Decay Mechanisms of Near-Inertial Mixed Layer Oscillations in the Bay of Bengal

Johnston, Shaun TM and Chaudhuri, Dipanjan and Mathur, Manikandan and Rudnick, Daniel L and Sengupta, Debasis and Simmons, Harper L and Tandon, Amit and Venkatesan, R (2016) Decay Mechanisms of Near-Inertial Mixed Layer Oscillations in the Bay of Bengal. In: OCEANOGRAPHY, 29 (2, SI). pp. 180-191.

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Abstract

Winds generate inertial and near-inertial currents in the upper ocean. These currents dominate the kinetic energy and contain most of the vertical shear in horizontal currents. Subsequent shear instabilities lead to mixing. In the Bay of Bengal, the annual mean wind energy input and near-inertial mixed layer energy is almost as large as in the mid-latitude storm tracks. Also, mixing associated with these waves is known to affect mixed layer heat content, sea surface temperature, and, thus, precipitation in coupled global models. Therefore, the mechanisms leading to the decay of these currents in the mixed layer and below are of considerable importance. Two such decay mechanisms are examined here. One mechanism is the downward propagation of near-inertial internal waves, which is aided by the mesoscale circulation and is observed with a rapidly profiling float. In a few days (faster than at mid-latitudes), the near-inertial wave group propagated from the base of the mixed layer to 250 m depth in the stratified interior. Another decay mechanism is enhanced shear generation at the mixed layer base from periodic alignment of rotating, near-inertial current shear and winds, which is observed with a mooring and analyzed with a simple two-layer model.

Item Type:	Journal Article
Publication:	OCEANOGRAPHY
Additional Information:	Copy right for this article belongs to the OCEANOGRAPHY SOC, P.O. BOX 1931, ROCKVILLE, MD USA
Department/Centre:	Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	08 Oct 2016 05:43
Last Modified:	08 Oct 2016 05:43
URI:	http://eprints.iisc.ac.in/id/eprint/54715

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