Moored Observations of the Savu Strait Currents in the Indonesian Seas

摘要

The currents in the Savu Strait are observed using a subsurface mooring from November 2016 to September 2017. The mean volume transport of the Savu Strait into the Indian Ocean is estimated to be 3.0 Sv (1 Sv = 10~6 m~3s), with a standard deviation of 14.3 Sv. The vertical profile of the mean currents features a sandwich structure, with southwestward currents into the Indian Ocean in the upper 280 m and lower 700 m and weak northeastward currents in between. The analyses suggest that the currents flow into the Savu Sea from the west (through the Sumba and Savu Straits) and northeast (through the Ombai Strait) between 280 and 700 m, which suggests southward transport toward the Indian Ocean only in the unmeasured Dao Strait based on the conservation of mass inside the Savu Sea. These results underline the importance of circulation in the Savu Sea in the exchange between the Indonesian seas and the Indian Ocean. A linear continuously stratified model and high-resolution regional INDESO model are used to investigate the variability and dynamics of the Savu Strait current. The existence of the northeastward current in the middle layer suggests the important role of baroclinic mode processes. Simulations also suggests that current in the Savu Strait is forced remotely by the zonal winds over the equatorial Indian Ocean, which propagate eastward along the coasts of the Nusa Tenggara island chain as coastal Kelvin waves.