Nomenclature: Difference between revisions

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| <math>\varepsilon</math>
| <math>\varepsilon</math>
| Turbulent kinetic energy dissipation rate
| Viscous dissipation rate of turbulent kinetic energy per unit mass
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|  
| <math>\mathrm{W\, kg^{-1}}</math>
| <math>\mathrm{W\, kg^{-1}}</math>
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|-
| Ri
| Ri
| Richardson number
| (Gradient) Richardson number; the ratio of buoyancy freqency squared to velocity shear squared
| <math>Ri = \frac{N^2}{S^2}</math>
| <math>Ri = \frac{N^2}{S^2} </math>
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|  
|-
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| <math> Ri_f </math>
| Ri<math> _f</math>
| Flux gradient Richardson number
| Flux Richardson number; the ratio of the buoyancy flux to the shear production of turbulent kinetic energy
| <math>\frac{B}{P}</math> or Ivey & Imberger? Karan et cie
| <math>\frac{B}{P}</math>  
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|  
|-
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| <math>\kappa_\rho</math>
| <math>\kappa_\rho</math>
| Turbulent eddy diffusivity via Osborn's model
| Turbulent eddy diffusivity via the Osborn (1980) model
| <math>\kappa = \Gamma \varepsilon N^{-2}</math>  
| <math>\kappa = \Gamma \varepsilon N^{-2}</math>  
| <math>\mathrm{m^2\, s^{-1}}</math>
| <math>\mathrm{m^2\, s^{-1}}</math>
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! Units
! Units
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| <math>S_a</math>
| <math>S_P</math>
| Salinity
| Practical salinity
| <math> \sim 35 </math>
| -
|
| <math> - </math>
|-
| -
| T
| T
| Temperature
| Temperature
| <math>\sim -2 \rightarrow 40 </math>
| -
| <math> \mathrm{^{\circ}C } </math>
| <math> \mathrm{^{\circ}C } </math>
|-
|-
| P
| P
| Pressure
| Pressure
| <math>0\ \rightarrow\ \sim 1\times10^4</math>
|-
| <math>\mathrm{dbar} </math>
| <math>\mathrm{dbar} </math>
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|-

Revision as of 07:08, 29 October 2021


Background (total) velocity

---- MAKE SURE TO BE CONSISTENT WITH NETCDF TABLE --- ---- NETCDF TABLE will have own page (periodic copy&paste of excel sheet)---


Symbol Description Units
u zonal velocity ms−1
v meridional velocity ms−1
ue error velocity ms−1
V velocity perpendicular to mean flow ms−1
Wd Profiler fall speed ms−1
UP Flow speed past sensor ms−1
b Along-beam velocity from acoustic Doppler sensor ms−1
b′ Along-beam velocity from acoustic Doppler sensor with background flow deducted ms−1
δz Vertical size of measurement bin for acoustic Doppler sensor m
r Along-beam distance from acoustic Doppler sensor m
δr Along-beam bin size for acoustic Doppler sensor m
θ Beam transmit and receive angle relative to instrument axis for acoustic Doppler sensor ∘

Turbulence properties

Symbol Description Eqn Units
ε Viscous dissipation rate of turbulent kinetic energy per unit mass Wkg−1
Ri (Gradient) Richardson number; the ratio of buoyancy freqency squared to velocity shear squared Ri=N2S2
Rif Flux Richardson number; the ratio of the buoyancy flux to the shear production of turbulent kinetic energy BP
κρ Turbulent eddy diffusivity via the Osborn (1980) model κ=ΓεN−2 m2s−1
DLL Second-order longitudinal structure function DLL=⟨[b′(r)−b′(r+nδr)]2⟩ m2s−2

Fluid properties and background gradients for turbulence calculations

Symbol Description Eqn Units
SP Practical salinity - − - T Temperature - ∘C
P Pressure
dbar
ρ Density of water ρ=ρ(T,Sa,P) kgm−3
α Temperature coefficient of expansion α=1ρ∂ρ∂T K−1
β Saline coefficient of contraction β=1ρ∂ρ∂Sa
S Background velocity shear S=((∂U∂z)2+(∂V∂z)2)1/2 s−1
ν35 Temperature dependent kinematic viscosity of seawater at a salinity of 35 ∼1×10−6 m2s−1
ν00 Temperature dependent kinematic viscosity of freshwater ∼1×10−6 m2s−1
Γ Adiabatic temperature gradient -- salinity, temperature and pressure dependent ∼1×10−4 Kdbar−1
N Background stratification, i.e buoyancy frequency N2=g[α(Γ+∂T∂z)−β∂Sa∂z] rads−1

Theoretical Length and Time Scales

Symbol Description Eqn Units
τN Buoyancy timescale τN=1N s
TN Buoyancy period TN=2πN s
LE Ellison length scale (limit of vertical displacement without irreversible mixing) LE=⟨ρ'2⟩1/2∂ρ‾/∂z m
Lρ Density length scale Lρ m
LS Corssin length scale LS=ε/S3 m
η Kolmogorov length scale (smallest overturns) η=(ν3ε)1/4 m
LK Kolmogorov length scale (smallest overturns) LK=(ν3ε)1/4 m
Lo Ozmidov length scale, measure of largest overturns in a stratified fluid Lo=(εN3)1/2 m
LT Thorp length scale LT m

Turbulence Spectrum

These variables are used to express the Turbulence spectrum expected shapes.


Symbol Description Eqn Units
Δt Sampling interval 1fs s
fs Sampling rate fs=1Δt s−1
Δs Sample spacing Δs=UPΔt m
Δl Linear dimension of sampling volume (instrument dependent) m
f Cyclic frequency f=ω2π Hz
ω Angular frequency ω=2πf rads−1
fN Nyquist frequency fN=0.5fs Hz
k Cyclic wavenumber k=fUP cpm
k̂ Angular wavenumber k̂=ωUP=2πk radm−1
kΔ Nyquist wavenumber, based on sampling volume size Δl kΔ=0.5Δl cpm
kN Nyquist wavenumber, via Taylor's hypothesis kN=fNUP cpm
Ψvariable(k) Theoretical, empirical or model spectrum of any given variable units of the variable squared/units of k (i.e.,cpm)
Φvariable(k) Observed spectrum of any given variable units of the variable squared/units of k (i.e.,cpm)