Oceanography The Official Magazine of
The Oceanography Society
Volume 29 Issue 02

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Volume 29, No. 2
Pages 112 - 123


Observations of Currents Over the Deep Southern Bay of Bengal—With a Little Luck

By Hemantha W. Wijesekera , William J. Teague, Ewa Jarosz, David W. Wang, Tommy G. Jensen, S.U.P. Jinadasa , Harindra J.S. Fernando , Luca R. Centurioni , Zachariah R. Hallock , Emily L. Shroyer , and James N. Moum 
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Article Abstract

Long-term time series of velocity, hydrographic, and turbulence fields were collected from a six-element subsurface mooring array in the southern Bay of Bengal. The moorings, deployed in December 2013 and recovered in August 2015, were entangled with commercial fishing nets and lines, while top subsurface buoys ended up being serendipitously closer to the surface than planned. In spite of these unexpected events, almost all the sensors and data were recovered. The moorings provided currents between 6 m and 500 m depths from acoustic Doppler current profilers, supplemented by hydrographic data and turbulent dissipation rates at selected depths. The observations captured the summer and winter monsoon currents, eddies, and intraseasonal oscillations. Near-surface currents as large as 1.75 m s–1 were observed in July 2014. Currents stronger than 0.5 m s–1 were confined to the upper 200 m. Observations of currents, temperature, and sea surface height (SSH) fields revealed eddylike features with positive and negative SSH anomalies (~20 cm) moving westward at speeds of about 0.1 m s–1. Intraseasonal oscillations with periods of 30 to 90 days were strongest near the surface. For the duration of the deployment, root-mean-square velocity fluctuations were about 0.1 m s–1 near the surface but decayed with depth and became nearly uniform (~0.03–0.06 m s–1) below 100 m. 


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