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Changeset 7351 for branches/2016/dev_INGV_UKMO_2016/DOC/TexFiles/Chapters/Chap_DOM.tex – NEMO

Ignore:
Timestamp:
2016-11-28T17:04:10+01:00 (7 years ago)
Author:
emanuelaclementi
Message:

ticket #1805 step 3: /2016/dev_INGV_UKMO_2016 aligned to the trunk at revision 7161

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1 edited

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  • branches/2016/dev_INGV_UKMO_2016/DOC/TexFiles/Chapters/Chap_DOM.tex

    r5120 r7351  
     1\documentclass[NEMO_book]{subfiles} 
     2\begin{document} 
    13% ================================================================ 
    2 % Chapter 2 Space and Time Domain (DOM) 
     4% Chapter 2 ——— Space and Time Domain (DOM) 
    35% ================================================================ 
    46\chapter{Space Domain (DOM) } 
     
    4042%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    4143\begin{figure}[!tb]    \begin{center} 
    42 \includegraphics[width=0.90\textwidth]{./TexFiles/Figures/Fig_cell.pdf} 
     44\includegraphics[width=0.90\textwidth]{Fig_cell} 
    4345\caption{ \label{Fig_cell}     
    4446Arrangement of variables. $t$ indicates scalar points where temperature,  
     
    138140and $f$-points, and its divergence defined at $t$-points: 
    139141\begin{eqnarray}  \label{Eq_DOM_curl} 
    140  \nabla \times {\rm {\bf A}}\equiv & 
     142 \nabla \times {\rm{\bf A}}\equiv & 
    141143      \frac{1}{e_{2v}\,e_{3vw} } \ \left( \delta_{j +1/2} \left[e_{3w}\,a_3 \right] -\delta_{k+1/2} \left[e_{2v} \,a_2 \right] \right)  &\ \mathbf{i} \\  
    142144 +& \frac{1}{e_{2u}\,e_{3uw}} \ \left( \delta_{k+1/2} \left[e_{1u}\,a_1  \right] -\delta_{i +1/2} \left[e_{3w}\,a_3 \right] \right)  &\ \mathbf{j} \\ 
    143145 +& \frac{1}{e_{1f} \,e_{2f}    } \ \left( \delta_{i +1/2} \left[e_{2v}\,a_2  \right] -\delta_{j +1/2} \left[e_{1u}\,a_1 \right] \right)  &\ \mathbf{k} 
    144146 \end{eqnarray} 
    145 \begin{equation} \label{Eq_DOM_div} 
    146 \nabla \cdot \rm{\bf A}=\frac{1}{e_{1t}\,e_{2t}\,e_{3t}}\left( \delta_i \left[e_{2u}\,e_{3u}\,a_1 \right] 
    147                                                                                          +\delta_j \left[e_{1v}\,e_{3v}\,a_2 \right] \right)+\frac{1}{e_{3t} }\delta_k \left[a_3 \right] 
    148 \end{equation} 
    149  
    150 In the special case of a pure $z$-coordinate system, \eqref{Eq_DOM_lap} and  
    151 \eqref{Eq_DOM_div} can be simplified. In this case, the vertical scale factor  
    152 becomes a function of the single variable $k$ and thus does not depend on the  
    153 horizontal location of a grid point. For example \eqref{Eq_DOM_div} reduces to:  
    154 \begin{equation*} 
    155 \nabla \cdot \rm{\bf A}=\frac{1}{e_{1t}\,e_{2t}} \left( \delta_i \left[e_{2u}\,a_1 \right]  
    156                                                                               +\delta_j \left[e_{1v}\, a_2 \right]  \right) 
    157                                                      +\frac{1}{e_{3t}} \delta_k \left[             a_3 \right] 
    158 \end{equation*} 
     147\begin{eqnarray} \label{Eq_DOM_div} 
     148\nabla \cdot \rm{\bf A} \equiv  
     149    \frac{1}{e_{1t}\,e_{2t}\,e_{3t}} \left( \delta_i \left[e_{2u}\,e_{3u}\,a_1 \right] 
     150                                           +\delta_j \left[e_{1v}\,e_{3v}\,a_2 \right] \right)+\frac{1}{e_{3t} }\delta_k \left[a_3 \right] 
     151\end{eqnarray} 
    159152 
    160153The vertical average over the whole water column denoted by an overbar becomes  
     
