Observations, Modelling of the Physical Oceanography in and around the Lembeh Strait, North Sulawesi
Abstract
The two field observations are conducted around the Lembeh Strait in September 2015 and 2016 respectively. Evidences indicated that the structure of sea water around the Lembeh Strait is consisted of North Pacific Tropical Water (NPTW), North Pacific Intermediate Water (NPIW), North Pacific Tropical Intermediate Water (NPTIW, only observed in the south) and Antarctic Intermediate Water (AAIW), and there exists some south-north differences in terms of water mass property: In southern Lembeh Strait, sea water with homogeneous thermohaline property is detected at 200-260m where it is between NPTW and NPIW, and is identified to stem from south Pacific Ocean. The distribution of Mixing Layer Pressure (MLP) illustrated the existence of an onshore surface current in northern Lembeh Strait, which delivers amounts of sea water to the coast, and there exists a southward current along Lembeh Strait. It is indicated the shoaling of thermocline and the deepening of NPIW are only observed at northern Lembeh Strait in 2015, and induced by positive wind stress curl covering northern Lembeh Strait. In addition, at 272m, the daily variation of temperature in northern Lembeh Strait contains 10-32 days and 32-64 days oscillate and happens in-phase and out-of-phase variation with corresponding salinity, which is result from the internal variation of water mass stemmed from north Pacific Ocean instead of wind stress curl.
Furthermore, ROMS model is employed to investigate the seasonal evolution features of water transport in the Lembeh Strait. In general, the direction of water flow in the strait is oriented northward with a maximum volume of about 4x10-3 Sv in August. Interestingly, the volume transport will decrease to nearly zero from November to January. Water transport is mainly controlled by seasonally changed monsoon forcing. The large-scale ocean circulation nearby North Sulawesi is weaker during November-January and stronger from July to September. In addition, the source of water bypass the Lembeh Strait in different seasons is diagnosed and testified by tracer-release experiments. It suggestss that most of the water through the narrow channel are emanatedc from the southern off the Strait, not only the surface water, but also the deep water brought by the upwelling and the internal tides.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS41E2054P
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 4522 ENSO;
- OCEANOGRAPHY: PHYSICALDE: 4532 General circulation;
- OCEANOGRAPHY: PHYSICALDE: 4576 Western boundary currents;
- OCEANOGRAPHY: PHYSICAL