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Changeset 10419 for NEMO/branches/2018/dev_r10164_HPC09_ESIWACE_PREP_MERGE/doc/latex/NEMO/subfiles/chap_ZDF.tex – NEMO

Ignore:
Timestamp:
2018-12-19T20:46:30+01:00 (5 years ago)
Author:
smasson
Message:

dev_r10164_HPC09_ESIWACE_PREP_MERGE: merge with trunk@10418, see #2133

Location:
NEMO/branches/2018/dev_r10164_HPC09_ESIWACE_PREP_MERGE/doc/latex
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4 edited

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  • NEMO/branches/2018/dev_r10164_HPC09_ESIWACE_PREP_MERGE/doc/latex/NEMO/subfiles/chap_ZDF.tex

    r10368 r10419  
    1 \documentclass[../tex_main/NEMO_manual]{subfiles} 
     1\documentclass[../main/NEMO_manual]{subfiles} 
     2 
    23\begin{document} 
    34% ================================================================ 
     
    67\chapter{Vertical Ocean Physics (ZDF)} 
    78\label{chap:ZDF} 
     9 
    810\minitoc 
    911 
    1012%gm% Add here a small introduction to ZDF and naming of the different physics (similar to what have been written for TRA and DYN. 
    1113 
    12  
    1314\newpage 
    14 $\ $\newline    % force a new ligne 
    15  
    1615 
    1716% ================================================================ 
     
    6059It is recommended that this option is only used in process studies, not in basin scale simulations. 
    6160Typical values used in this case are: 
    62 \begin{align*}  
    63 A_u^{vm} = A_v^{vm} &= 1.2\ 10^{-4}~m^2.s^{-1}  \\ 
    64 A^{vT} = A^{vS} &= 1.2\ 10^{-5}~m^2.s^{-1} 
     61\begin{align*} 
     62  A_u^{vm} = A_v^{vm} &= 1.2\ 10^{-4}~m^2.s^{-1}   \\ 
     63  A^{vT} = A^{vS} &= 1.2\ 10^{-5}~m^2.s^{-1} 
    6564\end{align*} 
    6665 
     
    6968that is $\sim10^{-6}~m^2.s^{-1}$ for momentum, $\sim10^{-7}~m^2.s^{-1}$ for temperature and 
    7069$\sim10^{-9}~m^2.s^{-1}$ for salinity. 
    71  
    7270 
    7371% ------------------------------------------------------------------------------------------------------------- 
     
    9088($i.e.$ the ratio of stratification to vertical shear). 
    9189Following \citet{Pacanowski_Philander_JPO81}, the following formulation has been implemented: 
    92 \begin{equation} \label{eq:zdfric} 
    93    \left\{      \begin{aligned} 
    94          A^{vT} &= \frac {A_{ric}^{vT}}{\left( 1+a \; Ri \right)^n} + A_b^{vT}       \\ 
    95          A^{vm} &= \frac{A^{vT}        }{\left( 1+ a \;Ri  \right)   } + A_b^{vm} 
    96    \end{aligned}    \right. 
    97 \end{equation} 
     90\[ 
     91  % \label{eq:zdfric} 
     92  \left\{ 
     93    \begin{aligned} 
     94      A^{vT} &= \frac {A_{ric}^{vT}}{\left( 1+a \; Ri \right)^n} + A_b^{vT}       \\ 
     95      A^{vm} &= \frac{A^{vT}        }{\left( 1+ a \;Ri  \right)   } + A_b^{vm} 
     96    \end{aligned} 
     97  \right. 
     98\] 
    9899where $Ri = N^2 / \left(\partial_z \textbf{U}_h \right)^2$ is the local Richardson number, 
    99100$N$ is the local Brunt-Vais\"{a}l\"{a} frequency (see \autoref{subsec:TRA_bn2}),  
     
    111112 
    112113This depth is assumed proportional to the "depth of frictional influence" that is limited by rotation: 
    113 \begin{equation} 
    114 h_{e} = Ek \frac {u^{*}} {f_{0}} 
    115 \end{equation} 
     114\[ 
     115  h_{e} = Ek \frac {u^{*}} {f_{0}} 
     116\] 
    116117where, $Ek$ is an empirical parameter, $u^{*}$ is the friction velocity and $f_{0}$ is the Coriolis parameter. 
    117118 
    118119In this similarity height relationship, the turbulent friction velocity: 
    119 \begin{equation} 
    120 u^{*} = \sqrt \frac {|\tau|} {\rho_o} 
    121 \end{equation} 
     120\[ 
     121  u^{*} = \sqrt \frac {|\tau|} {\rho_o} 
     122\] 
    122123is computed from the wind stress vector $|\tau|$ and the reference density $ \rho_o$. 
    123124The final $h_{e}$ is further constrained by the adjustable bounds \np{rn\_mldmin} and \np{rn\_mldmax}. 
     
    146147The time evolution of $\bar{e}$ is the result of the production of $\bar{e}$ through vertical shear, 
    147148its destruction through stratification, its vertical diffusion, and its dissipation of \citet{Kolmogorov1942} type: 
    148 \begin{equation} \label{eq:zdftke_e} 
    149 \frac{\partial \bar{e}}{\partial t} =  
    150 \frac{K_m}{{e_3}^2 }\;\left[ {\left( {\frac{\partial u}{\partial k}} \right)^2 
    151                     +\left( {\frac{\partial v}{\partial k}} \right)^2} \right] 
    152 -K_\rho\,N^2 
    153 +\frac{1}{e_3} \;\frac{\partial }{\partial k}\left[ {\frac{A^{vm}}{e_3 } 
    154             \;\frac{\partial \bar{e}}{\partial k}} \right] 
    155 - c_\epsilon \;\frac{\bar {e}^{3/2}}{l_\epsilon } 
     149\begin{equation} 
     150  \label{eq:zdftke_e} 
     151  \frac{\partial \bar{e}}{\partial t} = 
     152  \frac{K_m}{{e_3}^2 }\;\left[ {\left( {\frac{\partial u}{\partial k}} \right)^2 
     153      +\left( {\frac{\partial v}{\partial k}} \right)^2} \right] 
     154  -K_\rho\,N^2 
     155  +\frac{1}{e_3}  \;\frac{\partial }{\partial k}\left[ {\frac{A^{vm}}{e_3 } 
     156      \;\frac{\partial \bar{e}}{\partial k}} \right] 
     157  - c_\epsilon \;\frac{\bar {e}^{3/2}}{l_\epsilon } 
    156158\end{equation} 
    157 \begin{equation} \label{eq:zdftke_kz} 
    158    \begin{split} 
    159          K_m &= C_k\  l_k\  \sqrt {\bar{e}\; }     \\ 
    160          K_\rho &= A^{vm} / P_{rt} 
    161    \end{split} 
    162 \end{equation} 
     159\[ 
     160  % \label{eq:zdftke_kz} 
     161  \begin{split} 
     162    K_m &= C_k\  l_k\  \sqrt {\bar{e}\; }    \\ 
     163    K_\rho &= A^{vm} / P_{rt} 
     164  \end{split} 
     165\] 
    163166where $N$ is the local Brunt-Vais\"{a}l\"{a} frequency (see \autoref{subsec:TRA_bn2}),  
    164167$l_{\epsilon }$ and $l_{\kappa }$ are the dissipation and mixing length scales,  
     
    168171They are set through namelist parameters \np{nn\_ediff} and \np{nn\_ediss}. 
    169172$P_{rt}$ can be set to unity or, following \citet{Blanke1993}, be a function of the local Richardson number, $R_i$: 
    170 \begin{align*} \label{eq:prt} 
    171 P_{rt} = \begin{cases} 
    172                     \ \ \ 1 &      \text{if $\ R_i \leq 0.2$}  \\ 
    173                     5\,R_i &      \text{if $\ 0.2 \leq R_i \leq 2$}  \\ 
    174                     \ \ 10 &      \text{if $\ 2 \leq R_i$}  
    175             \end{cases} 
     173\begin{align*} 
     174  % \label{eq:prt} 
     175  P_{rt} = 
     176  \begin{cases} 
     177    \ \ \ 1 &      \text{if $\ R_i \leq 0.2$}   \\ 
     178    5\,R_i &      \text{if $\ 0.2 \leq R_i \leq 2$}   \\ 
     179    \ \ 10 &      \text{if $\ 2 \leq R_i$} 
     180  \end{cases} 
    176181\end{align*} 
    177182Options are defined through the  \ngn{namzdfy\_tke} namelist variables. 
     
