Changeset 11123 for NEMO/trunk/doc/latex/NEMO/subfiles/chap_ZDF.tex
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r10442 r11123 87 87 a dependency between the vertical eddy coefficients and the local Richardson number 88 88 (\ie the ratio of stratification to vertical shear). 89 Following \citet{ Pacanowski_Philander_JPO81}, the following formulation has been implemented:89 Following \citet{pacanowski.philander_JPO81}, the following formulation has been implemented: 90 90 \[ 91 91 % \label{eq:zdfric} … … 124 124 The final $h_{e}$ is further constrained by the adjustable bounds \np{rn\_mldmin} and \np{rn\_mldmax}. 125 125 Once $h_{e}$ is computed, the vertical eddy coefficients within $h_{e}$ are set to 126 the empirical values \np{rn\_wtmix} and \np{rn\_wvmix} \citep{ Lermusiaux2001}.126 the empirical values \np{rn\_wtmix} and \np{rn\_wvmix} \citep{lermusiaux_JMS01}. 127 127 128 128 % ------------------------------------------------------------------------------------------------------------- … … 140 140 a prognostic equation for $\bar{e}$, the turbulent kinetic energy, 141 141 and a closure assumption for the turbulent length scales. 142 This turbulent closure model has been developed by \citet{ Bougeault1989} in the atmospheric case,143 adapted by \citet{ Gaspar1990} for the oceanic case, and embedded in OPA, the ancestor of NEMO,144 by \citet{ Blanke1993} for equatorial Atlantic simulations.145 Since then, significant modifications have been introduced by \citet{ Madec1998} in both the implementation and142 This turbulent closure model has been developed by \citet{bougeault.lacarrere_MWR89} in the atmospheric case, 143 adapted by \citet{gaspar.gregoris.ea_JGR90} for the oceanic case, and embedded in OPA, the ancestor of NEMO, 144 by \citet{blanke.delecluse_JPO93} for equatorial Atlantic simulations. 145 Since then, significant modifications have been introduced by \citet{madec.delecluse.ea_NPM98} in both the implementation and 146 146 the formulation of the mixing length scale. 147 147 The time evolution of $\bar{e}$ is the result of the production of $\bar{e}$ through vertical shear, 148 its destruction through stratification, its vertical diffusion, and its dissipation of \citet{ Kolmogorov1942} type:148 its destruction through stratification, its vertical diffusion, and its dissipation of \citet{kolmogorov_IANS42} type: 149 149 \begin{equation} 150 150 \label{eq:zdftke_e} … … 168 168 $P_{rt}$ is the Prandtl number, $K_m$ and $K_\rho$ are the vertical eddy viscosity and diffusivity coefficients. 169 169 The constants $C_k = 0.1$ and $C_\epsilon = \sqrt {2} /2$ $\approx 0.7$ are designed to deal with 170 vertical mixing at any depth \citep{ Gaspar1990}.170 vertical mixing at any depth \citep{gaspar.gregoris.ea_JGR90}. 171 171 They are set through namelist parameters \np{nn\_ediff} and \np{nn\_ediss}. 172 $P_{rt}$ can be set to unity or, following \citet{ Blanke1993}, be a function of the local Richardson number, $R_i$:172 $P_{rt}$ can be set to unity or, following \citet{blanke.delecluse_JPO93}, be a function of the local Richardson number, $R_i$: 173 173 \begin{align*} 174 174 % \label{eq:prt} … … 185 185 At the sea surface, the value of $\bar{e}$ is prescribed from the wind stress field as 186 186 $\bar{e}_o = e_{bb} |\tau| / \rho_o$, with $e_{bb}$ the \np{rn\_ebb} namelist parameter. 187 The default value of $e_{bb}$ is 3.75. \citep{ Gaspar1990}), however a much larger value can be used when187 The default value of $e_{bb}$ is 3.75. \citep{gaspar.gregoris.ea_JGR90}), however a much larger value can be used when 188 188 taking into account the surface wave breaking (see below Eq. \autoref{eq:ZDF_Esbc}). 