scholarly journals CURRENT ACTIVITY IN THE THERMAIKOS GULF CONTINENTAL MARGIN , IN RELAÏJON TO MODERN SEDIMENTATION PROCESSES

2018 ◽  
Vol 36 (2) ◽  
pp. 1103
Author(s):  
S. E. Poulos ◽  
P. G. Drakopoulos
Keyword(s):  
Continental Margin ◽  
Internal Tide ◽  
Aegean Sea ◽  
Submarine Canyon ◽  
Basin Surface ◽  
Bed Roughness ◽  
Wind Events ◽  
Inertial Currents ◽  
Seabed Sediments ◽  
Sedimentation Processes

The area under investigation represents the NW continental margin of the Aegean Sea i.e. the Thermaikos Gulf and the associated NW Sporades Basin. Surficial seabed sediments are of terrigenous origin whilst in terms of grain size, offshore sediments maybe distinguished into silty sediments that cover the northern and western part of the Gulf; clayey that cover the floor of the Sporades basin and relict sands that cover mainly the central and eastern part of the self. Current meter measurements from different water depths were obtained from 10 stations on the shelf, shelf/break, within canyons and in the Sporades Basin. Surface currents over the period of the investigation are dominated by inertial currents generated by wind events. Inertial period currents also dominate the near-bed currents on the continental shelf and in Sporades Basin. On the canyon slope, however, tidal currents are the dominant ones; these relate to the amplification of the internal tide, within the submarine canyon. Measured near-bed currents are below the threshold for sediment movement in the case of flat seabeds, although they are capable to inhibit deposition of the settling clayey particles. This contributes also to a further offshore dispersal of riverine sediments. Moreover, increased bed roughness due to benthic activity can cause resuspension for lower current speeds.

Energetics of Barotropic and Baroclinic Tides in the Monterey Bay Area

2012 ◽  
Vol 42 (2) ◽  
pp. 272-290 ◽  
Author(s):  
Dujuan Kang ◽  
Oliver Fringer
Keyword(s):  
Energy Flux ◽  
Three Dimensional ◽  
Internal Tide ◽  
Submarine Canyon ◽  
Tidal Energy ◽  
Energy Partitioning ◽  
Navier Stokes ◽  
Monterey Bay ◽  
Topographic Features ◽  
Bay Area

Abstract A detailed energy analysis of the barotropic and baroclinic M2 tides in the Monterey Bay area is performed. The authors first derive a theoretical framework for analyzing internal tide energetics based on the complete form of the barotropic and baroclinic energy equations, which include the full nonlinear and nonhydrostatic energy flux contributions as well as an improved evaluation of the available potential energy. This approach is implemented in the Stanford Unstructured Nonhydrostatic Terrain-Following Adaptive Navier–Stokes Simulator (SUNTANS). Results from three-dimensional, high-resolution SUNTANS simulations are analyzed to estimate the tidal energy partitioning among generation, radiation, and dissipation. A 200 km × 230 km domain including all typical topographic features in this region is used to represent the Monterey Bay area. Of the 152-MW energy lost from the barotropic tide, approximately 133 MW (88%) is converted into baroclinic energy through internal tide generation, and 42% (56 MW) of this baroclinic energy radiates away into the open ocean. The tidal energy partitioning depends greatly on the topographic features. The Davidson Seamount is most efficient at baroclinic energy generation and radiation, whereas the Monterey Submarine Canyon acts as an energy sink. Energy flux contributions from nonlinear and nonhydrostatic effects are also examined. In the Monterey Bay area, the nonlinear and nonhydrostatic contributions are quite small. Moreover, the authors investigate the character of internal tide generation and find that in the Monterey Bay area the generated baroclinic tides are mainly linear and in the form of internal tidal beams. Comparison of the modeled tidal conversion to previous theoretical estimates shows that they are consistent with one another.