    183176Let $a$ and $b$ be two fields defined on the mesh, with value zero inside  
    184177continental area. Using integration by parts it can be shown that the differencing  
    185 operators ($\delta_i$, $\delta_j$ and $\delta_k$) are anti-symmetric linear  
    186 operators, and further that the averaging operators $\overline{\,\cdot\,}^{\,i}$,  
     178operators ($\delta_i$, $\delta_j$ and $\delta_k$) are skew-symmetric linear operators,  
     179and further that the averaging operators $\overline{\,\cdot\,}^{\,i}$,  
    187180$\overline{\,\cdot\,}^{\,k}$ and $\overline{\,\cdot\,}^{\,k}$) are symmetric linear  
    188181operators, $i.e.$ 
     
    210203%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    211204\begin{figure}[!tb]  \begin{center} 
    212 \includegraphics[width=0.90\textwidth]{./TexFiles/Figures/Fig_index_hor.pdf} 
     205\includegraphics[width=0.90\textwidth]{Fig_index_hor} 
    213206\caption{   \label{Fig_index_hor}     
    214207Horizontal integer indexing used in the \textsc{Fortran} code. The dashed area indicates  
     
    260253%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    261254\begin{figure}[!pt]    \begin{center} 
    262 \includegraphics[width=.90\textwidth]{./TexFiles/Figures/Fig_index_vert.pdf} 
     255\includegraphics[width=.90\textwidth]{Fig_index_vert} 
    263256\caption{ \label{Fig_index_vert}      
    264257Vertical integer indexing used in the \textsc{Fortran } code. Note that  
     
    358351%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    359352\begin{figure}[!t]     \begin{center} 
    360 \includegraphics[width=0.90\textwidth]{./TexFiles/Figures/Fig_zgr_e3.pdf} 
     353\includegraphics[width=0.90\textwidth]{Fig_zgr_e3} 
    361354\caption{ \label{Fig_zgr_e3}     
    362355Comparison of (a) traditional definitions of grid-point position and grid-size in the vertical,  
     
    364357For both grids here,  the same $w$-point depth has been chosen but in (a) the  
    365358$t$-points are set half way between $w$-points while in (b) they are defined from  
    366 an analytical function: $z(k)=5\,(i-1/2)^3 - 45\,(i-1/2)^2 + 140\,(i-1/2) - 150$.  
     359an analytical function: $z(k)=5\,(k-1/2)^3 - 45\,(k-1/2)^2 + 140\,(k-1/2) - 150$.  
    367360Note the resulting difference between the value of the grid-size $\Delta_k$ and  
    368361those of the scale factor $e_k$. } 
     
    425418 
    426419The choice of the grid must be consistent with the boundary conditions specified  
    427 by the parameter \np{jperio} (see {\S\ref{LBC}). 
     420by \np{jperio}, a parameter found in \ngn{namcfg} namelist (see {\S\ref{LBC}). 
    428421 
    429422% ------------------------------------------------------------------------------------------------------------- 
     
    467460%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    468461\begin{figure}[!tb]    \begin{center} 
    469 \includegraphics[width=1.0\textwidth]{./TexFiles/Figures/Fig_z_zps_s_sps.pdf} 
     462\includegraphics[width=1.0\textwidth]{Fig_z_zps_s_sps} 
    470463\caption{  \label{Fig_z_zps_s_sps}    
    471464The ocean bottom as seen by the model:  
     