189 189 The bottom value of TKE is assumed to be equal to the value of the level just above. … … 191 191 the numerical scheme does not ensure its positivity. 192 192 To overcome this problem, a cut-off in the minimum value of $\bar{e}$ is used (\np{rn\_emin} namelist parameter). 193 Following \citet{ Gaspar1990}, the cut-off value is set to $\sqrt{2}/2~10^{-6}~m^2.s^{-2}$.194 This allows the subsequent formulations to match that of \citet{ Gargett1984} for the diffusion in193 Following \citet{gaspar.gregoris.ea_JGR90}, the cut-off value is set to $\sqrt{2}/2~10^{-6}~m^2.s^{-2}$. 194 This allows the subsequent formulations to match that of \citet{gargett_JMR84} for the diffusion in 195 195 the thermocline and deep ocean : $K_\rho = 10^{-3} / N$. 196 196 In addition, a cut-off is applied on $K_m$ and $K_\rho$ to avoid numerical instabilities associated with … … 202 202 203 203 For computational efficiency, the original formulation of the turbulent length scales proposed by 204 \citet{ Gaspar1990} has been simplified.204 \citet{gaspar.gregoris.ea_JGR90} has been simplified. 205 205 Four formulations are proposed, the choice of which is controlled by the \np{nn\_mxl} namelist parameter. 206 The first two are based on the following first order approximation \citep{ Blanke1993}:206 The first two are based on the following first order approximation \citep{blanke.delecluse_JPO93}: 207 207 \begin{equation} 208 208 \label{eq:tke_mxl0_1} … … 212 212 The resulting length scale is bounded by the distance to the surface or to the bottom 213 213 (\np{nn\_mxl}\forcode{ = 0}) or by the local vertical scale factor (\np{nn\_mxl}\forcode{ = 1}). 214 \citet{ Blanke1993} notice that this simplification has two major drawbacks:214 \citet{blanke.delecluse_JPO93} notice that this simplification has two major drawbacks: 215 215 it makes no sense for locally unstable stratification and the computation no longer uses all 216 216 the information contained in the vertical density profile. 217 To overcome these drawbacks, \citet{ Madec1998} introduces the \np{nn\_mxl}\forcode{ = 2..3} cases,217 To overcome these drawbacks, \citet{madec.delecluse.ea_NPM98} introduces the \np{nn\_mxl}\forcode{ = 2..3} cases, 218 218 which add an extra assumption concerning the vertical gradient of the computed length scale. 219 219 So, the length scales are first evaluated as in \autoref{eq:tke_mxl0_1} and then bounded such that: … … 225 225 \autoref{eq:tke_mxl_constraint} means that the vertical variations of the length scale cannot be larger than 226 226 the variations of depth. 227 It provides a better approximation of the \citet{ Gaspar1990} formulation while being much less227 It provides a better approximation of the \citet{gaspar.gregoris.ea_JGR90} formulation while being much less 228 228 time consuming. 229 229 In particular, it allows the length scale to be limited not only by the distance to the surface or … … 258 258 In the \np{nn\_mxl}\forcode{ = 2} case, the dissipation and mixing length scales take the same value: 259 259 $ l_k= l_\epsilon = \min \left(\ l_{up} \;,\; l_{dwn}\ \right)$, while in the \np{nn\_mxl}\forcode{ = 3} case, 260 the dissipation and mixing turbulent length scales are give as in \citet{ Gaspar1990}:260 the dissipation and mixing turbulent length scales are give as in \citet{gaspar.gregoris.ea_JGR90}: 261 261 \[ 262 262 % \label{eq:tke_mxl_gaspar} … … 270 270 Usually the surface scale is given by $l_o = \kappa \,z_o$ where $\kappa = 0.4$ is von Karman's constant and 271 271 $z_o$ the roughness parameter of the surface. 272 Assuming $z_o=0.1$~m \citep{ Craig_Banner_JPO94} leads to a 0.04~m, the default value of \np{rn\_mxl0}.272 Assuming $z_o=0.1$~m \citep{craig.banner_JPO94} leads to a 0.04~m, the default value of \np{rn\_mxl0}. 