    195200 
    196201\subsubsection{Turbulent length scale} 
     202 
    197203For computational efficiency, the original formulation of the turbulent length scales proposed by 
    198204\citet{Gaspar1990} has been simplified. 
    199205Four formulations are proposed, the choice of which is controlled by the \np{nn\_mxl} namelist parameter. 
    200206The first two are based on the following first order approximation \citep{Blanke1993}: 
    201 \begin{equation} \label{eq:tke_mxl0_1} 
    202 l_k = l_\epsilon = \sqrt {2 \bar{e}\; } / N 
     207\begin{equation} 
     208  \label{eq:tke_mxl0_1} 
     209  l_k = l_\epsilon = \sqrt {2 \bar{e}\; } / N 
    203210\end{equation} 
    204211which is valid in a stable stratified region with constant values of the Brunt-Vais\"{a}l\"{a} frequency. 
     
    211218which add an extra assumption concerning the vertical gradient of the computed length scale. 
    212219So, the length scales are first evaluated as in \autoref{eq:tke_mxl0_1} and then bounded such that: 
    213 \begin{equation} \label{eq:tke_mxl_constraint} 
    214 \frac{1}{e_3 }\left| {\frac{\partial l}{\partial k}} \right| \leq 1 
    215 \qquad \text{with }\  l =  l_k = l_\epsilon 
     220\begin{equation} 
     221  \label{eq:tke_mxl_constraint} 
     222  \frac{1}{e_3 }\left| {\frac{\partial l}{\partial k}} \right| \leq 1 
     223  \qquad \text{with }\  l =  l_k = l_\epsilon 
    216224\end{equation} 
    217225\autoref{eq:tke_mxl_constraint} means that the vertical variations of the length scale cannot be larger than 
     
    227235(and note that here we use numerical indexing): 
    228236%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    229 \begin{figure}[!t] \begin{center} 
    230 \includegraphics[width=1.00\textwidth]{Fig_mixing_length} 
    231 \caption{ \protect\label{fig:mixing_length}  
    232 Illustration of the mixing length computation. } 
    233 \end{center}   
     237\begin{figure}[!t] 
     238  \begin{center} 
     239    \includegraphics[width=1.00\textwidth]{Fig_mixing_length} 
     240    \caption{ 
     241      \protect\label{fig:mixing_length} 
     242      Illustration of the mixing length computation. 
     243    } 
     244  \end{center} 
    234245\end{figure} 
    235246%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    236 \begin{equation} \label{eq:tke_mxl2} 
    237 \begin{aligned} 
    238  l_{up\ \ }^{(k)} &= \min \left(  l^{(k)} \ , \ l_{up}^{(k+1)} + e_{3t}^{(k)}\ \ \ \;  \right) 
     247\[ 
     248  % \label{eq:tke_mxl2} 
     249  \begin{aligned} 
     250    l_{up\ \ }^{(k)} &= \min \left(  l^{(k)} \ , \ l_{up}^{(k+1)} + e_{3t}^{(k)}\ \ \ \;  \right) 
    239251    \quad &\text{ from $k=1$ to $jpk$ }\ \\ 
    240  l_{dwn}^{(k)} &= \min \left(  l^{(k)} \ , \ l_{dwn}^{(k-1)} + e_{3t}^{(k-1)}  \right)    
     252    l_{dwn}^{(k)} &= \min \left(  l^{(k)} \ , \ l_{dwn}^{(k-1)} + e_{3t}^{(k-1)}  \right) 
    241253    \quad &\text{ from $k=jpk$ to $1$ }\ \\ 
    242 \end{aligned} 
    243 \end{equation} 
     254  \end{aligned} 
     255\] 
    244256where $l^{(k)}$ is computed using \autoref{eq:tke_mxl0_1}, $i.e.$ $l^{(k)} = \sqrt {2 {\bar e}^{(k)} / {N^2}^{(k)} }$. 
    245257 
     
    247259$ l_k=  l_\epsilon = \min \left(\ l_{up} \;,\;  l_{dwn}\ \right)$, while in the \np{nn\_mxl}\forcode{ = 3} case, 
    248260the dissipation and mixing turbulent length scales are give as in \citet{Gaspar1990}: 
    249 \begin{equation} \label{eq:tke_mxl_gaspar} 
    250 \begin{aligned} 
    251 & l_k          = \sqrt{\  l_{up} \ \ l_{dwn}\ }    \\ 
    252 & l_\epsilon = \min \left(\ l_{up} \;,\;  l_{dwn}\ \right)  
    253 \end{aligned} 
    254 \end{equation} 
     261\[ 
     262  % \label{eq:tke_mxl_gaspar} 
     263  \begin{aligned} 
     264    & l_k          = \sqrt{\  l_{up} \ \ l_{dwn}\ }   \\ 
     265    & l_\epsilon = \min \left(\ l_{up} \;,\;  l_{dwn}\ \right) 
     266  \end{aligned} 
     267\] 
    255268 
    256269At the ocean surface, a non zero length scale is set through the  \np{rn\_mxl0} namelist parameter. 
     
    261274$\bar{e}$ reach its minimum value ($1.10^{-6}= C_k\, l_{min} \,\sqrt{\bar{e}_{min}}$ ). 
    262275 
    263  
    264276\subsubsection{Surface wave breaking parameterization} 
    265277%-----------------------------------------------------------------------% 
     278 
    266279Following \citet{Mellor_Blumberg_JPO04}, the TKE turbulence closure model has been modified to 
    267280include the effect of surface wave breaking energetics. 
     
    272285 
    273286Following \citet{Craig_Banner_JPO94}, the boundary condition on surface TKE value is : 
    274 \begin{equation}  \label{eq:ZDF_Esbc} 
    275 \bar{e}_o = \frac{1}{2}\,\left(  15.8\,\alpha_{CB} \right)^{2/3} \,\frac{|\tau|}{\rho_o} 
     287\begin{equation} 
     288  \label{eq:ZDF_Esbc} 
     289  \bar{e}_o = \frac{1}{2}\,\left(  15.8\,\alpha_{CB} \right)^{2/3} \,\frac{|\tau|}{\rho_o} 
    276290\end{equation} 
    277291where $\alpha_{CB}$ is the \citet{Craig_Banner_JPO94} constant of proportionality which depends on the ''wave age'', 
    278292ranging from 57 for mature waves to 146 for younger waves \citep{Mellor_Blumberg_JPO04}.  
    279293The boundary condition on the turbulent length scale follows the Charnock's relation: 
    280 \begin{equation} \label{eq:ZDF_Lsbc} 
    281 l_o = \kappa \beta \,\frac{|\tau|}{g\,\rho_o} 
     294\begin{equation} 
     295  \label{eq:ZDF_Lsbc} 
     296  l_o = \kappa \beta \,\frac{|\tau|}{g\,\rho_o} 
    282297\end{equation} 
    283298where $\kappa=0.40$ is the von Karman constant, and $\beta$ is the Charnock's constant. 
     
    293308surface $\bar{e}$ value. 
    294309 
    295  
    296310\subsubsection{Langmuir cells} 
    297311%--------------------------------------% 
     312 
    298313Langmuir circulations (LC) can be described as ordered large-scale vertical motions in 
    299314the surface layer of the oceans. 
     