    475468(d) hybrid $s-z$ coordinate,  
    476469(e) hybrid $s-z$ coordinate with partial step, and  
    477 (f) same as (e) but with variable volume associated with the non-linear free surface.  
    478 Note that the variable volume option (\key{vvl}) can be used with any of the  
     470(f) same as (e) but in the non-linear free surface (\np{ln\_linssh}=false).  
     471Note that the non-linear free surface can be used with any of the  
    4794725 coordinates (a) to (e).} 
    480473\end{center}   \end{figure} 
    481474%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    482475 
    483 The choice of a vertical coordinate, even if it is made through a namelist parameter,  
     476The choice of a vertical coordinate, even if it is made through \ngn{namzgr} namelist parameters,  
    484477must be done once of all at the beginning of an experiment. It is not intended as an  
    485478option which can be enabled or disabled in the middle of an experiment. Three main  
     
    488481(\np{ln\_zps}~=~true), or generalized, $s$-coordinate (\np{ln\_sco}~=~true).  
    489482Hybridation of the three main coordinates are available: $s-z$ or $s-zps$ coordinate  
    490 (Fig.~\ref{Fig_z_zps_s_sps}d and \ref{Fig_z_zps_s_sps}e). When using the variable  
    491 volume option \key{vvl} ($i.e.$ non-linear free surface), the coordinate follow the  
    492 time-variation of the free surface so that the transformation is time dependent:  
    493 $z(i,j,k,t)$ (Fig.~\ref{Fig_z_zps_s_sps}f). This option can be used with full step  
    494 bathymetry or $s$-coordinate (hybrid and partial step coordinates have not  
    495 yet been tested in NEMO v2.3). If using $z$-coordinate with partial step bathymetry 
    496 (\np{ln\_zps}~=~true), ocean cavity beneath ice shelves can be open (\np{ln\_isfcav}~=~true). 
     483(Fig.~\ref{Fig_z_zps_s_sps}d and \ref{Fig_z_zps_s_sps}e). By default a non-linear free surface is used: 
     484the coordinate follow the time-variation of the free surface so that the transformation is time dependent:  
     485$z(i,j,k,t)$ (Fig.~\ref{Fig_z_zps_s_sps}f). When a linear free surface is assumed (\np{ln\_linssh}=true),  
     486the vertical coordinate are fixed in time, but the seawater can move up and down across the z=0 surface  
     487(in other words, the top of the ocean in not a rigid-lid).  
     488The last choice in terms of vertical coordinate concerns the presence (or not) in the model domain  
     489of ocean cavities beneath ice shelves. Setting \np{ln\_isfcav} to true allows to manage ocean cavities,  
     490otherwise they are filled in. This option is currently only available in $z$- or $zps$-coordinate, 
     491and partial step are also applied at the ocean/ice shelf interface.  
    497492 
    498493Contrary to the horizontal grid, the vertical grid is computed in the code and no  
    499494provision is made for reading it from a file. The only input file is the bathymetry  
    500 (in meters) (\ifile{bathy\_meter})  
     495(in meters) (\ifile{bathy\_meter}).  
    501496\footnote{N.B. in full step $z$-coordinate, a \ifile{bathy\_level} file can replace the  
    502497\ifile{bathy\_meter} file, so that the computation of the number of wet ocean point  
    503498in each water column is by-passed}.  
     499If \np{ln\_isfcav}~=~true, an extra file input file describing the ice shelf draft  
     500(in meters) (\ifile{isf\_draft\_meter}) is needed. 
     501 
    504502After reading the bathymetry, the algorithm for vertical grid definition differs  
    505503between the different options: 
     