273 273 In the ocean interior a minimum length scale is set to recover the molecular viscosity when 274 274 $\bar{e}$ reach its minimum value ($1.10^{-6}= C_k\, l_{min} \,\sqrt{\bar{e}_{min}}$ ). … … 277 277 %-----------------------------------------------------------------------% 278 278 279 Following \citet{ Mellor_Blumberg_JPO04}, the TKE turbulence closure model has been modified to279 Following \citet{mellor.blumberg_JPO04}, the TKE turbulence closure model has been modified to 280 280 include the effect of surface wave breaking energetics. 281 281 This results in a reduction of summertime surface temperature when the mixed layer is relatively shallow. 282 The \citet{ Mellor_Blumberg_JPO04} modifications acts on surface length scale and TKE values and282 The \citet{mellor.blumberg_JPO04} modifications acts on surface length scale and TKE values and 283 283 air-sea drag coefficient. 284 284 The latter concerns the bulk formulea and is not discussed here. 285 285 286 Following \citet{ Craig_Banner_JPO94}, the boundary condition on surface TKE value is :286 Following \citet{craig.banner_JPO94}, the boundary condition on surface TKE value is : 287 287 \begin{equation} 288 288 \label{eq:ZDF_Esbc} 289 289 \bar{e}_o = \frac{1}{2}\,\left( 15.8\,\alpha_{CB} \right)^{2/3} \,\frac{|\tau|}{\rho_o} 290 290 \end{equation} 291 where $\alpha_{CB}$ is the \citet{ Craig_Banner_JPO94} constant of proportionality which depends on the ''wave age'',292 ranging from 57 for mature waves to 146 for younger waves \citep{ Mellor_Blumberg_JPO04}.291 where $\alpha_{CB}$ is the \citet{craig.banner_JPO94} constant of proportionality which depends on the ''wave age'', 292 ranging from 57 for mature waves to 146 for younger waves \citep{mellor.blumberg_JPO04}. 293 293 The boundary condition on the turbulent length scale follows the Charnock's relation: 294 294 \begin{equation} … … 297 297 \end{equation} 298 298 where $\kappa=0.40$ is the von Karman constant, and $\beta$ is the Charnock's constant. 299 \citet{ Mellor_Blumberg_JPO04} suggest $\beta = 2.10^{5}$ the value chosen by300 \citet{ Stacey_JPO99} citing observation evidence, and299 \citet{mellor.blumberg_JPO04} suggest $\beta = 2.10^{5}$ the value chosen by 300 \citet{stacey_JPO99} citing observation evidence, and 301 301 $\alpha_{CB} = 100$ the Craig and Banner's value. 302 302 As the surface boundary condition on TKE is prescribed through $\bar{e}_o = e_{bb} |\tau| / \rho_o$, … … 315 315 Although LC have nothing to do with convection, the circulation pattern is rather similar to 316 316 so-called convective rolls in the atmospheric boundary layer. 317 The detailed physics behind LC is described in, for example, \citet{ Craik_Leibovich_JFM76}.317 The detailed physics behind LC is described in, for example, \citet{craik.leibovich_JFM76}. 318 318 The prevailing explanation is that LC arise from a nonlinear interaction between the Stokes drift and 319 319 wind drift currents. 320 320 321 321 Here we introduced in the TKE turbulent closure the simple parameterization of Langmuir circulations proposed by 322 \citep{ Axell_JGR02} for a $k-\epsilon$ turbulent closure.322 \citep{axell_JGR02} for a $k-\epsilon$ turbulent closure. 323 323 The parameterization, tuned against large-eddy simulation, includes the whole effect of LC in 324 324 an extra source terms of TKE, $P_{LC}$. … … 326 326 \forcode{.true.} in the namtke namelist. 