    313328By making an analogy with the characteristic convective velocity scale ($e.g.$, \citet{D'Alessio_al_JPO98}), 
    314329$P_{LC}$ is assumed to be :  
    315 \begin{equation} 
     330\[ 
    316331P_{LC}(z) = \frac{w_{LC}^3(z)}{H_{LC}} 
    317 \end{equation} 
     332\] 
    318333where $w_{LC}(z)$ is the vertical velocity profile of LC, and $H_{LC}$ is the LC depth. 
    319334With no information about the wave field, $w_{LC}$ is assumed to be proportional to  
     
    322337  $u_s =  0.016 \,|U_{10m}|$. 
    323338  Assuming an air density of $\rho_a=1.22 \,Kg/m^3$ and a drag coefficient of 
    324   $1.5~10^{-3}$ give the expression used of $u_s$ as a function of the module of surface stress}. 
     339  $1.5~10^{-3}$ give the expression used of $u_s$ as a function of the module of surface stress 
     340}. 
    325341For the vertical variation, $w_{LC}$ is assumed to be zero at the surface as well as at 
    326342a finite depth $H_{LC}$ (which is often close to the mixed layer depth), 
    327343and simply varies as a sine function in between (a first-order profile for the Langmuir cell structures).  
    328344The resulting expression for $w_{LC}$ is : 
    329 \begin{equation} 
    330 w_{LC}  = \begin{cases} 
    331                    c_{LC} \,u_s \,\sin(- \pi\,z / H_{LC} )    &      \text{if $-z \leq H_{LC}$}    \\ 
    332                    0                             &      \text{otherwise}  
    333                  \end{cases} 
    334 \end{equation} 
     345\[ 
     346  w_{LC}  = 
     347  \begin{cases} 
     348    c_{LC} \,u_s \,\sin(- \pi\,z / H_{LC} )    &      \text{if $-z \leq H_{LC}$}    \\ 
     349    0                             &      \text{otherwise} 
     350  \end{cases} 
     351\] 
    335352where $c_{LC} = 0.15$ has been chosen by \citep{Axell_JGR02} as a good compromise to fit LES data. 
    336353The chosen value yields maximum vertical velocities $w_{LC}$ of the order of a few centimeters per second. 
     
    341358$H_{LC}$ is depth to which a water parcel with kinetic energy due to Stoke drift can reach on its own by 
    342359converting its kinetic energy to potential energy, according to  
    343 \begin{equation} 
     360\[ 
    344361- \int_{-H_{LC}}^0 { N^2\;z  \;dz} = \frac{1}{2} u_s^2 
    345 \end{equation} 
    346  
     362\] 
    347363 
    348364\subsubsection{Mixing just below the mixed layer} 
     
    362378swell and waves is parameterized by \autoref{eq:ZDF_Esbc} the standard TKE surface boundary condition, 
    363379plus a depth depend one given by: 
    364 \begin{equation}  \label{eq:ZDF_Ehtau} 
    365 S = (1-f_i) \; f_r \; e_s \; e^{-z / h_\tau}  
     380\begin{equation} 
     381  \label{eq:ZDF_Ehtau} 
     382  S = (1-f_i) \; f_r \; e_s \; e^{-z / h_\tau} 
    366383\end{equation} 
    367384where $z$ is the depth, $e_s$ is TKE surface boundary condition, $f_r$ is the fraction of the surface TKE that 
     
    380397They will be removed in the next release.  
    381398 
    382  
    383  
    384399% from Burchard et al OM 2008 :  
    385400% the most critical process not reproduced by statistical turbulence models is the activity of  
     
    390405% (e.g. Mellor, 1989; Large et al., 1994; Meier, 2001; Axell, 2002; St. Laurent and Garrett, 2002). 
    391406 
    392  
    393  
    394407% ------------------------------------------------------------------------------------------------------------- 
    395408%        TKE discretization considerations 
     
    399412 
    400413%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    401 \begin{figure}[!t]   \begin{center} 
    402 \includegraphics[width=1.00\textwidth]{Fig_ZDF_TKE_time_scheme} 
    403 \caption{ \protect\label{fig:TKE_time_scheme}  
    404 Illustration of the TKE time integration and its links to the momentum and tracer time integration. } 
    405 \end{center}   
     414\begin{figure}[!t] 
     415  \begin{center} 
     416    \includegraphics[width=1.00\textwidth]{Fig_ZDF_TKE_time_scheme} 
     417    \caption{ 
     418      \protect\label{fig:TKE_time_scheme} 
     419      Illustration of the TKE time integration and its links to the momentum and tracer time integration. 
     420    } 
     421  \end{center}   
    406422\end{figure} 
    407423%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
     
    419435the vertical momentum diffusion is obtained by multiplying this quantity by $u^t$ and 
    420436summing the result vertically:    
    421 \begin{equation} \label{eq:energ1} 
    422 \begin{split} 
    423 \int_{-H}^{\eta}  u^t \,\partial_z &\left( {K_m}^t \,(\partial_z u)^{t+\rdt}  \right) \,dz   \\ 
    424 &= \Bigl[  u^t \,{K_m}^t \,(\partial_z u)^{t+\rdt} \Bigr]_{-H}^{\eta}           
    425  - \int_{-H}^{\eta}{ {K_m}^t \,\partial_z{u^t} \,\partial_z u^{t+\rdt} \,dz } 
    426 \end{split} 
     437\begin{equation} 
     438  \label{eq:energ1} 
     439  \begin{split} 
     440    \int_{-H}^{\eta}  u^t \,\partial_z &\left( {K_m}^t \,(\partial_z u)^{t+\rdt}  \right) \,dz   \\ 
     441    &= \Bigl[  u^t \,{K_m}^t \,(\partial_z u)^{t+\rdt} \Bigr]_{-H}^{\eta} 
     442    - \int_{-H}^{\eta}{ {K_m}^t \,\partial_z{u^t} \,\partial_z u^{t+\rdt} \,dz } 
     443  \end{split} 
    427444\end{equation} 
    428445Here, the vertical diffusion of momentum is discretized backward in time with a coefficient, $K_m$, 
     
    443460The rate of change of potential energy (in 1D for the demonstration) due vertical mixing is obtained by 
    444461multiplying vertical density diffusion tendency by $g\,z$ and and summing the result vertically: 
    445 \begin{equation} \label{eq:energ2} 
    446 \begin{split} 
    447 \int_{-H}^{\eta} g\,z\,\partial_z &\left( {K_\rho}^t \,(\partial_k \rho)^{t+\rdt}   \right) \,dz    \\ 
    448 &= \Bigl[  g\,z \,{K_\rho}^t \,(\partial_z \rho)^{t+\rdt} \Bigr]_{-H}^{\eta}   
    449    - \int_{-H}^{\eta}{ g \,{K_\rho}^t \,(\partial_k \rho)^{t+\rdt} } \,dz   \\ 
    450 &= - \Bigl[  z\,{K_\rho}^t \,(N^2)^{t+\rdt} \Bigr]_{-H}^{\eta} 
    451 + \int_{-H}^{\eta}{  \rho^{t+\rdt} \, {K_\rho}^t \,(N^2)^{t+\rdt} \,dz  } 
    452 \end{split} 
     462\begin{equation} 
     463  \label{eq:energ2} 
     464  \begin{split} 
     465    \int_{-H}^{\eta} g\,z\,\partial_z &\left( {K_\rho}^t \,(\partial_k \rho)^{t+\rdt}   \right) \,dz    \\ 
     466    &= \Bigl[  g\,z \,{K_\rho}^t \,(\partial_z \rho)^{t+\rdt} \Bigr]_{-H}^{\eta} 
     467    - \int_{-H}^{\eta}{ g \,{K_\rho}^t \,(\partial_k \rho)^{t+\rdt} } \,dz   \\ 
     468    &= - \Bigl[  z\,{K_\rho}^t \,(N^2)^{t+\rdt} \Bigr]_{-H}^{\eta} 
     469    + \int_{-H}^{\eta}{  \rho^{t+\rdt} \, {K_\rho}^t \,(N^2)^{t+\rdt} \,dz  } 
     470  \end{split} 
    453471\end{equation} 
    454472where we use $N^2 = -g \,\partial_k \rho / (e_3 \rho)$.  
     
