drastically to about 2-3Sv (1-2 Sv) during the northwest (southeast) monsoon period, which is in good agreement with previous studies. Transport estimate in Java section is reduced to about-0.1Sv may be due to a leakage of the flow via Sunda Strait and also a strong recirculation of Makassar ITF into Java Sea.