327 327 328 By making an analogy with the characteristic convective velocity scale (\eg, \citet{ D'Alessio_al_JPO98}),328 By making an analogy with the characteristic convective velocity scale (\eg, \citet{dalessio.abdella.ea_JPO98}), 329 329 $P_{LC}$ is assumed to be : 330 330 \[ … … 334 334 With no information about the wave field, $w_{LC}$ is assumed to be proportional to 335 335 the Stokes drift $u_s = 0.377\,\,|\tau|^{1/2}$, where $|\tau|$ is the surface wind stress module 336 \footnote{Following \citet{ Li_Garrett_JMR93}, the surface Stoke drift velocity may be expressed as336 \footnote{Following \citet{li.garrett_JMR93}, the surface Stoke drift velocity may be expressed as 337 337 $u_s = 0.016 \,|U_{10m}|$. 338 338 Assuming an air density of $\rho_a=1.22 \,Kg/m^3$ and a drag coefficient of … … 350 350 \end{cases} 351 351 \] 352 where $c_{LC} = 0.15$ has been chosen by \citep{ Axell_JGR02} as a good compromise to fit LES data.352 where $c_{LC} = 0.15$ has been chosen by \citep{axell_JGR02} as a good compromise to fit LES data. 353 353 The chosen value yields maximum vertical velocities $w_{LC}$ of the order of a few centimeters per second. 354 354 The value of $c_{LC}$ is set through the \np{rn\_lc} namelist parameter, 355 having in mind that it should stay between 0.15 and 0.54 \citep{ Axell_JGR02}.355 having in mind that it should stay between 0.15 and 0.54 \citep{axell_JGR02}. 356 356 357 357 The $H_{LC}$ is estimated in a similar way as the turbulent length scale of TKE equations: … … 368 368 produce mixed-layer depths that are too shallow during summer months and windy conditions. 369 369 This bias is particularly acute over the Southern Ocean. 370 To overcome this systematic bias, an ad hoc parameterization is introduced into the TKE scheme \cite{ Rodgers_2014}.370 To overcome this systematic bias, an ad hoc parameterization is introduced into the TKE scheme \cite{rodgers.aumont.ea_B14}. 371 371 The parameterization is an empirical one, \ie not derived from theoretical considerations, 372 372 but rather is meant to account for observed processes that affect the density structure of … … 427 427 (first line in \autoref{eq:PE_zdf}). 428 428 To do so a special care have to be taken for both the time and space discretization of 429 the TKE equation \citep{ Burchard_OM02,Marsaleix_al_OM08}.429 the TKE equation \citep{burchard_OM02,marsaleix.auclair.ea_OM08}. 430 430 431 431 Let us first address the time stepping issue. \autoref{fig:TKE_time_scheme} shows how … … 524 524 The Generic Length Scale (GLS) scheme is a turbulent closure scheme based on two prognostic equations: 525 525 one for the turbulent kinetic energy $\bar {e}$, and another for the generic length scale, 526 $\psi$ \citep{ Umlauf_Burchard_JMS03, Umlauf_Burchard_CSR05}.526 $\psi$ \citep{umlauf.burchard_JMR03, umlauf.burchard_CSR05}. 527 527 This later variable is defined as: $\psi = {C_{0\mu}}^{p} \ {\bar{e}}^{m} \ l^{n}$, 528 528 where the triplet $(p, m, n)$ value given in Tab.\autoref{tab:GLS} allows to recover a number of 529 well-known turbulent closures ($k$-$kl$ \citep{ Mellor_Yamada_1982}, $k$-$\epsilon$ \citep{Rodi_1987},530 $k$-$\omega$ \citep{ Wilcox_1988} among others \citep{Umlauf_Burchard_JMS03,Kantha_Carniel_CSR05}).529 well-known turbulent closures ($k$-$kl$ \citep{mellor.yamada_RG82}, $k$-$\epsilon$ \citep{rodi_JGR87}, 530 $k$-$\omega$ \citep{wilcox_AJ88} among others \citep{umlauf.burchard_JMR03,kantha.carniel_JMR03}). 531 531 The GLS scheme is given by the following set of equations: 532 532 \begin{equation} … … 577 577 \begin{tabular}{ccccc} 578 578 & $k-kl$ & $k-\epsilon$ & $k-\omega$ & generic \\ 579 % & \citep{ Mellor_Yamada_1982} & \citep{Rodi_1987} & \citep{Wilcox_1988} & \\579 % & \citep{mellor.yamada_RG82} & \citep{rodi_JGR87} & \citep{wilcox_AJ88} & \\ 580 580 \hline 581 581 \hline … … 604 604 the mixing length towards $K z_b$ ($K$: Kappa and $z_b$: rugosity length) value near physical boundaries 605 605 (logarithmic boundary layer law). 