Open AccessTide‐induced vertical mixing in the Laptev Sea coastal polynya
Author(s) -
Dmitrenko Igor A.,
Kirillov Sergey A.,
Bloshkina Ekaterina,
Lenn YuengDjern
Publication year - 2012
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jc006966
Subject(s) - baroclinity , geology , halocline , stratification (seeds) , mooring , thermocline , oceanography , amplitude , richardson number , homogeneous , acoustic doppler current profiler , turbulence , atmospheric sciences , current (fluid) , salinity , meteorology , seed dormancy , botany , germination , physics , quantum mechanics , dormancy , biology , thermodynamics
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 M 2 tidal 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.