Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
Ocean Sci., 13, 1035-1044, 2017
https://doi.org/10.5194/os-13-1035-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
07 Dec 2017
An undercurrent off the east coast of Sri Lanka
Arachaporn Anutaliya1, Uwe Send1, Julie L. McClean1, Janet Sprintall1, Luc Rainville2, Craig M. Lee2, S. U. Priyantha Jinadasa3, Alan J. Wallcraft4, and E. Joseph Metzger5 1Scripps Institution of Oceanography, La Jolla, California, USA
2Applied Physics Laboratory, University of Washington, Seattle, Washington, USA
3National Aquatic Resources Research and Development Agency (NARA) Crow Island, Colombo 15, Sri Lanka
4Center for Ocean–Atmospheric Prediction Studies (COAPS), Florida State University, Tallahassee, Florida, USA
5Naval Research Laboratory, Stennis Space Center, Mississippi, USA
Abstract. The existence of a seasonally varying undercurrent along 8° N off the east coast of Sri Lanka is inferred from shipboard hydrography, Argo floats, glider measurements, and two ocean general circulation model simulations. Together, they reveal an undercurrent below 100–200 m flowing in the opposite direction to the surface current, which is most pronounced during boreal spring and summer and switches direction between these two seasons. The volume transport of the undercurrent (200–1000 m layer) can be more than 10 Sv in either direction, exceeding the transport of 1–6 Sv carried by the surface current (0–200 m layer). The undercurrent transports relatively fresher water southward during spring, while it advects more saline water northward along the east coast of Sri Lanka during summer. Although the undercurrent is potentially a pathway of salt exchange between the Arabian Sea and the Bay of Bengal, the observations and the ocean general circulation models suggest that the salinity contrast between seasons and between the boundary current and interior is less than 0.09 in the subsurface layer, suggesting a small salt transport by the undercurrent of less than 4 % of the salinity deficit in the Bay of Bengal.

Citation: Anutaliya, A., Send, U., McClean, J. L., Sprintall, J., Rainville, L., Lee, C. M., Jinadasa, S. U. P., Wallcraft, A. J., and Metzger, E. J.: An undercurrent off the east coast of Sri Lanka, Ocean Sci., 13, 1035-1044, https://doi.org/10.5194/os-13-1035-2017, 2017.
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Short summary
Observations and numerical models reveal the existence of the subsurface current in the opposite direction to the surface current off the Sri Lankan east coast. The undercurrent (200–1000 m layer) is most pronounced during the boreal spring and summer and transports more mass than the surface layer (0–200 m). Although the undercurrent is potentially a pathway of salt exchange between the Arabian Sea and the Bay of Bengal, the data and models suggest little salt transport by the undercurrent.
Observations and numerical models reveal the existence of the subsurface current in the opposite...
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