scholarly journals Note on the bulk estimate of the energy dissipation rate in the bottom boundary layer

2021 ◽  
Author(s):  
Xiaozhou Ruan
Keyword(s):  
Boundary Layer ◽  
Energy Dissipation ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
Bottom Boundary Layer ◽  
Bottom Boundary

Update on the Global Energy Dissipation Rate of Deep-Ocean Low-Frequency Flows by Bottom Boundary Layer

2018 ◽  
Vol 48 (6) ◽  
pp. 1243-1255 ◽  
Author(s):  
Chao Huang ◽  
Yongsheng Xu
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Dissipation Rate ◽  
Low Frequency ◽  
Deep Ocean ◽  
Power Input ◽  
Energy Dissipation Rate ◽  
Bottom Boundary Layer ◽  
Geostrophic Currents ◽  
Bottom Boundary

AbstractThe global dissipation caused by bottom boundary layer drag is one of the major pathways for the consumption of kinetic energy in the deep ocean. However, the spatial distribution and global integral of the drag dissipation are still debatable. This paper presents an updated estimate of the dissipation rate, using the barotropic component of surface geostrophic currents and 632 in situ velocity measurements. Also, the seafloor roughness is proposed as a parameter of drag efficiency in the parameterized method. The results provide a map of the drag dissipation rate with a global integral of ~0.26 TW. Approximately 66% of this dissipation occurs in the Southern Ocean, which is consistent with the proportion of wind power input into this region. Building upon the work in previous studies on the bottom boundary layer drag, more long-period observations are used, eliminating the influence of the baroclinic contribution to the surface geostrophic currents in the construction of the bottom velocity, and taking topographic roughness into account. The estimates have implications for the maintenance of density structure in the deep ocean and understanding of the kinetic energy budget.

scholarly journals Stratified Inertial Subrange Inferred from In Situ Measurements in the Bottom Boundary Layer of the Rockall Channel

2010 ◽  
Vol 40 (11) ◽  
pp. 2401-2417 ◽  
Author(s):  
Pascale Bouruet-Aubertot ◽  
Hans van Haren ◽  
M. Pascale Lelong
Keyword(s):  
Boundary Layer ◽  
Energy Levels ◽  
Deep Ocean ◽  
Energy Dissipation Rate ◽  
Bottom Boundary Layer ◽  
Inertial Subrange ◽  
Buoyancy Frequency ◽  
Bottom Boundary ◽  
Wide Range ◽  
Taylor Hypothesis

Abstract Deep-ocean high-resolution moored temperature data are analyzed with a focus on superbuoyant frequencies. A local Taylor hypothesis based on the horizontal velocity averaged over 2 h is used to infer horizontal wavenumber spectra of temperature variance. The inertial subrange extends over fairly low horizontal wavenumbers, typically within 2 × 10−3 and 2 × 10−1 cycles per minute (cpm). It is therefore interpreted as a stratified inertial subrange for most of this wavenumber interval, whereas in some cases the convective inertial subrange is resolved as well. Kinetic energy dissipation rate ε is inferred using theoretical expressions for the stratified inertial subrange. A wide range of values within 10−9 and 4 × 10−7 m2 s−3 is obtained for time periods either dominated by semidiurnal tides or by significant subinertial variability. A scaling for ε that depends on the potential energy within the inertio-gravity waves (IGW) frequency band PEIGW and the buoyancy frequency N is proposed for these two cases. When semidiurnal tides dominate, ε ≃ (PEIGWN)3/2, whereas ε ≃ PEIGWN in the presence of significant subinertial variability. This result is obtained for energy levels ranging from 1 to 30 times the Garrett–Munk energy level and is in contrast with classical finescale parameterization in which ε ∼ (PEIGW)2 that applies far from energy sources. The specificities of the stratified bottom boundary layer, namely a weak stratification, may account for this difference.

Tidal energy fluxes and bottom boundary layer energy dissipation in the Bering Sea

2010 ◽  
Vol 9 (3) ◽  
pp. 340-346 ◽  
Author(s):  
Pei-liang Li ◽  
Juan Zhou ◽  
Lei Li ◽  
Wei Zhao ◽  
Chang-lin Chen
Keyword(s):  
Boundary Layer ◽  
Energy Dissipation ◽  
Bering Sea ◽  
Tidal Energy ◽  
Bottom Boundary Layer ◽  
Energy Fluxes ◽  
Bottom Boundary ◽  
The Bering Sea

scholarly journals A Self-Contained Acoustic Scintillation Instrument for Path-Averaged Measurements of Flow and Turbulence with Application to Hydrothermal Vent and Bottom Boundary Layer Dynamics

2005 ◽  
Vol 22 (10) ◽  
pp. 1602-1617 ◽  
Author(s):  
D. Di Iorio ◽  
D. Lemon ◽  
R. Chave
Keyword(s):  
Boundary Layer ◽  
Hydrothermal Vent ◽  
Acoustic Scattering ◽  
Temperature Fluctuations ◽  
Energy Dissipation Rate ◽  
Bottom Boundary Layer ◽  
The Black Sea ◽  
Small Scale ◽  
Bottom Boundary

Abstract A self-contained acoustical scintillation instrument is described that has been used to measure flow and turbulence characteristics in two diverse oceanographic settings. This instrument is a battery-operated and internally logging acoustic propagation system that is ideally suited to monitor long-term flow and small-scale effective refractive index fluctuations. When the temperature variability dominates the acoustic scattering, as is the case of a hydrothermal vent plume, then a measure of the vertical buoyancy-driven flow, together with the root-mean-square temperature fluctuations, can be obtained. Results for vent structure Hulk of the Main Endeavour vent field of the Juan de Fuca Ridge show that the long-term (71 days) temperature fluctuations, together with the vertical flow, can be used to estimate heat flux density. Measurements also show oscillations in the log-amplitude variance that result from plume advection by the ambient tidal currents and demonstrate the need for a long time series measurement. When the turbulent velocity dominates the acoustic scattering, as is the case in some energetic bottom boundary layer flows, then the turbulent kinetic energy dissipation rate is derived, assuming isotropic and homogeneous models. The methodology and results are summarized from an application to the Bosporus Canyon of the Black Sea, to monitor the flow and turbulence associated with Mediterranean seawater inflow.

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