Near-surface horizontal convergence and dispersion near the tidal-mixing front on Northeastern Georges Bank

2001 ◽  
Vol 48 (1-3) ◽  
pp. 311-339 ◽  
Author(s):  
Kenneth F. Drinkwater ◽  
John W. Loder
Keyword(s):  
Tidal Mixing ◽  
Georges Bank ◽  
Near Surface ◽  
Tidal Mixing Front

7. Tidal mixing

2019 ◽  
pp. 98-115
Author(s):  
David George Bowers ◽  
Emyr Martyn Roberts
Keyword(s):  
Water Depth ◽  
Deep Ocean ◽  
Tidal Currents ◽  
The Other ◽  
Tidal Mixing ◽  
Shelf Seas ◽  
Tidal Mixing Front ◽  
Tidal Streams

‘Tidal mixing’ describes tidal mixing in shelf seas, where the water is shallow and tidal currents can be much faster than in the deep ocean. Most of the energy lost from the tide through friction is first converted into turbulence, which then makes a very effective mixing mechanism, stirring the Sun’s heat downwards. Shelf seas at temperate latitudes in summer are divided into stratified regions and vertically mixed regions, depending on the tidal streams’ strength and the water depth. The transition from one to the other happens rapidly and creates a tidal mixing front. Tidal mixing in estuaries is also discussed along with the harnessing of tides to generate electricity.

Circulation, hydrographic structure and mixing at tidal fronts: the view from Georges Bank

1993 ◽  
Vol 343 (1669) ◽  
pp. 447-460 ◽  
Keyword(s):  
Field Studies ◽  
Temporal Variations ◽  
Tidal Mixing ◽  
Small Scale ◽  
Georges Bank ◽  
Tidal Period ◽  
Hydrographic Structure ◽  
Frontal Structure ◽  
Northern Side ◽  
Scale Turbulence

The steep slope on the northern side of Georges Bank and its location in the Fundy-Maine tidal system result in a persistent summertime frontal system comprising a tidal-mixing front and a stratified tide-topography interaction at the Bank edge. Recent field studies have provided a high-resolution description of the circulation, hydrographic structure and mixing in the region. Frontal features include an along-front residual jet, a surface convergence zone, regular variations in frontal structure and position over the tidal period and tidal modulation cycle, largeamplitude internal waves, and strong spatial and temporal variations in small-scale turbulence. The observations suggest that the magnitude of cross-front and vertical exchange in frontal regions can be site-specific depending on the relative importance of the underlying physical processes.

Biological studies in the vicinity of a shallow-sea tidal mixing front. I. Physical and chemical background

1985 ◽  
Vol 310 (1146) ◽  
pp. 407-433 ◽  
Keyword(s):  
Ammonium Nitrogen ◽  
Tidal Mixing ◽  
Irish Sea ◽  
Total Biomass ◽  
Shallow Sea ◽  
High Biological Activity ◽  
Biological Studies ◽  
Chemical Background ◽  
Tidal Mixing Front ◽  
Physical And Chemical

A study has been made of the distribution and activities of bacteria and zooplankton as they varied seasonally in 1980 and 1981 in the vicinity of a shallow-sea tidal mixing front in the western Irish Sea (approximate position 53° 20' N, 5° 45' W to 53° 50' N, 5° 0' W ). This paper presents the physical and chemical background to these studies as shown by the variations in temperature and salinity and concentrations of chlorophyll a , phaeopigments, cellular adenosine triphosphate (ATP), nitrate, nitrite and ammonium nitrogen, in sections normal to the front. Observations at drogue stations were made to establish the extent of diurnal variations in these properties but these appeared to be small relative to other variations. As the front developed, higher chlorophyll a concentrations appeared in the surface stratified water, in contrast to the bottom stratified water and mixed water, with highest concentrations at the surface at the stratified side of the front and in subsurface patches in the vicinity of the pycnocline. As the phytoplankton populations increased nitrate became depleted in the surface stratified water but nitrite and ammonium nitrogen concentrations remained at about the same levels. Cellular ATP concentration did not appear to be a useful measure of total biomass but indicated high biological activity in the surface stratified water.

The effects of a tidal-mixing front on the distribution of larval fish habitats in a semi-enclosed sea during winter

2014 ◽  
Vol 94 (7) ◽  
pp. 1517-1530 ◽  
Author(s):  
Emilio A. Inda-Díaz ◽  
Laura Sánchez-Velasco ◽  
Miguel F. Lavín
Keyword(s):  
Gulf Of California ◽  
Larval Fish ◽  
Three Dimensional ◽  
Wide Distribution ◽  
Tidal Mixing ◽  
Larval Abundance ◽  
North West ◽  
North East ◽  
Tidal Mixing Front ◽  
Fish Habitats

We examined the effect of a tidal-mixing front on the three-dimensional distribution of larval fish habitats (LFHs) in the Midriff Archipelago Region in the Gulf of California during winter. Zooplankton and environmental variables were sampled from 0 to 200 m in 50 m strata. Four LFHs were defined in association with the front, two on the northern side and two on the southern side. The northern LFHs were: (1) the Mainland Shelf Habitat, located from the surface to 100 m depth on the north-east mainland shelf, characterized mainly by the presence of Citharichtys fragilis; and (2) the Wide Distribution Habitat, extending from north-west to south across the front from the surface to 200 m depth, dominated by the ubiquitous Engraulis mordax. The southern LFHs were: (3) the Eddy Zone Habitat, defined nearly on an anticyclonic eddy, with the highest larval abundance and richness from the surface to 100 m depth, dominated by Leuroglossus stilbius; and (4) the Southern Gulf Habitat, associated with low temperature waters from the southern Gulf of California, dominated by southern-gulf species (e.g. Scomber japonicus and Sardinops sagax). Despite the weak stratification and low thermal contrast (~1.5°C) across the south front compared to summer (~3°C), our results demonstrate that the frontal zone may influence the formation of planktonic habitats even during generally homogeneous periods, which may also be relevant in other regions of the world.

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