The penetrative mixing in the Laptev Sea coastal polynya pycnocline layer.

Kirillov, Sergey A., Dmitrenko, Igor A., Hölemann, Jens A. , Kassens, Heidemarie and Bloshkina, Ekaterina (2013) The penetrative mixing in the Laptev Sea coastal polynya pycnocline layer. Continental Shelf Research, 63 . pp. 34-42. DOI 10.1016/j.csr.2013.04.040.

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Abstract

The large recurrent areas of open water and/or thin ice (polynyas) producing cold brine-enriched waters off the fast-ice edge are evident in the Laptev Sea in winter time. A number of abrupt positively correlated transitions in temperature and salinity were recorded in the bottom and intermediate layers at a mooring station in the West New Siberian (WNS) polynya in February-March 2008. Being in the range of -0.5 degrees C and -1.6 psu these changes are induced by horizontal motions across the polynya and correspond to temperature and salinity horizontal gradients in the range of 0.3-1.0 degrees C/10 km and 1.4-3.5 psu/10 km, respectively. The events of distinct freshening and temperature decrease coincide with a northward current off the fast-ice edge, while southward currents brought saltier and warmer waters at intermediate depths. We suggest that the observed transitions are connected to altering pycnocline depths across the polynya. The source of relatively fresher waters at the intermediate depths in polynya is supposed to originate from penetrative mixing of surface low salinity waters to intermediate water depth. Several forcing processes that could be responsible for a penetrative mixing through the density interface in polynya are discussed. These are penetrative convection and shear-driven mixing that originates from two-layer water dynamics and/or baroclinic tidal motions. The heavily ridged seaward fast-ice edge could produce an additional source of turbulent mixing even through a shear-free density interface due to the increased roughness at the ice-water interface

Document Type: Article
Additional Information: WOS:000321420500004
Keywords: Laptev Sea; Coastal polynya; Pycnocline; Penetrative mixing; Arctic Ocean; North water; Ice; Circulation; Turbulence; Simulation; Halocline; Shelf; Bay
Research affiliation: AWI
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.csr.2013.04.040
ISSN: 0278-4343
Projects: Transdrift, Laptev Sea System
Expeditions/Models/Experiments:
Date Deposited: 28 Aug 2013 08:38
Last Modified: 21 Sep 2016 08:30
URI: http://oceanrep.geomar.de/id/eprint/21938

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