    468486 
    469487The above energetic considerations leads to the following final discrete form for the TKE equation: 
    470 \begin{equation} \label{eq:zdftke_ene} 
    471 \begin{split} 
    472 \frac { (\bar{e})^t - (\bar{e})^{t-\rdt} } {\rdt}  \equiv   
    473 \Biggl\{ \Biggr. 
    474   &\overline{ \left( \left(\overline{K_m}^{\,i+1/2}\right)^{t-\rdt} \,\frac{\delta_{k+1/2}[u^{t+\rdt}]}{{e_3u}^{t+\rdt} }  
    475                                                                               \ \frac{\delta_{k+1/2}[u^ t         ]}{{e_3u}^ t          }  \right) }^{\,i} \\ 
    476 +&\overline{  \left( \left(\overline{K_m}^{\,j+1/2}\right)^{t-\rdt} \,\frac{\delta_{k+1/2}[v^{t+\rdt}]}{{e_3v}^{t+\rdt} }  
    477                                                                                \ \frac{\delta_{k+1/2}[v^ t         ]}{{e_3v}^ t          }  \right) }^{\,j}  
    478 \Biggr. \Biggr\}   \\ 
    479 % 
    480 - &{K_\rho}^{t-\rdt}\,{(N^2)^t}    \\ 
    481 % 
    482 +&\frac{1}{{e_3w}^{t+\rdt}}  \;\delta_{k+1/2} \left[   {K_m}^{t-\rdt} \,\frac{\delta_{k}[(\bar{e})^{t+\rdt}]} {{e_3w}^{t+\rdt}}   \right]   \\ 
    483 % 
    484 - &c_\epsilon \; \left( \frac{\sqrt{\bar {e}}}{l_\epsilon}\right)^{t-\rdt}\,(\bar {e})^{t+\rdt} 
    485 \end{split} 
     488\begin{equation} 
     489  \label{eq:zdftke_ene} 
     490  \begin{split} 
     491    \frac { (\bar{e})^t - (\bar{e})^{t-\rdt} } {\rdt}  \equiv 
     492    \Biggl\{ \Biggr. 
     493    &\overline{ \left( \left(\overline{K_m}^{\,i+1/2}\right)^{t-\rdt} \,\frac{\delta_{k+1/2}[u^{t+\rdt}]}{{e_3u}^{t+\rdt} } 
     494        \ \frac{\delta_{k+1/2}[u^ t         ]}{{e_3u}^ t          }  \right) }^{\,i} \\ 
     495    +&\overline{  \left( \left(\overline{K_m}^{\,j+1/2}\right)^{t-\rdt} \,\frac{\delta_{k+1/2}[v^{t+\rdt}]}{{e_3v}^{t+\rdt} } 
     496        \ \frac{\delta_{k+1/2}[v^ t         ]}{{e_3v}^ t          }  \right) }^{\,j} 
     497    \Biggr. \Biggr\}   \\ 
     498    % 
     499    - &{K_\rho}^{t-\rdt}\,{(N^2)^t}    \\ 
     500    % 
     501    +&\frac{1}{{e_3w}^{t+\rdt}}  \;\delta_{k+1/2} \left[   {K_m}^{t-\rdt} \,\frac{\delta_{k}[(\bar{e})^{t+\rdt}]} {{e_3w}^{t+\rdt}}   \right]   \\ 
     502    % 
     503    - &c_\epsilon \; \left( \frac{\sqrt{\bar {e}}}{l_\epsilon}\right)^{t-\rdt}\,(\bar {e})^{t+\rdt} 
     504  \end{split} 
    486505\end{equation} 
    487506where the last two terms in \autoref{eq:zdftke_ene} (vertical diffusion and Kolmogorov dissipation) 
     
    511530$k$-$\omega$ \citep{Wilcox_1988} among others \citep{Umlauf_Burchard_JMS03,Kantha_Carniel_CSR05}).  
    512531The GLS scheme is given by the following set of equations: 
    513 \begin{equation} \label{eq:zdfgls_e} 
    514 \frac{\partial \bar{e}}{\partial t} =  
    515 \frac{K_m}{\sigma_e e_3 }\;\left[ {\left( \frac{\partial u}{\partial k} \right)^2 
    516                                                    +\left( \frac{\partial v}{\partial k} \right)^2} \right] 
    517 -K_\rho \,N^2 
    518 +\frac{1}{e_3}\,\frac{\partial}{\partial k} \left[ \frac{K_m}{e_3}\,\frac{\partial \bar{e}}{\partial k} \right] 
    519 - \epsilon 
     532\begin{equation} 
     533  \label{eq:zdfgls_e} 
     534  \frac{\partial \bar{e}}{\partial t} = 
     535  \frac{K_m}{\sigma_e e_3 }\;\left[ {\left( \frac{\partial u}{\partial k} \right)^2 
     536      +\left( \frac{\partial v}{\partial k} \right)^2} \right] 
     537  -K_\rho \,N^2 
     538  +\frac{1}{e_3}\,\frac{\partial}{\partial k} \left[ \frac{K_m}{e_3}\,\frac{\partial \bar{e}}{\partial k} \right] 
     539  - \epsilon 
    520540\end{equation} 
    521541 
    522 \begin{equation} \label{eq:zdfgls_psi} 
    523    \begin{split} 
    524 \frac{\partial \psi}{\partial t} =& \frac{\psi}{\bar{e}} \left\{ 
    525 \frac{C_1\,K_m}{\sigma_{\psi} {e_3}}\;\left[ {\left( \frac{\partial u}{\partial k} \right)^2 
    526                                                                    +\left( \frac{\partial v}{\partial k} \right)^2} \right] 
    527 - C_3 \,K_\rho\,N^2   - C_2 \,\epsilon \,Fw   \right\}             \\ 
    528 &+\frac{1}{e_3}  \;\frac{\partial }{\partial k}\left[ {\frac{K_m}{e_3 } 
    529                                   \;\frac{\partial \psi}{\partial k}} \right]\; 
    530    \end{split} 
    531 \end{equation} 
    532  
    533 \begin{equation} \label{eq:zdfgls_kz} 
    534    \begin{split} 
    535          K_m    &= C_{\mu} \ \sqrt {\bar{e}} \ l         \\ 
    536          K_\rho &= C_{\mu'}\ \sqrt {\bar{e}} \ l 
    537    \end{split} 
    538 \end{equation} 
    539  
    540 \begin{equation} \label{eq:zdfgls_eps} 
    541 {\epsilon} = C_{0\mu} \,\frac{\bar {e}^{3/2}}{l} \; 
    542 \end{equation} 
     542\[ 
     543  % \label{eq:zdfgls_psi} 
     544  \begin{split} 
     545    \frac{\partial \psi}{\partial t} =& \frac{\psi}{\bar{e}} \left\{ 
     546      \frac{C_1\,K_m}{\sigma_{\psi} {e_3}}\;\left[ {\left( \frac{\partial u}{\partial k} \right)^2 
     547          +\left( \frac{\partial v}{\partial k} \right)^2} \right] 
     548      - C_3 \,K_\rho\,N^2   - C_2 \,\epsilon \,Fw   \right\}             \\ 
     549    &+\frac{1}{e_3}  \;\frac{\partial }{\partial k}\left[ {\frac{K_m}{e_3 } 
     550        \;\frac{\partial \psi}{\partial k}} \right]\; 
     551  \end{split} 
     552\] 
     553 
     554\[ 
     555  % \label{eq:zdfgls_kz} 
     556  \begin{split} 
     557    K_m    &= C_{\mu} \ \sqrt {\bar{e}} \ l         \\ 
     558    K_\rho &= C_{\mu'}\ \sqrt {\bar{e}} \ l 
     559  \end{split} 
     560\] 
     561 
     562\[ 
     563  % \label{eq:zdfgls_eps} 
     564  {\epsilon} = C_{0\mu} \,\frac{\bar {e}^{3/2}}{l} \; 
     565\] 
    543566where $N$ is the local Brunt-Vais\"{a}l\"{a} frequency (see \autoref{subsec:TRA_bn2}) and 
    544567$\epsilon$ the dissipation rate.  
     