    519517%%% 
    520518 
    521 The arrays describing the grid point depths and vertical scale factors  
    522 are three dimensional arrays $(i,j,k)$ even in the case of $z$-coordinate with  
    523 full step bottom topography. In non-linear free surface (\key{vvl}), their knowledge 
    524 is required at \textit{before}, \textit{now} and \textit{after} time step, while they  
    525 do not vary in time in linear free surface case.  
    526 To improve the code readability while providing this flexibility, the vertical coordinate  
    527 and scale factors are defined as functions of  
    528 $(i,j,k)$ with "fs" as prefix (examples: \textit{fse3t\_b, fse3t\_n, fse3t\_a,}  
    529 for the  \textit{before}, \textit{now} and \textit{after} scale factors at $t$-point)  
    530 that can be either three different arrays when \key{vvl} is defined, or a single fixed arrays.  
    531 These functions are defined in the file \hf{domzgr\_substitute} of the DOM directory.  
    532 They are used throughout the code, and replaced by the corresponding arrays at  
    533 the time of pre-processing (CPP capability). 
     519Unless a linear free surface is used (\np{ln\_linssh}=false), the arrays describing  
     520the grid point depths and vertical scale factors are three set of three dimensional arrays $(i,j,k)$  
     521defined at \textit{before}, \textit{now} and \textit{after} time step. The time at which they are 
     522defined is indicated by a suffix:$\_b$, $\_n$, or $\_a$, respectively. They are updated at each model time step 
     523using a fixed reference coordinate system which computer names have a $\_0$ suffix.  
     524When the linear free surface option is used (\np{ln\_linssh}=true), \textit{before}, \textit{now}  
     525and \textit{after} arrays are simply set one for all to their reference counterpart.  
     526 
    534527 
    535528% ------------------------------------------------------------------------------------------------------------- 
     
    540533 
    541534Three options are possible for defining the bathymetry, according to the  
    542 namelist variable \np{nn\_bathy}:  
     535namelist variable \np{nn\_bathy} (found in \ngn{namdom} namelist):  
    543536\begin{description} 
    544537\item[\np{nn\_bathy} = 0] a flat-bottom domain is defined. The total depth $z_w (jpk)$  
     
    548541domain width at the central latitude. This is meant for the "EEL-R5" configuration,  
    549542a periodic or open boundary channel with a seamount.  
    550 \item[\np{nn\_bathy} = 1] read a bathymetry. The \ifile{bathy\_meter} file (Netcdf format)  
    551 provides the ocean depth (positive, in meters) at each grid point of the model grid.  
    552 The bathymetry is usually built by interpolating a standard bathymetry product  
     543\item[\np{nn\_bathy} = 1] read a bathymetry and ice shelf draft (if needed). 
     544 The \ifile{bathy\_meter} file (Netcdf format) provides the ocean depth (positive, in meters) 
     545 at each grid point of the model grid. The bathymetry is usually built by interpolating a standard bathymetry product  
    553546($e.g.$ ETOPO2) onto the horizontal ocean mesh. Defining the bathymetry also  
    554547defines the coastline: where the bathymetry is zero, no model levels are defined  
    555548(all levels are masked). 
     549 
     550The \ifile{isfdraft\_meter} file (Netcdf format) provides the ice shelf draft (positive, in meters) 
     551 at each grid point of the model grid. This file is only needed if \np{ln\_isfcav}~=~true.  
     552Defining the ice shelf draft will also define the ice shelf edge and the grounding line position. 
    556553\end{description} 
    557554 
     
    573570%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    574571\begin{figure}[!tb]    \begin{center} 
    575 \includegraphics[width=0.90\textwidth]{./TexFiles/Figures/Fig_zgr.pdf} 
     572\includegraphics[width=0.90\textwidth]{Fig_zgr} 
    576573\caption{ \label{Fig_zgr}     
    577574Default vertical mesh for ORCA2: 30 ocean levels (L30). Vertical level functions for  
     
    610607(Fig.~\ref{Fig_zgr}). 
    611608 
     609If the ice shelf cavities are opened (\np{ln\_isfcav}=~true~}), the definition of $z_0$ is the same.  
     610However, definition of $e_3^0$ at $t$- and $w$-points is respectively changed to: 
     611\begin{equation} \label{DOM_zgr_ana} 
     612\begin{split} 
     613 e_3^T(k) &= z_W (k+1) - z_W (k)   \\ 
     614 e_3^W(k) &= z_T (k)   - z_T (k-1) \\ 
     615\end{split} 
     616\end{equation} 
     617This formulation decrease the self-generated circulation into the ice shelf cavity  
     618(which can, in extreme case, leads to blow up).\\ 
     619 
     620  
    612621The most used vertical grid for ORCA2 has $10~m$ ($500~m)$ resolution in the  
    613622surface (bottom) layers and a depth which varies from 0 at the sea surface to a  
     