606 $C_{\mu}$ and $C_{\mu'}$ are calculated from stability function proposed by \citet{ Galperin_al_JAS88},607 or by \citet{ Kantha_Clayson_1994} or one of the two functions suggested by \citet{Canuto_2001}606 $C_{\mu}$ and $C_{\mu'}$ are calculated from stability function proposed by \citet{galperin.kantha.ea_JAS88}, 607 or by \citet{kantha.clayson_JGR94} or one of the two functions suggested by \citet{canuto.howard.ea_JPO01} 608 608 (\np{nn\_stab\_func}\forcode{ = 0..3}, resp.). 609 609 The value of $C_{0\mu}$ depends of the choice of the stability function. … … 612 612 Neumann condition through \np{nn\_tkebc\_surf} and \np{nn\_tkebc\_bot}, resp. 613 613 As for TKE closure, the wave effect on the mixing is considered when 614 \np{ln\_crban}\forcode{ = .true.} \citep{ Craig_Banner_JPO94, Mellor_Blumberg_JPO04}.614 \np{ln\_crban}\forcode{ = .true.} \citep{craig.banner_JPO94, mellor.blumberg_JPO04}. 615 615 The \np{rn\_crban} namelist parameter is $\alpha_{CB}$ in \autoref{eq:ZDF_Esbc} and 616 616 \np{rn\_charn} provides the value of $\beta$ in \autoref{eq:ZDF_Lsbc}. … … 619 619 almost all authors apply a clipping of the length scale as an \textit{ad hoc} remedy. 620 620 With this clipping, the maximum permissible length scale is determined by $l_{max} = c_{lim} \sqrt{2\bar{e}}/ N$. 621 A value of $c_{lim} = 0.53$ is often used \citep{ Galperin_al_JAS88}.622 \cite{ Umlauf_Burchard_CSR05} show that the value of the clipping factor is of crucial importance for621 A value of $c_{lim} = 0.53$ is often used \citep{galperin.kantha.ea_JAS88}. 622 \cite{umlauf.burchard_CSR05} show that the value of the clipping factor is of crucial importance for 623 623 the entrainment depth predicted in stably stratified situations, 624 624 and that its value has to be chosen in accordance with the algebraic model for the turbulent fluxes. … … 627 627 628 628 The time and space discretization of the GLS equations follows the same energetic consideration as for 629 the TKE case described in \autoref{subsec:ZDF_tke_ene} \citep{ Burchard_OM02}.630 Examples of performance of the 4 turbulent closure scheme can be found in \citet{ Warner_al_OM05}.629 the TKE case described in \autoref{subsec:ZDF_tke_ene} \citep{burchard_OM02}. 630 Examples of performance of the 4 turbulent closure scheme can be found in \citet{warner.sherwood.ea_OM05}. 631 631 632 632 % ------------------------------------------------------------------------------------------------------------- … … 700 700 the water column, but only until the density structure becomes neutrally stable 701 701 (\ie until the mixed portion of the water column has \textit{exactly} the density of the water just below) 702 \citep{ Madec_al_JPO91}.702 \citep{madec.delecluse.ea_JPO91}. 703 703 The associated algorithm is an iterative process used in the following way (\autoref{fig:npc}): 704 704 starting from the top of the ocean, the first instability is found. … … 718 718 the algorithm used in \NEMO converges for any profile in a number of iterations which is less than 719 719 the number of vertical levels. 720 This property is of paramount importance as pointed out by \citet{ Killworth1989}:720 This property is of paramount importance as pointed out by \citet{killworth_iprc89}: 721 721 it avoids the existence of permanent and unrealistic static instabilities at the sea surface. 722 722 This non-penetrative convective algorithm has been proved successful in studies of the deep water formation in 723 the north-western Mediterranean Sea \citep{ Madec_al_JPO91, Madec_al_DAO91, Madec_Crepon_Bk91}.723 the north-western Mediterranean Sea \citep{madec.delecluse.ea_JPO91, madec.chartier.ea_DAO91, madec.crepon_iprc91}. 