    549572 
    550573%--------------------------------------------------TABLE-------------------------------------------------- 
    551 \begin{table}[htbp]  \begin{center} 
    552 %\begin{tabular}{cp{70pt}cp{70pt}cp{70pt}cp{70pt}cp{70pt}cp{70pt}c} 
    553 \begin{tabular}{ccccc} 
    554                          &   $k-kl$   & $k-\epsilon$ & $k-\omega$ &   generic   \\   
    555 %                        & \citep{Mellor_Yamada_1982} &  \citep{Rodi_1987}       & \citep{Wilcox_1988} &                 \\   
    556 \hline  \hline  
    557 \np{nn\_clo}     & \textbf{0} &   \textbf{1}  &   \textbf{2}   &    \textbf{3}   \\   
    558 \hline  
    559 $( p , n , m )$          &   ( 0 , 1 , 1 )   & ( 3 , 1.5 , -1 )   & ( -1 , 0.5 , -1 )    &  ( 2 , 1 , -0.67 )  \\ 
    560 $\sigma_k$      &    2.44         &     1.              &      2.                &      0.8          \\ 
    561 $\sigma_\psi$  &    2.44         &     1.3            &      2.                 &       1.07       \\ 
    562 $C_1$              &      0.9         &     1.44          &      0.555          &       1.           \\ 
    563 $C_2$              &      0.5         &     1.92          &      0.833          &       1.22       \\ 
    564 $C_3$              &      1.           &     1.              &      1.                &       1.           \\ 
    565 $F_{wall}$        &      Yes        &       --             &     --                  &      --          \\ 
    566 \hline 
    567 \hline 
    568 \end{tabular} 
    569 \caption{   \protect\label{tab:GLS}  
    570   Set of predefined GLS parameters, or equivalently predefined turbulence models available with 
    571   \protect\key{zdfgls} and controlled by the \protect\np{nn\_clos} namelist variable in \protect\ngn{namzdf\_gls}.} 
    572 \end{center}   \end{table} 
     574\begin{table}[htbp] 
     575  \begin{center} 
     576    % \begin{tabular}{cp{70pt}cp{70pt}cp{70pt}cp{70pt}cp{70pt}cp{70pt}c} 
     577    \begin{tabular}{ccccc} 
     578      &   $k-kl$   & $k-\epsilon$ & $k-\omega$ &   generic   \\ 
     579      % & \citep{Mellor_Yamada_1982} &  \citep{Rodi_1987}       & \citep{Wilcox_1988} &                 \\ 
     580      \hline 
     581      \hline 
     582      \np{nn\_clo}     & \textbf{0} &   \textbf{1}  &   \textbf{2}   &    \textbf{3}   \\ 
     583      \hline 
     584      $( p , n , m )$          &   ( 0 , 1 , 1 )   & ( 3 , 1.5 , -1 )   & ( -1 , 0.5 , -1 )    &  ( 2 , 1 , -0.67 )  \\ 
     585      $\sigma_k$      &    2.44         &     1.              &      2.                &      0.8          \\ 
     586      $\sigma_\psi$  &    2.44         &     1.3            &      2.                 &       1.07       \\ 
     587      $C_1$              &      0.9         &     1.44          &      0.555          &       1.           \\ 
     588      $C_2$              &      0.5         &     1.92          &      0.833          &       1.22       \\ 
     589      $C_3$              &      1.           &     1.              &      1.                &       1.           \\ 
     590      $F_{wall}$        &      Yes        &       --             &     --                  &      --          \\ 
     591      \hline 
     592      \hline 
     593    \end{tabular} 
     594    \caption{ 
     595      \protect\label{tab:GLS} 
     596      Set of predefined GLS parameters, or equivalently predefined turbulence models available with 
     597      \protect\key{zdfgls} and controlled by the \protect\np{nn\_clos} namelist variable in \protect\ngn{namzdf\_gls}. 
     598    } 
     599  \end{center} 
     600\end{table} 
    573601%-------------------------------------------------------------------------------------------------------------- 
    574602 
     
    646674 
    647675%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    648 \begin{figure}[!htb]    \begin{center} 
    649 \includegraphics[width=0.90\textwidth]{Fig_npc} 
    650 \caption{  \protect\label{fig:npc}  
    651   Example of an unstable density profile treated by the non penetrative convective adjustment algorithm. 
    652   $1^{st}$ step: the initial profile is checked from the surface to the bottom. 
    653   It is found to be unstable between levels 3 and 4. 
    654   They are mixed. 
    655   The resulting $\rho$ is still larger than $\rho$(5): levels 3 to 5 are mixed. 
    656   The resulting $\rho$ is still larger than $\rho$(6): levels 3 to 6 are mixed. 
    657   The $1^{st}$ step ends since the density profile is then stable below the level 3. 
    658   $2^{nd}$ step: the new $\rho$ profile is checked following the same procedure as in $1^{st}$ step: 
    659   levels 2 to 5 are mixed. 
    660   The new density profile is checked. 
    661   It is found stable: end of algorithm.} 
    662 \end{center}   \end{figure} 
     676\begin{figure}[!htb] 
     677  \begin{center} 
     678    \includegraphics[width=0.90\textwidth]{Fig_npc} 
     679    \caption{ 
     680      \protect\label{fig:npc} 
     681      Example of an unstable density profile treated by the non penetrative convective adjustment algorithm. 
     682      $1^{st}$ step: the initial profile is checked from the surface to the bottom. 
     683      It is found to be unstable between levels 3 and 4. 
     684      They are mixed. 
     685      The resulting $\rho$ is still larger than $\rho$(5): levels 3 to 5 are mixed. 
     686      The resulting $\rho$ is still larger than $\rho$(6): levels 3 to 6 are mixed. 
     687      The $1^{st}$ step ends since the density profile is then stable below the level 3. 
     688      $2^{nd}$ step: the new $\rho$ profile is checked following the same procedure as in $1^{st}$ step: 
     689      levels 2 to 5 are mixed. 
     690      The new density profile is checked. 
     691      It is found stable: end of algorithm. 
     692    } 
     693  \end{center} 
     694\end{figure} 
    663695%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    664696 
     
    781813 
    782814Diapycnal mixing of S and T are described by diapycnal diffusion coefficients  
    783 \begin{align*} % \label{eq:zdfddm_Kz} 
    784     &A^{vT} = A_o^{vT}+A_f^{vT}+A_d^{vT}  \\ 
    785     &A^{vS} = A_o^{vS}+A_f^{vS}+A_d^{vS} 
     815\begin{align*} 
     816  % \label{eq:zdfddm_Kz} 
     817  &A^{vT} = A_o^{vT}+A_f^{vT}+A_d^{vT} \\ 
     818  &A^{vS} = A_o^{vS}+A_f^{vS}+A_d^{vS} 
    786819\end{align*} 
    787820where subscript $f$ represents mixing by salt fingering, $d$ by diffusive convection, 
     
    792825To represent mixing of $S$ and $T$ by salt fingering, we adopt the diapycnal diffusivities suggested by Schmitt 
    793826(1981): 
    794 \begin{align} \label{eq:zdfddm_f} 
    795 A_f^{vS} &=    \begin{cases} 
    796    \frac{A^{\ast v}}{1+(R_\rho / R_c)^n   } &\text{if  $R_\rho > 1$ and $N^2>0$ } \\ 
    797    0                              &\text{otherwise}  
    798             \end{cases}    
    799 \\           \label{eq:zdfddm_f_T} 
    800 A_f^{vT} &= 0.7 \ A_f^{vS} / R_\rho  
     827\begin{align} 
     828  \label{eq:zdfddm_f} 
     829  A_f^{vS} &= 
     830             \begin{cases} 
     831               \frac{A^{\ast v}}{1+(R_\rho / R_c)^n   } &\text{if  $R_\rho > 1$ and $N^2>0$ } \\ 
     832               0                              &\text{otherwise} 
     833             \end{cases} 
     834  \\         \label{eq:zdfddm_f_T} 
     835  A_f^{vT} &= 0.7 \ A_f^{vS} / R_\rho  
    801836\end{align} 
    802837 
    803838%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    804 \begin{figure}[!t]   \begin{center} 
    805 \includegraphics[width=0.99\textwidth]{Fig_zdfddm} 
    806 \caption{  \protect\label{fig:zdfddm} 
    807   From \citet{Merryfield1999} : 
    808   (a) Diapycnal diffusivities $A_f^{vT}$ and $A_f^{vS}$ for temperature and salt in regions of salt fingering. 
    809   Heavy curves denote $A^{\ast v} = 10^{-3}~m^2.s^{-1}$ and thin curves $A^{\ast v} = 10^{-4}~m^2.s^{-1}$; 
    810   (b) diapycnal diffusivities $A_d^{vT}$ and $A_d^{vS}$ for temperature and salt in regions of diffusive convection. 
    811   Heavy curves denote the Federov parameterisation and thin curves the Kelley parameterisation. 
    812   The latter is not implemented in \NEMO. } 
    813 \end{center}    \end{figure} 
     839\begin{figure}[!t] 
     840  \begin{center} 
     841    \includegraphics[width=0.99\textwidth]{Fig_zdfddm} 
     842    \caption{ 
     843      \protect\label{fig:zdfddm} 
     844      From \citet{Merryfield1999} : 
     845      (a) Diapycnal diffusivities $A_f^{vT}$ and $A_f^{vS}$ for temperature and salt in regions of salt fingering. 
     846      Heavy curves denote $A^{\ast v} = 10^{-3}~m^2.s^{-1}$ and thin curves $A^{\ast v} = 10^{-4}~m^2.s^{-1}$; 
     847      (b) diapycnal diffusivities $A_d^{vT}$ and $A_d^{vS}$ for temperature and salt in regions of 
     848      diffusive convection. 
     849      Heavy curves denote the Federov parameterisation and thin curves the Kelley parameterisation. 
     850      The latter is not implemented in \NEMO. 
     851    } 
     852  \end{center} 
     853\end{figure} 
    814854%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    815855 
     
