Numerical Simulation Of Principal Tidal Constituents In The Indonesia Adjacent Seas

Indonesia is the largest archipelago nation in the world, and the Indonesian seashave the special terrain environment. In particular, the Indonesian Throughflow,which passes through this sea area, is a key link of the Great Conveyor of the globalocean. The tidal system in the Indonesian seas is of great complexity as manifested bya number of amphidromic points in the area and the Gulf of Carpentaria, strong tidalcurrents in the straits, and huge tidal energy from the Pacific and Indian Oceans. Thetides play an important role in the Indonesian sea water mixing and circulation, thusthe study of the tides and tidal currents is of significance in the understanding of theIndonesian seas.Rectangular grids are commonly employed in the previous hydrodynamicnumerical simulations of the Indonesian adjacent seas. In this paper, we use the morepopular finite volume coastal models FVCOM, which adopts unstructured triangularmesh, and is capable of fitting dramatically changing coastlines of islands and strait,and is thus particularly suitable for numerical simulations of the Indonesian seas.The principal tidal constituents M2, S2, K1and O1in the Indonesian adjacent seasare numerically simulated using the FVCOM ocean model in this study. Thecomputational domain covers the area from20°S to20°N in the south-north directionand from90°E to150°E in the west-east direction. The average model resolution is1°/12near small islands in the Indonesian adjacent seas, and1°/5near the mainlandcoasts, and1°/2near the open boundary.We use the Etopo1depths, Etopo5depths, and the depths from the navigationchart, and their combinations to construct5different depth data sets to make numerical experiments. The results from these experiments are compared with theharmonic constants at104crossover points of the TOPEX/Poseidon and79tidalstations from the International Hydrographic Organization, showing that theexperiment using Etopo1in the deep ocean, chart data in the Karimata Strait, NatunaSea and the Java Sea, synthesis Etopo1-Etopo5transition data in the Arafura Sea, andEtopo5data in the Gulf of Carpentaria can produce best results.The model results are compared with observations at TOPEX/Poseidon crossoverpoints and tidal gauge stations, showing satisfactory agreement. Theroot-mean-square (RMS) differences in amplitude and phase-lag between the modelresults and the T/P crossover observations for the M2constituent are6cm and7°respectively; the RMS differences for the S2constituent are3cm and8°respectively;the RMS differences for K1constituent are6cm and10°respectively; and those forthe O1constituent are3cm and10°respectively. Based on the model resultsdistributions of tides, tidal current ellipses, tidal residual currents and tidal energy fluxdensity vectors of M2, S2, K1and O1constituents are presented.