    721730usually 10\%, of the default thickness $e_{3t}(jk)$). 
    722731 
    723  \colorbox{yellow}{Add a figure here of pstep especially at last ocean level } 
     732\gmcomment{ \colorbox{yellow}{Add a figure here of pstep especially at last ocean level } } 
    724733 
    725734% ------------------------------------------------------------------------------------------------------------- 
     
    749758depth, since a mixed step-like and bottom-following representation of the  
    750759topography can be used (Fig.~\ref{Fig_z_zps_s_sps}d-e) or an envelop bathymetry can be defined (Fig.~\ref{Fig_z_zps_s_sps}f). 
    751 The namelist parameter \np{rn\_rmax} determines the slope at which the terrain-following coordinate intersects the sea bed and becomes a pseudo z-coordinate. The coordinate can also be hybridised by specifying \np{rn\_sbot\_min} and \np{rn\_sbot\_max} as the minimum and maximum depths at which the terrain-following vertical coordinate is calculated. 
    752  
    753 Options for stretching the coordinate are provided as examples, but care must be taken to ensure that the vertical stretch used is appropriate for the application. 
    754  
    755 The original default NEMO s-coordinate stretching is available if neither of the other options are specified as true (\np{ln\_sco\_SH94}~=~false and \np{ln\_sco\_SF12}~=~false.) This uses a depth independent $\tanh$ function for the stretching \citep{Madec_al_JPO96}: 
     760The namelist parameter \np{rn\_rmax} determines the slope at which the terrain-following coordinate intersects  
     761the sea bed and becomes a pseudo z-coordinate.  
     762The coordinate can also be hybridised by specifying \np{rn\_sbot\_min} and \np{rn\_sbot\_max}  
     763as the minimum and maximum depths at which the terrain-following vertical coordinate is calculated. 
     764 
     765Options for stretching the coordinate are provided as examples, but care must be taken to ensure  
     766that the vertical stretch used is appropriate for the application. 
     767 
     768The original default NEMO s-coordinate stretching is available if neither of the other options  
     769are specified as true (\np{ln\_s\_SH94}~=~false and \np{ln\_s\_SF12}~=~false).  
     770This uses a depth independent $\tanh$ function for the stretching \citep{Madec_al_JPO96}: 
    756771 
    757772\begin{equation} 
     
    760775\end{equation} 
    761776 
    762 where $s_{min}$ is the depth at which the s-coordinate stretching starts and allows a z-coordinate to placed on top of the stretched coordinate, and z is the depth (negative down from the asea surface). 
     777where $s_{min}$ is the depth at which the $s$-coordinate stretching starts and  
     778allows a $z$-coordinate to placed on top of the stretched coordinate,  
     779and $z$ is the depth (negative down from the asea surface). 
    763780 
    764781\begin{equation} 
     
    775792\end{equation} 
    776793 
    777 A stretching function, modified from the commonly used \citet{Song_Haidvogel_JCP94} stretching (\np{ln\_sco\_SH94}~=~true), is also available and is more commonly used for shelf seas modelling: 
     794A stretching function, modified from the commonly used \citet{Song_Haidvogel_JCP94}  
     795stretching (\np{ln\_s\_SH94}~=~true), is also available and is more commonly used for shelf seas modelling: 
    778796 
    779797\begin{equation} 
     
    785803%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    786804\begin{figure}[!ht]    \begin{center} 
    787 \includegraphics[width=1.0\textwidth]{./TexFiles/Figures/Fig_sco_function.pdf} 
     805\includegraphics[width=1.0\textwidth]{Fig_sco_function} 
    788806\caption{  \label{Fig_sco_function}    
    789807Examples of the stretching function applied to a seamount; from left to right:  
     