    820860To represent mixing of S and T by diffusive layering,  the diapycnal diffusivities suggested by 
    821861Federov (1988) is used:  
    822 \begin{align}  \label{eq:zdfddm_d} 
    823 A_d^{vT} &=    \begin{cases} 
    824    1.3635 \, \exp{\left( 4.6\, \exp{ \left[  -0.54\,( R_{\rho}^{-1} - 1 )  \right] }    \right)} 
    825                            &\text{if  $0<R_\rho < 1$ and $N^2>0$ } \\ 
    826    0                       &\text{otherwise}  
    827             \end{cases}    
    828 \\          \label{eq:zdfddm_d_S} 
    829 A_d^{vS} &=    \begin{cases} 
    830    A_d^{vT}\ \left( 1.85\,R_{\rho} - 0.85 \right) 
    831                            &\text{if  $0.5 \leq R_\rho<1$ and $N^2>0$ } \\ 
    832    A_d^{vT} \ 0.15 \ R_\rho 
    833                            &\text{if  $\ \ 0 < R_\rho<0.5$ and $N^2>0$ } \\ 
    834    0                       &\text{otherwise}  
    835             \end{cases}    
     862\begin{align} 
     863  % \label{eq:zdfddm_d} 
     864  A_d^{vT} &= 
     865             \begin{cases} 
     866               1.3635 \, \exp{\left( 4.6\, \exp{ \left[  -0.54\,( R_{\rho}^{-1} - 1 )  \right] }    \right)} 
     867               &\text{if  $0<R_\rho < 1$ and $N^2>0$ } \\ 
     868               0                       &\text{otherwise} 
     869             \end{cases} 
     870                                       \nonumber \\ 
     871  \label{eq:zdfddm_d_S} 
     872  A_d^{vS} &= 
     873             \begin{cases} 
     874               A_d^{vT}\ \left( 1.85\,R_{\rho} - 0.85 \right) &\text{if  $0.5 \leq R_\rho<1$ and $N^2>0$ } \\ 
     875               A_d^{vT} \ 0.15 \ R_\rho               &\text{if  $\ \ 0 < R_\rho<0.5$ and $N^2>0$ } \\ 
     876               0                       &\text{otherwise} 
     877             \end{cases} 
    836878\end{align} 
    837879 
     
    863905a condition on the vertical diffusive flux. 
    864906For the bottom boundary layer, one has: 
    865 \begin{equation} \label{eq:zdfbfr_flux} 
    866 A^{vm} \left( \partial {\textbf U}_h / \partial z \right) = {{\cal F}}_h^{\textbf U} 
    867 \end{equation} 
     907\[ 
     908  % \label{eq:zdfbfr_flux} 
     909  A^{vm} \left( \partial {\textbf U}_h / \partial z \right) = {{\cal F}}_h^{\textbf U} 
     910\] 
    868911where ${\cal F}_h^{\textbf U}$ is represents the downward flux of horizontal momentum outside 
    869912the logarithmic turbulent boundary layer (thickness of the order of 1~m in the ocean). 
     
    878921bottom model layer. 
    879922To illustrate this, consider the equation for $u$ at $k$, the last ocean level: 
    880 \begin{equation} \label{eq:zdfbfr_flux2} 
    881 \frac{\partial u_k}{\partial t} = \frac{1}{e_{3u}} \left[ \frac{A_{uw}^{vm}}{e_{3uw}} \delta_{k+1/2}\;[u] - {\cal F}^u_h \right] \approx - \frac{{\cal F}^u_{h}}{e_{3u}} 
     923\begin{equation} 
     924  \label{eq:zdfbfr_flux2} 
     925  \frac{\partial u_k}{\partial t} = \frac{1}{e_{3u}} \left[ \frac{A_{uw}^{vm}}{e_{3uw}} \delta_{k+1/2}\;[u] - {\cal F}^u_h \right] \approx - \frac{{\cal F}^u_{h}}{e_{3u}} 
    882926\end{equation} 
    883927If the bottom layer thickness is 200~m, the Ekman transport will be distributed over that depth. 
     
    897941bottom velocities and geometric values to provide the momentum trend due to bottom friction. 
    898942These coefficients are computed in \mdl{zdfbfr} and generally take the form $c_b^{\textbf U}$ where: 
    899 \begin{equation} \label{eq:zdfbfr_bdef} 
    900 \frac{\partial {\textbf U_h}}{\partial t} =  
     943\begin{equation} 
     944  \label{eq:zdfbfr_bdef} 
     945  \frac{\partial {\textbf U_h}}{\partial t} = 
    901946  - \frac{{\cal F}^{\textbf U}_{h}}{e_{3u}} = \frac{c_b^{\textbf U}}{e_{3u}} \;{\textbf U}_h^b 
    902947\end{equation} 
     
    911956The linear bottom friction parameterisation (including the special case of a free-slip condition) assumes that 
    912957the bottom friction is proportional to the interior velocity (i.e. the velocity of the last model level): 
    913 \begin{equation} \label{eq:zdfbfr_linear} 
    914 {\cal F}_h^\textbf{U} = \frac{A^{vm}}{e_3} \; \frac{\partial \textbf{U}_h}{\partial k} = r \; \textbf{U}_h^b 
    915 \end{equation} 
     958\[ 
     959  % \label{eq:zdfbfr_linear} 
     960  {\cal F}_h^\textbf{U} = \frac{A^{vm}}{e_3} \; \frac{\partial \textbf{U}_h}{\partial k} = r \; \textbf{U}_h^b 
     961\] 
    916962where $r$ is a friction coefficient expressed in ms$^{-1}$. 
    917963This coefficient is generally estimated by setting a typical decay time $\tau$ in the deep ocean,  
     
    927973 
    928974For the linear friction case the coefficients defined in the general expression \autoref{eq:zdfbfr_bdef} are:  
    929 \begin{equation} \label{eq:zdfbfr_linbfr_b} 
    930 \begin{split} 
    931  c_b^u &= - r\\ 
    932  c_b^v &= - r\\ 
    933 \end{split} 
    934 \end{equation} 
     975\[ 
     976  % \label{eq:zdfbfr_linbfr_b} 
     977  \begin{split} 
     978    c_b^u &= - r\\ 
     979    c_b^v &= - r\\ 
     980  \end{split} 
     981\] 
    935982When \np{nn\_botfr}\forcode{ = 1}, the value of $r$ used is \np{rn\_bfri1}. 
    936983Setting \np{nn\_botfr}\forcode{ = 0} is equivalent to setting $r=0$ and 
     
    950997 
    951998The non-linear bottom friction parameterisation assumes that the bottom friction is quadratic:  
    952 \begin{equation} \label{eq:zdfbfr_nonlinear} 
    953 {\cal F}_h^\textbf{U} = \frac{A^{vm}}{e_3 }\frac{\partial \textbf {U}_h  
    954 }{\partial k}=C_D \;\sqrt {u_b ^2+v_b ^2+e_b } \;\; \textbf {U}_h^b  
    955 \end{equation} 
     999\[ 
     1000  % \label{eq:zdfbfr_nonlinear} 
     1001  {\cal F}_h^\textbf{U} = \frac{A^{vm}}{e_3 }\frac{\partial \textbf {U}_h 
     1002  }{\partial k}=C_D \;\sqrt {u_b ^2+v_b ^2+e_b } \;\; \textbf {U}_h^b 
     1003\] 
    9561004where $C_D$ is a drag coefficient, and $e_b $ a bottom turbulent kinetic energy due to tides, 
    9571005internal waves breaking and other short time scale currents. 
     
