The influence of freshwater input on the dynamics of the Indonesian Seas

This study aimed to examine the effect of freshwater river discharge on dynamics of the Indonesian Seas using the high-resolution (5 km) SYMPHONIE model. Two simulations were performed considering the river-runoff-input(RRI) and non-river-runoff-input(NRI) during the 2009-2019 period. Daily GloFAS data was utilized as the river flow input and validated against actual river discharge data in Indonesia, showing maximum correlation values of 0.86 in Kalimantan. The validity of the sea surface salinity (SSS) simulated by the model was assessed by comparison with data obtained from the SMOS, SMAP, and CCI satellite products. The results indicated that the RRI simulation better agrees with the observational data, with a highly significant linear correlation coefficient of 0.95. A detailed analysis of RRI simulation and observational data revealed good agreement between the observed and simulated patterns of low SSS and high variability in several river mouths located off the Java Sea, such as the Barito River in Kalimantan, Musi and Sindang rivers in Sumatera. SSS values in the Western-Java-Sea (WJV) and Eastern-Java-Sea (EJV) revealed consistent seasonal variations, with minima observed in DJF and MAM seasons and maxima during SON season in both areas.In terms of ocean dynamics,RRI in WJV revealed shallower Mixed-Layer-Depth and Isothermal-Layer-Depth by 5–10 meters throughout the seasons while in the EJV, significant changes were revealed during the SON and thicker Barrier-Layer-Thickness in both areas during DJF and MAM seasons as compared to NRI. Further analysis of the various mechanisms and factors impacting ITFs will also be presented and discussed.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)