    792810%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    793811 
    794 where $H_c$ is the critical depth (\np{rn\_hc}) at which the coordinate transitions from pure $\sigma$ to the stretched coordinate,  and $\theta$ (\np{rn\_theta}) and $b$ (\np{rn\_bb}) are the surface and  
    795 bottom control parameters such that $0\leqslant \theta \leqslant 20$, and  
     812where $H_c$ is the critical depth (\np{rn\_hc}) at which the coordinate transitions from  
     813pure $\sigma$ to the stretched coordinate,  and $\theta$ (\np{rn\_theta}) and $b$ (\np{rn\_bb})  
     814are the surface and bottom control parameters such that $0\leqslant \theta \leqslant 20$, and  
    796815$0\leqslant b\leqslant 1$. $b$ has been designed to allow surface and/or bottom  
    797816increase of the vertical resolution (Fig.~\ref{Fig_sco_function}). 
    798817 
    799 Another example has been provided at version 3.5 (\np{ln\_sco\_SF12}) that allows a fixed surface resolution in an analytical terrain-following stretching \citet{Siddorn_Furner_OM12}. In this case the a stretching function $\gamma$ is defined such that: 
     818Another example has been provided at version 3.5 (\np{ln\_s\_SF12}) that allows  
     819a fixed surface resolution in an analytical terrain-following stretching \citet{Siddorn_Furner_OM12}.  
     820In this case the a stretching function $\gamma$ is defined such that: 
    800821 
    801822\begin{equation} 
     
    815836\end{equation} 
    816837 
    817 This gives an analytical stretching of $\sigma$ that is solvable in $A$ and $B$ as a function of the user prescribed stretching parameter $\alpha$ (\np{rn\_alpha}) that stretches towards the surface ($\alpha > 1.0$) or the bottom ($\alpha < 1.0$) and user prescribed surface (\np{rn\_zs}) and bottom depths. The bottom cell depth in this example is given as a function of water depth: 
     838This gives an analytical stretching of $\sigma$ that is solvable in $A$ and $B$ as a function of  
     839the user prescribed stretching parameter $\alpha$ (\np{rn\_alpha}) that stretches towards  
     840the surface ($\alpha > 1.0$) or the bottom ($\alpha < 1.0$) and user prescribed surface (\np{rn\_zs})  
     841and bottom depths. The bottom cell depth in this example is given as a function of water depth: 
    818842 
    819843\begin{equation} \label{DOM_zb} 
     
    825849%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
    826850\begin{figure}[!ht] 
    827    \includegraphics[width=1.0\textwidth]{./TexFiles/Figures/FIG_DOM_compare_coordinates_surface.pdf} 
     851   \includegraphics[width=1.0\textwidth]{FIG_DOM_compare_coordinates_surface} 
    828852        \caption{A comparison of the \citet{Song_Haidvogel_JCP94} $S$-coordinate (solid lines), a 50 level $Z$-coordinate (contoured surfaces) and the \citet{Siddorn_Furner_OM12} $S$-coordinate (dashed lines) in the surface 100m for a idealised bathymetry that goes from 50m to 5500m depth. For clarity every third coordinate surface is shown.} 
    829853    \label{fig_compare_coordinates_surface} 
     
    840864%        z*- or s*-coordinate 
    841865% ------------------------------------------------------------------------------------------------------------- 
    842 \subsection{$z^*$- or $s^*$-coordinate (add \key{vvl}) } 
    843 \label{DOM_zgr_vvl} 
    844  
    845 This option is described in the Report by Levier \textit{et al.} (2007), available on  
    846 the \NEMO web site.  
     866\subsection{$z^*$- or $s^*$-coordinate (\np{ln\_linssh}=false) } 
     867\label{DOM_zgr_star} 
     868 
     869This option is described in the Report by Levier \textit{et al.} (2007), available on the \NEMO web site.  
    847870 
    848871%gm% key advantage: minimise the diffusion/dispertion associated with advection in response to high frequency surface disturbances 
     
    860883gives the number of ocean levels ($i.e.$ those that are not masked) at each  
    861884$t$-point. mbathy is computed from the meter bathymetry using the definiton of  
    862 gdept as the number of $t$-points which gdept $\leq$ bathy.  
     885gdept as the number of $t$-points which gdept $\leq$ bathy. 
    863886 
    864887Modifications of the model bathymetry are performed in the \textit{bat\_ctl}  
     