724 724 725 725 The current implementation has been modified in order to deal with any non linear equation of seawater … … 748 748 In this case, the vertical eddy mixing coefficients are assigned very large values 749 749 (a typical value is $10\;m^2s^{-1})$ in regions where the stratification is unstable 750 (\ie when $N^2$ the Brunt-Vais\"{a}l\"{a} frequency is negative) \citep{ Lazar_PhD97, Lazar_al_JPO99}.750 (\ie when $N^2$ the Brunt-Vais\"{a}l\"{a} frequency is negative) \citep{lazar_phd97, lazar.madec.ea_JPO99}. 751 751 This is done either on tracers only (\np{nn\_evdm}\forcode{ = 0}) or 752 752 on both momentum and tracers (\np{nn\_evdm}\forcode{ = 1}). … … 764 764 Note that the stability test is performed on both \textit{before} and \textit{now} values of $N^2$. 765 765 This removes a potential source of divergence of odd and even time step in 766 a leapfrog environment \citep{ Leclair_PhD2010} (see \autoref{sec:STP_mLF}).766 a leapfrog environment \citep{leclair_phd10} (see \autoref{sec:STP_mLF}). 767 767 768 768 % ------------------------------------------------------------------------------------------------------------- … … 807 807 The former condition leads to salt fingering and the latter to diffusive convection. 808 808 Double-diffusive phenomena contribute to diapycnal mixing in extensive regions of the ocean. 809 \citet{ Merryfield1999} include a parameterisation of such phenomena in a global ocean model and show that809 \citet{merryfield.holloway.ea_JPO99} include a parameterisation of such phenomena in a global ocean model and show that 810 810 it leads to relatively minor changes in circulation but exerts significant regional influences on 811 811 temperature and salinity. … … 842 842 \caption{ 843 843 \protect\label{fig:zdfddm} 844 From \citet{ Merryfield1999} :844 From \citet{merryfield.holloway.ea_JPO99} : 845 845 (a) Diapycnal diffusivities $A_f^{vT}$ and $A_f^{vS}$ for temperature and salt in regions of salt fingering. 846 846 Heavy curves denote $A^{\ast v} = 10^{-3}~m^2.s^{-1}$ and thin curves $A^{\ast v} = 10^{-4}~m^2.s^{-1}$; … … 855 855 856 856 The factor 0.7 in \autoref{eq:zdfddm_f_T} reflects the measured ratio $\alpha F_T /\beta F_S \approx 0.7$ of 857 buoyancy flux of heat to buoyancy flux of salt (\eg, \citet{ McDougall_Taylor_JMR84}).858 Following \citet{ Merryfield1999}, we adopt $R_c = 1.6$, $n = 6$, and $A^{\ast v} = 10^{-4}~m^2.s^{-1}$.857 buoyancy flux of heat to buoyancy flux of salt (\eg, \citet{mcdougall.taylor_JMR84}). 858 Following \citet{merryfield.holloway.ea_JPO99}, we adopt $R_c = 1.6$, $n = 6$, and $A^{\ast v} = 10^{-4}~m^2.s^{-1}$. 859 859 860 860 To represent mixing of S and T by diffusive layering, the diapycnal diffusivities suggested by … … 963 963 This coefficient is generally estimated by setting a typical decay time $\tau$ in the deep ocean, 964 964 and setting $r = H / \tau$, where $H$ is the ocean depth. 965 Commonly accepted values of $\tau$ are of the order of 100 to 200 days \citep{ Weatherly_JMR84}.965 Commonly accepted values of $\tau$ are of the order of 100 to 200 days \citep{weatherly_JMR84}. 966 966 A value $\tau^{-1} = 10^{-7}$~s$^{-1}$ equivalent to 115 days, is usually used in quasi-geostrophic models. 967 967 One may consider the linear friction as an approximation of quadratic friction, $r \approx 2\;C_D\;U_{av}$ 968 (\citet{ Gill1982}, Eq. 9.6.6).968 (\citet{gill_bk82}, Eq. 9.6.6). 969 969 For example, with a drag coefficient $C_D = 0.002$, a typical speed of tidal currents of $U_{av} =0.1$~m\;s$^{-1}$, 970 970 and assuming an ocean depth $H = 4000$~m, the resulting friction coefficient is $r = 4\;10^{-4}$~m\;s$^{-1}$. … … 1005 1005 internal waves breaking and other short time scale currents. 