Tide-induced vertical mixing in the Laptev Sea coastal polynya.

Dmitrenko, Igor A., Kirillov, Sergey A., Bloshkina, Ekaterina and Lenn, Yueng-Djern (2012) Tide-induced vertical mixing in the Laptev Sea coastal polynya. Open Access Journal of Geophysical Research: Oceans, 117 . C00G14. DOI 10.1029/2011JC006966.

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Abstract

Enhanced semidiurnal-band velocity shear across the shelf halocline layer (SHL) was found during land-fast ice edge mooring-based acoustic Doppler current profiler (ADCP) and conductivity-temperature-depth (CTD) observations over the eastern Laptev Sea shelf (∼74°N, 128°E) in April–May 2008 and April 2009. In 2008, the major axis amplitude for the lunar semidiurnal M2tidal ellipses demonstrated intermediate maximum in the SHL at 11–13 m (15 ± 3 cm/s), gradually decreasing to subice and near-bottom layers to ∼9 ± 3 cm/s (at 7 m) and 7 ± 2 cm/s (at 19 m), respectively. In 2009, the semidiurnal tidal flow exhibited similar patterns, but velocities were reduced by about factor of 2. Our estimates of gradient Richardson numbers suggest that the velocity shear associated with semidiurnal baroclinic tidal flow may be strong enough to play a role in water mass modification, promoting shear instabilities, turbulence, and vertical mixing of seawater properties across the SHL. This suggestion is consistent with near-homogeneous water layers episodically occurring in the SHL. Differences in the background stratification and local tidal dynamics between 2008 and 2009, together with rapid responses of the semidiurnal motion to polynya openings, suggest that the baroclinic tide is locally generated.

Document Type: Article
Keywords: Baroclinic tide; Coastal polynya; Shelf halocline layer; Vertical mixing
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2011JC006966
ISSN: 2169-9275
Projects: Polynya, Laptev Sea System
Date Deposited: 02 Dec 2014 11:52
Last Modified: 27 Feb 2018 08:49
URI: http://oceanrep.geomar.de/id/eprint/26094

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