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Currents and transports of the Monsoon Current south of Sri Lanka
Schott, F.; Reppin, J.; Fischer, J.; Quadfasel, D. (1994). Currents and transports of the Monsoon Current south of Sri Lanka. J. Geophys. Res. 99(C12): 127-141.
In: Journal of Geophysical Research. American Geophysical Union: Richmond. ISSN 0148-0227, more
Peer reviewed article  

Available in  Authors 

    Atmospheric circulation; Current meter moorings; Current profiles; Doppler; Doppler sonar; Drift currents; Extrapolation; Monsoons; Numerical models; Ocean basins; Ocean circulation; Ocean currents; Ocean-atmosphere system; Oceanic circulation; Oceanographic data; Oceanography; Physical oceanography; Saline intrusion; Tropical oceanography; Volume transport; Water exchange; Zonal flow (meteorology); ISW, Arabian Sea [Marine Regions]; ISW, Bangladesh [Marine Regions]; ISW, Bengal Bay [Marine Regions]; ISW, Indian Ocean [Marine Regions]; ISW, Sri Lanka [Marine Regions]; Marine

Authors  Top 
  • Schott, F.
  • Reppin, J.
  • Fischer, J.
  • Quadfasel, D.

    The zonal monsoon circulation south of India/Sri Lanka is a crucial link for the exchange between the northeastern and the northwestern Indian Ocean. The first direct measurements from moored stations and shipboard profiling on the seasonal and shorter-period variability of this flow are presented here. Of the three moorings deployed from January 1991 to February 1992 along 80°30'E between 4°11'N and 5°39'N, the outer two were equipped with upward looking acoustic Doppler current profilers (ADCPs) at 260-m depth. The moored and shipboard ADCP measurements revealed a very shallow structure of the near-surface flow, which was mostly confined to the top 100 m and required extrapolation of moored current shears toward the surface for transport calculations. During the winter monsoon, the westward flowing Northeast Monsoon Current (NMC) carried a mean transport of about 12 Sv in early 1991 and 10 Sv in early 1992. During the summer monsoon, transports in the eastward Southwest Monsoon Current (SMC) were about 8 Sv for the region north of 3°45'N, but the current might have extended further south, to 2°N, which would increase the total SMC transport to about 15 Sv. The circulation during the summer was sometimes found to be more complicated, with the SMC occasionally being separated from the Sri Lankan coast by a band of westward flowing low-salinity water originating in the Bay of Bengal. The annual-mean flow past Sri Lanka was weakly westward with a transport of only 2-3 Sv. Using seasonal-mean ship drift currents for surface values in the transport calculations yielded rather similar results to upward extrapolation of the moored profiles. The observations are compared with output of recent numerical models of the Indian Ocean circulation, which generally show the origin of the zonal flow past India/Sri Lanka to be at low latitudes and driven by the large-scale tropical wind field. Superimposed on this zonal circulation is local communication along the coast between the Bay of Bengal and the Arabian Sea.

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