Arachaporn Anutaliya1,Uwe Send1,Julie L. McClean1,Janet Sprintall1,Luc Rainville2,Craig M. Lee2,S. U. Priyantha Jinadasa3,Alan J. Wallcraft4,and E. Joseph Metzger5Arachaporn Anutaliya et al. 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
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
Received: 10 May 2017 – Discussion started: 11 Jul 2017 – Revised: 13 Oct 2017 – Accepted: 20 Oct 2017 – Published: 07 Dec 2017
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.
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...
