Changeset 6140 for trunk/DOC/TexFiles/Chapters/Chap_DOM.tex
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- 2015-12-21T12:35:23+01:00 (8 years ago)
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trunk/DOC/TexFiles/Chapters/Chap_DOM.tex (modified) (6 diffs)
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trunk/DOC/TexFiles/Chapters/Chap_DOM.tex
r5120 r6140 1 1 % ================================================================ 2 % Chapter 2 �Space and Time Domain (DOM)2 % Chapter 2 ——— Space and Time Domain (DOM) 3 3 % ================================================================ 4 4 \chapter{Space Domain (DOM) } … … 364 364 For both grids here, the same $w$-point depth has been chosen but in (a) the 365 365 $t$-points are set half way between $w$-points while in (b) they are defined from 366 an analytical function: $z(k)=5\,( i-1/2)^3 - 45\,(i-1/2)^2 + 140\,(i-1/2) - 150$.366 an analytical function: $z(k)=5\,(k-1/2)^3 - 45\,(k-1/2)^2 + 140\,(k-1/2) - 150$. 367 367 Note the resulting difference between the value of the grid-size $\Delta_k$ and 368 368 those of the scale factor $e_k$. } … … 475 475 (d) hybrid $s-z$ coordinate, 476 476 (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 the477 (f) same as (e) but in the non-linear free surface (\np{ln\_linssh}=false). 478 Note that the non-linear free surface can be used with any of the 479 479 5 coordinates (a) to (e).} 480 480 \end{center} \end{figure} 481 481 %>>>>>>>>>>>>>>>>>>>>>>>>>>>> 482 482 483 The choice of a vertical coordinate, even if it is made through a namelist parameter,483 The choice of a vertical coordinate, even if it is made through \ngn{namzgr} namelist parameters, 484 484 must be done once of all at the beginning of an experiment. It is not intended as an 485 485 option which can be enabled or disabled in the middle of an experiment. Three main … … 488 488 (\np{ln\_zps}~=~true), or generalized, $s$-coordinate (\np{ln\_sco}~=~true). 489 489 Hybridation 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). 490 (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: 491 the coordinate follow the time-variation of the free surface so that the transformation is time dependent: 492 $z(i,j,k,t)$ (Fig.~\ref{Fig_z_zps_s_sps}f). When a linear free surface is assumed (\np{ln\_linssh}=true), 493 the vertical coordinate are fixed in time, but the seawater can move up and down across the z=0 surface 494 (in other words, the top of the ocean in not a rigid-lid). 495 The last choice in terms of vertical coordinate concerns the presence (or not) in the model domain 496 of ocean cavities beneath ice shelves. Setting \np{ln\_isfcav} to true allows to manage ocean cavities, 497 otherwise they are filled in. 497 498 498 499 Contrary to the horizontal grid, the vertical grid is computed in the code and no 499 500 provision is made for reading it from a file. The only input file is the bathymetry 500 (in meters) (\ifile{bathy\_meter}) 501 (in meters) (\ifile{bathy\_meter}). 501 502 \footnote{N.B. in full step $z$-coordinate, a \ifile{bathy\_level} file can replace the 502 503 \ifile{bathy\_meter} file, so that the computation of the number of wet ocean point 503 504 in each water column is by-passed}. 505 If \np{ln\_isfcav}~=~true, an extra file input file describing the ice shelf draft 506 (in meters) (\ifile{isf\_draft\_meter}) is needed and all the location where the isf cavity thinnest 507 than \np{rn\_isfhmin} meters are grounded (ie masked). 508 504 509 After reading the bathymetry, the algorithm for vertical grid definition differs 505 510 between the different options: … … 519 524 %%% 520 525 521 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). 526 Unless a linear free surface is used (\np{ln\_linssh}=false), the arrays describing 527 the grid point depths and vertical scale factors are three set of three dimensional arrays $(i,j,k)$ 528 defined at \textit{before}, \textit{now} and \textit{after} time step. The time at which they are 529 defined is indicated by a suffix:$\_b$, $\_n$, or $\_a$, respectively. They are updated at each model time step 530 using a fixed reference coordinate system which computer names have a $\_0$ suffix. 531 When the linear free surface option is used (\np{ln\_linssh}=true), \textit{before}, \textit{now} 532 and \textit{after} arrays are simply set one for all to their reference counterpart. 533 534 534 535 535 % ------------------------------------------------------------------------------------------------------------- … … 840 840 % z*- or s*-coordinate 841 841 % ------------------------------------------------------------------------------------------------------------- 842 \subsection{$z^*$- or $s^*$-coordinate ( add \key{vvl}) }843 \label{DOM_zgr_ vvl}842 \subsection{$z^*$- or $s^*$-coordinate (\np{ln\_linssh}=false) } 843 \label{DOM_zgr_star} 844 844 845 845 This option is described in the Report by Levier \textit{et al.} (2007), available on
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