    9651013the bottom friction to the general momentum trend in \mdl{dynbfr}. 
    9661014For the non-linear friction case the terms computed in \mdl{zdfbfr} are: 
    967 \begin{equation} \label{eq:zdfbfr_nonlinbfr} 
    968 \begin{split} 
    969  c_b^u &= - \; C_D\;\left[ u^2 + \left(\bar{\bar{v}}^{i+1,j}\right)^2 + e_b \right]^{1/2}\\ 
    970  c_b^v &= - \; C_D\;\left[  \left(\bar{\bar{u}}^{i,j+1}\right)^2 + v^2 + e_b \right]^{1/2}\\ 
    971 \end{split} 
    972 \end{equation} 
     1015\[ 
     1016  % \label{eq:zdfbfr_nonlinbfr} 
     1017  \begin{split} 
     1018    c_b^u &= - \; C_D\;\left[ u^2 + \left(\bar{\bar{v}}^{i+1,j}\right)^2 + e_b \right]^{1/2}\\ 
     1019    c_b^v &= - \; C_D\;\left[  \left(\bar{\bar{u}}^{i,j+1}\right)^2 + v^2 + e_b \right]^{1/2}\\ 
     1020  \end{split} 
     1021\] 
    9731022 
    9741023The coefficients that control the strength of the non-linear bottom friction are initialised as namelist parameters: 
     
    9911040If  \np{ln\_loglayer} = .true., $C_D$ is no longer constant but is related to the thickness of 
    9921041the last wet layer in each column by: 
    993 \begin{equation} 
    994 C_D = \left ( {\kappa \over {\rm log}\left ( 0.5e_{3t}/rn\_bfrz0 \right ) } \right )^2 
    995 \end{equation} 
     1042\[ 
     1043  C_D = \left ( {\kappa \over {\rm log}\left ( 0.5e_{3t}/rn\_bfrz0 \right ) } \right )^2 
     1044\] 
    9961045 
    9971046\noindent where $\kappa$ is the von-Karman constant and \np{rn\_bfrz0} is a roughness length provided via 
     
    10011050the base \np{rn\_bfri2} value and it is not allowed to exceed the value of an additional namelist parameter: 
    10021051\np{rn\_bfri2\_max}, i.e.: 
    1003 \begin{equation} 
    1004 rn\_bfri2 \leq C_D \leq rn\_bfri2\_max 
    1005 \end{equation} 
     1052\[ 
     1053  rn\_bfri2 \leq C_D \leq rn\_bfri2\_max 
     1054\] 
    10061055 
    10071056\noindent Note also that a log-layer enhancement can also be applied to the top boundary friction if 
     
    10181067bottom friction does not induce numerical instability. 
    10191068For the purposes of stability analysis, an approximation to \autoref{eq:zdfbfr_flux2} is: 
    1020 \begin{equation} \label{eq:Eqn_bfrstab} 
    1021 \begin{split} 
    1022  \Delta u &= -\frac{{{\cal F}_h}^u}{e_{3u}}\;2 \rdt    \\ 
    1023                &= -\frac{ru}{e_{3u}}\;2\rdt\\ 
    1024 \end{split} 
     1069\begin{equation} 
     1070  \label{eq:Eqn_bfrstab} 
     1071  \begin{split} 
     1072    \Delta u &= -\frac{{{\cal F}_h}^u}{e_{3u}}\;2 \rdt    \\ 
     1073    &= -\frac{ru}{e_{3u}}\;2\rdt\\ 
     1074  \end{split} 
    10251075\end{equation} 
    10261076\noindent where linear bottom friction and a leapfrog timestep have been assumed. 
    10271077To ensure that the bottom friction cannot reverse the direction of flow it is necessary to have: 
    1028 \begin{equation} 
    1029  |\Delta u| < \;|u|  
    1030 \end{equation} 
     1078\[ 
     1079  |\Delta u| < \;|u|  
     1080\] 
    10311081\noindent which, using \autoref{eq:Eqn_bfrstab}, gives: 
    1032 \begin{equation} 
    1033 r\frac{2\rdt}{e_{3u}} < 1 \qquad  \Rightarrow \qquad r < \frac{e_{3u}}{2\rdt}\\ 
    1034 \end{equation} 
     1082\[ 
     1083  r\frac{2\rdt}{e_{3u}} < 1 \qquad  \Rightarrow \qquad r < \frac{e_{3u}}{2\rdt}\\ 
     1084\] 
    10351085This same inequality can also be derived in the non-linear bottom friction case if 
    10361086a velocity of 1 m.s$^{-1}$ is assumed. 
    10371087Alternatively, this criterion can be rearranged to suggest a minimum bottom box thickness to ensure stability: 
    1038 \begin{equation} 
    1039 e_{3u} > 2\;r\;\rdt 
    1040 \end{equation} 
     1088\[ 
     1089  e_{3u} > 2\;r\;\rdt 
     1090\] 
    10411091\noindent which it may be necessary to impose if partial steps are being used. 
    10421092For example, if $|u| = 1$ m.s$^{-1}$, $rdt = 1800$ s, $r = 10^{-3}$ then $e_{3u}$ should be greater than 3.6 m. 
     
    10701120the bottom boundary condition is implemented implicitly. 
    10711121 
    1072 \begin{equation} \label{eq:dynzdf_bfr} 
    1073 \left.{\left( {\frac{A^{vm} }{e_3 }\ \frac{\partial \textbf{U}_h}{\partial k}} \right)} \right|_{mbk} 
    1074     = \binom{c_{b}^{u}u^{n+1}_{mbk}}{c_{b}^{v}v^{n+1}_{mbk}} 
    1075 \end{equation} 
     1122\[ 
     1123  % \label{eq:dynzdf_bfr} 
     1124  \left.{\left( {\frac{A^{vm} }{e_3 }\ \frac{\partial \textbf{U}_h}{\partial k}} \right)} \right|_{mbk} 
     1125  = \binom{c_{b}^{u}u^{n+1}_{mbk}}{c_{b}^{v}v^{n+1}_{mbk}} 
     1126\] 
    10761127 
    10771128where $mbk$ is the layer number of the bottom wet layer. 
     
    10891140The implementation of the implicit bottom friction in \mdl{dynspg\_ts} is done in two steps as the following: 
    10901141 
    1091 \begin{equation} \label{eq:dynspg_ts_bfr1} 
    1092 \frac{\textbf{U}_{med}-\textbf{U}^{m-1}}{2\Delta t}=-g\nabla\eta-f\textbf{k}\times\textbf{U}^{m}+c_{b} 
    1093 \left(\textbf{U}_{med}-\textbf{U}^{m-1}\right) 
    1094 \end{equation} 
    1095 \begin{equation} \label{eq:dynspg_ts_bfr2} 
    1096 \frac{\textbf{U}^{m+1}-\textbf{U}_{med}}{2\Delta t}=\textbf{T}+ 
    1097 \left(g\nabla\eta^{'}+f\textbf{k}\times\textbf{U}^{'}\right)- 
    1098 2\Delta t_{bc}c_{b}\left(g\nabla\eta^{'}+f\textbf{k}\times\textbf{u}_{b}\right) 
    1099 \end{equation} 
     1142\[ 
     1143  % \label{eq:dynspg_ts_bfr1} 
     1144  \frac{\textbf{U}_{med}-\textbf{U}^{m-1}}{2\Delta t}=-g\nabla\eta-f\textbf{k}\times\textbf{U}^{m}+c_{b} 
     1145  \left(\textbf{U}_{med}-\textbf{U}^{m-1}\right) 
     1146\] 
     1147\[ 
     1148  \frac{\textbf{U}^{m+1}-\textbf{U}_{med}}{2\Delta t}=\textbf{T}+ 
     1149  \left(g\nabla\eta^{'}+f\textbf{k}\times\textbf{U}^{'}\right)- 
     1150  2\Delta t_{bc}c_{b}\left(g\nabla\eta^{'}+f\textbf{k}\times\textbf{u}_{b}\right) 
     1151\] 
    11001152 
    11011153where $\textbf{T}$ is the vertical integrated 3-D momentum trend. 
     
