An Updated Estimate of the Indonesian Throughflow Geostrophic Transport: Interannual Variability and Salinity Effect

Abstract

While the pivotal role of the Indonesian Throughflow (ITF) in the global ocean circulation and climate has been widely recognized, accurate estimation of its volume transport based on observational data remains challenging. This work provides an updated estimate of the monthly ITF geostrophic transport (ITFG) in the upper 700 m at the IX1 section between Indonesia and Australia. The ITFG estimate is better constrained by improved data correction and new salinity data products. The mean ITFG of 1993–2018 is 8.2 ± 0.2 Sv, in which contributions of the temperature and salinity components (ITFT and ITFS) are 5.5 ± 0.2 and 2.8 ± 0.1 Sv, respectively. The interannual variability (∼4.4 Sv in standard deviation) is dominated by ITFT, as the result of wind-driven thermocline dynamics, and slightly attenuated in amplitude by ITFS. The strengthening trend of 1.33 Sv decade−1 during 1993–2018 primarily arises from ITFS and secondarily from ITFT.