Moored Observations of the Savu Strait Currents in the Indonesian Seas. Issue 7 (14th July 2020)

• Record Type: Journal Article
• Authors: Wang, Jing; Yuan, Dongliang; Li, Xiang; Li, Yao; Wang, Zheng; Hu, Xiaoyue; Zhao, Xia; Corvianawatie, Corry; Surinati, Dewi
• Is Part Of: Journal of geophysical research. Volume 125:Issue 7(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-14
• Subjects: Savu Strait -- Kelvin wave -- Indian Ocean -- ITF; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2020JC016082
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: 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 3 /s), 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. Plain Language Summary: The Savu Strait located between the Savu Sea and Indian Ocean is a direct passage connecting the Indonesian seas and the Indian Ocean, which has been rarely observed so far. The sandwich structure of the Savu Strait current is disclosed by an acoustic Doppler current profilers (ADCPs) and current meters attached to a mooring in the Savu Strait. Based on water mass analysis, water pathways of the whole water column in the regions surrounding the Savu Sea are found. The transports through the straits surrounding the Savu Sea are also estimated combining the mooring observation, shipboard ADCP data, and mass conservation. A linear stratified model and high‐resolution regional model are used to simulate the mean state and variability of the currents observed by subsurface mooring. The linear dynamics of the currents in the Savu Strait are studied. It is found that the baroclinic Kelvin waves in the Indian Ocean dominate the mean current variability in the Savu Strait. The baroclinic processes thread a needle to the reverse flow in the Savu Strait. The disclosed results are important for the understanding the ocean circulation of the regions surrounding the Savu Sea. Key Points: Current observations from a subsurface mooring in the Savu Strait feature a sandwich structure in the whole water column A new pathway in the regions surrounding Savu Sea is disclosed from the water mass analysis The northeastward current in the Savu Strait in the middle layer is primarily forced by baroclinic Kevin wave in the Indian Ocean