1006 1006 A typical value of the drag coefficient is $C_D = 10^{-3} $. 1007 As an example, the CME experiment \citep{ Treguier_JGR92} uses $C_D = 10^{-3}$ and1008 $e_b = 2.5\;10^{-3}$m$^2$\;s$^{-2}$, while the FRAM experiment \citep{ Killworth1992} uses $C_D = 1.4\;10^{-3}$ and1007 As an example, the CME experiment \citep{treguier_JGR92} uses $C_D = 10^{-3}$ and 1008 $e_b = 2.5\;10^{-3}$m$^2$\;s$^{-2}$, while the FRAM experiment \citep{killworth_JPO92} uses $C_D = 1.4\;10^{-3}$ and 1009 1009 $e_b =2.5\;\;10^{-3}$m$^2$\;s$^{-2}$. 1010 1010 The CME choices have been set as default values (\np{rn\_bfri2} and \np{rn\_bfeb2} namelist parameters). … … 1235 1235 Options are defined through the \ngn{namzdf\_tmx} namelist variables. 1236 1236 The parameterization of tidal mixing follows the general formulation for the vertical eddy diffusivity proposed by 1237 \citet{ St_Laurent_al_GRL02} and first introduced in an OGCM by \citep{Simmons_al_OM04}.1237 \citet{st-laurent.simmons.ea_GRL02} and first introduced in an OGCM by \citep{simmons.jayne.ea_OM04}. 1238 1238 In this formulation an additional vertical diffusivity resulting from internal tide breaking, 1239 1239 $A^{vT}_{tides}$ is expressed as a function of $E(x,y)$, … … 1252 1252 with the remaining $1-q$ radiating away as low mode internal waves and 1253 1253 contributing to the background internal wave field. 1254 A value of $q=1/3$ is typically used \citet{ St_Laurent_al_GRL02}.1254 A value of $q=1/3$ is typically used \citet{st-laurent.simmons.ea_GRL02}. 1255 1255 The vertical structure function $F(z)$ models the distribution of the turbulent mixing in the vertical. 1256 1256 It is implemented as a simple exponential decaying upward away from the bottom, 1257 1257 with a vertical scale of $h_o$ (\np{rn\_htmx} namelist parameter, 1258 with a typical value of $500\,m$) \citep{ St_Laurent_Nash_DSR04},1258 with a typical value of $500\,m$) \citep{st-laurent.nash_DSR04}, 1259 1259 \[ 1260 1260 % \label{eq:Fz} … … 1274 1274 the unrepresented internal waves induced by the tidal flow over rough topography in a stratified ocean. 1275 1275 In the current version of \NEMO, the map is built from the output of 1276 the barotropic global ocean tide model MOG2D-G \citep{ Carrere_Lyard_GRL03}.1276 the barotropic global ocean tide model MOG2D-G \citep{carrere.lyard_GRL03}. 1277 1277 This model provides the dissipation associated with internal wave energy for the M2 and K1 tides component 1278 1278 (\autoref{fig:ZDF_M2_K1_tmx}). … … 1280 1280 The internal wave energy is thus : $E(x, y) = 1.25 E_{M2} + E_{K1}$. 1281 1281 Its global mean value is $1.1$ TW, 1282 in agreement with independent estimates \citep{ Egbert_Ray_Nat00, Egbert_Ray_JGR01}.1282 in agreement with independent estimates \citep{egbert.ray_N00, egbert.ray_JGR01}. 1283 1283 1284 1284 %>>>>>>>>>>>>>>>>>>>>>>>>>>>> … … 1288 1288 \caption{ 1289 1289 \protect\label{fig:ZDF_M2_K1_tmx} 1290 (a) M2 and (b) K1 internal wave drag energy from \citet{ Carrere_Lyard_GRL03} ($W/m^2$).1290 (a) M2 and (b) K1 internal wave drag energy from \citet{carrere.lyard_GRL03} ($W/m^2$). 1291 1291 } 1292 1292 \end{center} … … 1306 1306 1307 1307 When \np{ln\_tmx\_itf}\forcode{ = .true.}, the two key parameters $q$ and $F(z)$ are adjusted following 1308 the parameterisation developed by \citet{ Koch-Larrouy_al_GRL07}:1308 the parameterisation developed by \citet{koch-larrouy.madec.ea_GRL07}: 1309 1309 1310 1310 First, the Indonesian archipelago is a complex geographic region with a series of … … 1318 1318 Second, the vertical structure function, $F(z)$, is no more associated with a bottom intensification of the mixing, 1319 1319 but with a maximum of energy available within the thermocline. 