    866889that do not communicate with another ocean point at the same level are eliminated. 
    867890 
    868 From the \textit{mbathy} array, the mask fields are defined as follows: 
     891As for the representation of bathymetry, a 2D integer array, misfdep, is created.  
     892misfdep defines the level of the first wet $t$-point. All the cells between $k=1$ and $misfdep(i,j)-1$ are masked.  
     893By default, misfdep(:,:)=1 and no cells are masked. 
     894 
     895In case of ice shelf cavities, modifications of the model bathymetry and ice shelf draft into  
     896the cavities are performed in the \textit{zgr\_isf} routine. The compatibility between ice shelf draft and bathymetry is checked.  
     897All the locations where the isf cavity is thinnest than \np{rn\_isfhmin} meters are grounded ($i.e.$ masked).  
     898If only one cell on the water column is opened at $t$-, $u$- or $v$-points, the bathymetry or the ice shelf draft is dug to fit this constrain. 
     899If the incompatibility is too strong (need to dig more than 1 cell), the cell is masked.\\  
     900 
     901From the \textit{mbathy} and \textit{misfdep} array, the mask fields are defined as follows: 
    869902\begin{align*} 
    870 tmask(i,j,k) &= \begin{cases}   \; 1&   \text{ if $k\leq mbathy(i,j)$  }    \\ 
    871                                                 \; 0&   \text{ if $k\leq mbathy(i,j)$  }    \end{cases}     \\ 
     903tmask(i,j,k) &= \begin{cases}   \; 0&   \text{ if $k < misfdep(i,j) $ } \\ 
     904                                \; 1&   \text{ if $misfdep(i,j) \leq k\leq mbathy(i,j)$  }    \\ 
     905                                \; 0&   \text{ if $k > mbathy(i,j)$  }    \end{cases}     \\ 
    872906umask(i,j,k) &=         \; tmask(i,j,k) \ * \ tmask(i+1,j,k)   \\ 
    873907vmask(i,j,k) &=         \; tmask(i,j,k) \ * \ tmask(i,j+1,k)   \\ 
    874908fmask(i,j,k) &=         \; tmask(i,j,k) \ * \ tmask(i+1,j,k)   \\ 
    875                    & \ \ \, * tmask(i,j,k) \ * \ tmask(i+1,j,k) 
     909             &    \ \ \, * tmask(i,j,k) \ * \ tmask(i+1,j,k) \\ 
     910wmask(i,j,k) &=         \; tmask(i,j,k) \ * \ tmask(i,j,k-1) \text{ with } wmask(i,j,1) = tmask(i,j,1)  
    876911\end{align*} 
    877912 
    878 Note that \textit{wmask} is not defined as it is exactly equal to \textit{tmask} with  
    879 the numerical indexing used (\S~\ref{DOM_Num_Index}). Moreover, the  
    880 specification of closed lateral boundaries requires that at least the first and last  
     913Note that, without ice shelves cavities, masks at $t-$ and $w-$points are identical with  
     914the numerical indexing used (\S~\ref{DOM_Num_Index}). Nevertheless, $wmask$ are required  
     915with oceean cavities to deal with the top boundary (ice shelf/ocean interface)  
     916exactly in the same way as for the bottom boundary.  
     917 
     918The specification of closed lateral boundaries requires that at least the first and last  
    881919rows and columns of the \textit{mbathy} array are set to zero. In the particular  
    882920case of an east-west cyclical boundary condition, \textit{mbathy} has its last  
     
    884922(and so too the mask arrays) (see \S~\ref{LBC_jperio}). 
    885923 
    886 %%% 
    887 \gmcomment{   \colorbox{yellow}{Add one word on tricky trick !} mbathy in further modified in zdfbfr{\ldots}.  } 
    888 %%% 
    889924 
    890925% ================================================================ 
     
    910945(typical of the tropical ocean), see \rou{istate\_t\_s} subroutine called from \mdl{istate} module. 
    911946\end{description} 
     947\end{document} 
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