    11061158the 3-D baroclinic mode. 
    11071159$\textbf{u}_{b}$ is the bottom layer horizontal velocity. 
    1108  
    1109  
    1110  
    11111160 
    11121161% ------------------------------------------------------------------------------------------------------------- 
     
    11571206 
    11581207Otherwise, the implicit formulation takes the form: 
    1159 \begin{equation} \label{eq:zdfbfr_implicitts} 
    1160  \bar{U}^{t+ \rdt} = \; \left [ \bar{U}^{t-\rdt}\; + 2 \rdt\;RHS \right ] / \left [ 1 - 2 \rdt \;c_b^{u} / H_e \right ]   
    1161 \end{equation} 
     1208\[ 
     1209  % \label{eq:zdfbfr_implicitts} 
     1210  \bar{U}^{t+ \rdt} = \; \left [ \bar{U}^{t-\rdt}\; + 2 \rdt\;RHS \right ] / \left [ 1 - 2 \rdt \;c_b^{u} / H_e \right ] 
     1211\] 
    11621212where $\bar U$ is the barotropic velocity, $H_e$ is the full depth (including sea surface height),  
    11631213$c_b^u$ is the bottom friction coefficient as calculated in \rou{zdf\_bfr} and 
    11641214$RHS$ represents all the components to the vertically integrated momentum trend except for 
    11651215that due to bottom friction. 
    1166  
    1167  
    1168  
    11691216 
    11701217% ================================================================ 
     
    11921239$A^{vT}_{tides}$ is expressed as a function of $E(x,y)$, 
    11931240the energy transfer from barotropic tides to baroclinic tides: 
    1194 \begin{equation} \label{eq:Ktides} 
    1195 A^{vT}_{tides} =  q \,\Gamma \,\frac{ E(x,y) \, F(z) }{ \rho \, N^2 } 
     1241\begin{equation} 
     1242  \label{eq:Ktides} 
     1243  A^{vT}_{tides} =  q \,\Gamma \,\frac{ E(x,y) \, F(z) }{ \rho \, N^2 } 
    11961244\end{equation} 
    11971245where $\Gamma$ is the mixing efficiency, $N$ the Brunt-Vais\"{a}l\"{a} frequency (see \autoref{subsec:TRA_bn2}), 
     
    12091257with a vertical scale of $h_o$ (\np{rn\_htmx} namelist parameter, 
    12101258with a typical value of $500\,m$) \citep{St_Laurent_Nash_DSR04},  
    1211 \begin{equation} \label{eq:Fz} 
    1212 F(i,j,k) = \frac{ e^{ -\frac{H+z}{h_o} } }{ h_o \left( 1- e^{ -\frac{H}{h_o} } \right) } 
    1213 \end{equation} 
     1259\[ 
     1260  % \label{eq:Fz} 
     1261  F(i,j,k) = \frac{ e^{ -\frac{H+z}{h_o} } }{ h_o \left( 1- e^{ -\frac{H}{h_o} } \right) } 
     1262\] 
    12141263and is normalized so that vertical integral over the water column is unity.  
    12151264 
     
    12341283 
    12351284%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    1236 \begin{figure}[!t]   \begin{center} 
    1237 \includegraphics[width=0.90\textwidth]{Fig_ZDF_M2_K1_tmx} 
    1238 \caption{  \protect\label{fig:ZDF_M2_K1_tmx}  
    1239 (a) M2 and (b) K1 internal wave drag energy from \citet{Carrere_Lyard_GRL03} ($W/m^2$). } 
    1240 \end{center}   \end{figure} 
     1285\begin{figure}[!t] 
     1286  \begin{center} 
     1287    \includegraphics[width=0.90\textwidth]{Fig_ZDF_M2_K1_tmx} 
     1288    \caption{ 
     1289      \protect\label{fig:ZDF_M2_K1_tmx} 
     1290      (a) M2 and (b) K1 internal wave drag energy from \citet{Carrere_Lyard_GRL03} ($W/m^2$). 
     1291    } 
     1292  \end{center} 
     1293\end{figure} 
    12411294%>>>>>>>>>>>>>>>>>>>>>>>>>>>>  
    12421295  
     
    12681321the energy dissipation proportional to $N^2$ below the core of the thermocline and to $N$ above.  
    12691322The resulting $F(z)$ is: 
    1270 \begin{equation} \label{eq:Fz_itf} 
    1271 F(i,j,k) \sim     \left\{ \begin{aligned} 
    1272 \frac{q\,\Gamma E(i,j) } {\rho N \, \int N     dz}    \qquad \text{when $\partial_z N < 0$} \\ 
    1273 \frac{q\,\Gamma E(i,j) } {\rho     \, \int N^2 dz}    \qquad \text{when $\partial_z N > 0$} 
    1274                       \end{aligned} \right. 
    1275 \end{equation} 
     1323\[ 
     1324  % \label{eq:Fz_itf} 
     1325  F(i,j,k) \sim     \left\{ 
     1326    \begin{aligned} 
     1327      \frac{q\,\Gamma E(i,j) } {\rho N \, \int N     dz}    \qquad \text{when $\partial_z N < 0$} \\ 
     1328      \frac{q\,\Gamma E(i,j) } {\rho     \, \int N^2 dz}    \qquad \text{when $\partial_z N > 0$} 
     1329    \end{aligned} 
     1330  \right. 
     1331\] 
    12761332 
    12771333Averaged over the ITF area, the resulting tidal mixing coefficient is $1.5\,cm^2/s$,  
     
    12831339global coupled GCMs \citep{Koch-Larrouy_al_CD10}. 
    12841340 
    1285  
    12861341% ================================================================ 
    12871342% Internal wave-driven mixing 
     
    12991354A three-dimensional field of internal wave energy dissipation $\epsilon(x,y,z)$ is first constructed, 
    13001355and the resulting diffusivity is obtained as  
    1301 \begin{equation} \label{eq:Kwave} 
    1302 A^{vT}_{wave} =  R_f \,\frac{ \epsilon }{ \rho \, N^2 } 
    1303 \end{equation} 
     1356\[ 
     1357  % \label{eq:Kwave} 
     1358  A^{vT}_{wave} =  R_f \,\frac{ \epsilon }{ \rho \, N^2 } 
     1359\] 
    13041360where $R_f$ is the mixing efficiency and $\epsilon$ is a specified three dimensional distribution of 
    13051361the energy available for mixing. 
     
    13231379(de Lavergne et al., in prep): 
    13241380\begin{align*} 
    1325 F_{cri}(i,j,k) &\propto e^{-h_{ab} / h_{cri} }\\ 
    1326 F_{pyc}(i,j,k) &\propto N^{n\_p}\\ 
    1327 F_{bot}(i,j,k) &\propto N^2 \, e^{- h_{wkb} / h_{bot} } 
     1381  F_{cri}(i,j,k) &\propto e^{-h_{ab} / h_{cri} }\\ 
     1382  F_{pyc}(i,j,k) &\propto N^{n\_p}\\ 
     1383  F_{bot}(i,j,k) &\propto N^2 \, e^{- h_{wkb} / h_{bot} } 
    13281384\end{align*}  
    13291385In the above formula, $h_{ab}$ denotes the height above bottom, 
    13301386$h_{wkb}$ denotes the WKB-stretched height above bottom, defined by 
    1331 \begin{equation*} 
    1332 h_{wkb} = H \, \frac{ \int_{-H}^{z} N \, dz' } { \int_{-H}^{\eta} N \, dz'  } \; , 
    1333 \end{equation*} 
     1387\[ 
     1388  h_{wkb} = H \, \frac{ \int_{-H}^{z} N \, dz' } { \int_{-H}^{\eta} N \, dz'  } \; , 
     1389\] 
    13341390The $n_p$ parameter (given by \np{nn\_zpyc} in \ngn{namzdf\_tmx\_new} namelist) 
    13351391controls the stratification-dependence of the pycnocline-intensified dissipation. 
     
    13431399% ================================================================ 
    13441400 
    1345  
     1401\biblio 
    13461402 
    13471403\end{document} 
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