1320 \citet{ Koch-Larrouy_al_GRL07} have suggested that the vertical distribution of1320 \citet{koch-larrouy.madec.ea_GRL07} have suggested that the vertical distribution of 1321 1321 the energy dissipation proportional to $N^2$ below the core of the thermocline and to $N$ above. 1322 1322 The resulting $F(z)$ is: … … 1335 1335 Introduced in a regional OGCM, the parameterization improves the water mass characteristics in 1336 1336 the different Indonesian seas, suggesting that the horizontal and vertical distributions of 1337 the mixing are adequately prescribed \citep{ Koch-Larrouy_al_GRL07, Koch-Larrouy_al_OD08a, Koch-Larrouy_al_OD08b}.1337 the mixing are adequately prescribed \citep{koch-larrouy.madec.ea_GRL07, koch-larrouy.madec.ea_OD08*a, koch-larrouy.madec.ea_OD08*b}. 1338 1338 Note also that such a parameterisation has a significant impact on the behaviour of 1339 global coupled GCMs \citep{ Koch-Larrouy_al_CD10}.1339 global coupled GCMs \citep{koch-larrouy.lengaigne.ea_CD10}. 1340 1340 1341 1341 % ================================================================ … … 1351 1351 1352 1352 The parameterization of mixing induced by breaking internal waves is a generalization of 1353 the approach originally proposed by \citet{ St_Laurent_al_GRL02}.1353 the approach originally proposed by \citet{st-laurent.simmons.ea_GRL02}. 1354 1354 A three-dimensional field of internal wave energy dissipation $\epsilon(x,y,z)$ is first constructed, 1355 1355 and the resulting diffusivity is obtained as … … 1361 1361 the energy available for mixing. 1362 1362 If the \np{ln\_mevar} namelist parameter is set to false, the mixing efficiency is taken as constant and 1363 equal to 1/6 \citep{ Osborn_JPO80}.1363 equal to 1/6 \citep{osborn_JPO80}. 1364 1364 In the opposite (recommended) case, $R_f$ is instead a function of 1365 1365 the turbulence intensity parameter $Re_b = \frac{ \epsilon}{\nu \, N^2}$, 1366 with $\nu$ the molecular viscosity of seawater, following the model of \cite{ Bouffard_Boegman_DAO2013} and1367 the implementation of \cite{de _lavergne_JPO2016_efficiency}.1366 with $\nu$ the molecular viscosity of seawater, following the model of \cite{bouffard.boegman_DAO13} and 1367 the implementation of \cite{de-lavergne.madec.ea_JPO16}. 1368 1368 Note that $A^{vT}_{wave}$ is bounded by $10^{-2}\,m^2/s$, a limit that is often reached when 1369 1369 the mixing efficiency is constant. … … 1371 1371 In addition to the mixing efficiency, the ratio of salt to heat diffusivities can chosen to vary 1372 1372 as a function of $Re_b$ by setting the \np{ln\_tsdiff} parameter to true, a recommended choice. 1373 This parameterization of differential mixing, due to \cite{ Jackson_Rehmann_JPO2014},1374 is implemented as in \cite{de _lavergne_JPO2016_efficiency}.1373 This parameterization of differential mixing, due to \cite{jackson.rehmann_JPO14}, 1374 is implemented as in \cite{de-lavergne.madec.ea_JPO16}. 1375 1375 1376 1376 The three-dimensional distribution of the energy available for mixing, $\epsilon(i,j,k)$, … … 1395 1395 $h_{cri}$ is related to the large-scale topography of the ocean (etopo2) and 1396 1396 $h_{bot}$ is a function of the energy flux $E_{bot}$, the characteristic horizontal scale of 1397 the abyssal hill topography \citep{ Goff_JGR2010} and the latitude.1397 the abyssal hill topography \citep{goff_JGR10} and the latitude. 1398 1398 1399 1399 % ================================================================
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