Observation of internal tide-induced nutrient upwelling in Hungtsai Trough, a submarine canyon in the northern South China Sea

2016 ◽  
Vol 120 ◽  
pp. 59-67 ◽  
Author(s):  
Su-Cheng Pai ◽  
Ching-Ling Wei ◽  
Saulwood Lin ◽  
Liang-Saw Wen ◽  
Chun-Mao Tseng
Keyword(s):  
South China Sea ◽  
South China ◽  
Northern South China Sea ◽  
Internal Tide ◽  
Submarine Canyon ◽  
China Sea

scholarly journals Internal Tide Convergence and Mixing in a Submarine Canyon

2017 ◽  
Vol 47 (2) ◽  
pp. 303-322 ◽  
Author(s):  
Amy F. Waterhouse ◽  
Jennifer A. Mackinnon ◽  
Ruth C. Musgrave ◽  
Samuel M. Kelly ◽  
Andy Pickering ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Internal Wave ◽  
Wave Energy ◽  
Internal Tide ◽  
Submarine Canyon ◽  
Internal Tides ◽  
North Coast ◽  
Semidiurnal Tide ◽  
The North ◽  
Tidally Driven

AbstractObservations from Eel Canyon, located on the north coast of California, show that elevated turbulence in the full water column arises from the convergence of remotely generated internal wave energy. The incoming semidiurnal and bottom-trapped diurnal internal tides generate complex interference patterns. The semidiurnal internal tide sets up a partly standing wave within the canyon due to reflection at the canyon head, dissipating all of its energy within the canyon. Dissipation in the near bottom is associated with the diurnal trapped tide, while midwater isopycnal shear and strain is associated with the semidiurnal tide. Dissipation is elevated up to 600 m off the bottom, in contrast to observations over the flat continental shelf where dissipation occurs closer to the topography. Slope canyons are sinks for internal wave energy and may have important influences on the global distribution of tidally driven mixing.

Calculating Global Dissipation of Internal Tides in Submarine Canyons

2021 ◽  
Author(s):  
Robert Nazarian ◽  
Christian Burns ◽  
Sonya Legg ◽  
Maarten Buijsman ◽  
Brian Arbic
Keyword(s):  
Internal Tide ◽  
Submarine Canyon ◽  
Internal Gravity Waves ◽  
Internal Tides ◽  
Global Ocean ◽  
Submarine Canyons ◽  
Incoming Wave ◽  
Geometrical Properties ◽  
Length Width ◽  
Global Estimates

<p>The breaking of tidally-generated internal gravity waves (hereafter internal tides) is a significant driver of ocean mixing, and observations and model simulations show that a non-negligible amount of this internal tide-driven mixing occurs in submarine canyons. While previous studies have used single observations of canyon mixing to estimate the global magnitude of internal tide-driven mixing within canyons, there is still significant uncertainty in these estimates.</p><p>To address this question, we have constructed an algorithm based on the modelled energy loss in idealized simulations (Nazarian & Legg 2017b) to calculate the magnitude of mixing in each submarine canyon and to determine the percentage of the global internal tide energy budget that is dissipated in canyons. The algorithm utilizes the Harris et al. 2014 analysis of the SRTM30_PLUS global bathymetry map to provide the geometrical properties of each canyon (i.e. height, length, width) and a high-resolution, tidally-forced HYCOM simulation to determine the internal tide field (sea surface height, angle of propagation, stratification, etc.). Preliminary calculations show that the canyon’s geometrical properties as well as local hydrographic properties have significant effects on the magnitude of mixing. Specifically, canyons that are tall relative to the depth of the water column and long relative to the incoming internal tide’s wavelength dissipate approximately 100% of the incoming wave’s energy. Consistent with previous studies, we find that regardless of bathymetry, submarine canyons can dissipate a significant fraction of the incident internal tide energy. Our estimate of the globally-integrated energy dissipation in canyons, taking into account geometric properties of each canyon, is two to three times larger than prior global estimates extrapolated from observations of individual canyons. Furthermore, our research highlights canyon hotspots of internal tide-driven mixing in the global ocean, for which observations do not presently exist. Taken together, these results raise larger questions about the location of internal tide dissipation and the inclusion of such dissipation in global ocean models.</p>

Late Weichselian–Holocene evolution of the high-latitude Andøya submarine Canyon, North-Norwegian continental margin

2015 ◽  
Vol 363 ◽  
pp. 1-14 ◽  
Author(s):  
Hilde B. Amundsen ◽  
Jan Sverre Laberg ◽  
Tore O. Vorren ◽  
Haflidi Haflidason ◽  
Matthias Forwick ◽  
...  
Keyword(s):  
Continental Margin ◽  
High Latitude ◽  
Submarine Canyon ◽  
Late Weichselian
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