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branches/2017/dev_CNRS_2017/DOC/TexFiles/Chapters/Chap_DOM.tex
r8938 r8969 406 406 407 407 408 CAUTION! This part need to be rewritten! no jphgr\_mesh anymore409 410 The user has three options available in defining a horizontal grid, which involve411 the namelist variable \np{jphgr\_mesh} of the \ngn{namcfg} namelist.412 \begin{description}413 \item[\np{jphgr\_mesh}=0] The most general curvilinear orthogonal grids.414 The coordinates and their first derivatives with respect to $i$ and $j$ are provided415 in a input file (\ifile{coordinates}), read in \rou{hgr\_read} subroutine of the domhgr module.416 \item[\np{jphgr\_mesh}=1 to 5] A few simple analytical grids are provided (see below).417 For other analytical grids, the \mdl{domhgr} module must be modified by the user.418 \end{description}419 420 There are two simple cases of geographical grids on the sphere. With421 \np{jphgr\_mesh}=1, the grid (expressed in degrees) is regular in space,422 with grid sizes specified by parameters \np{ppe1\_deg} and \np{ppe2\_deg},423 respectively. Such a geographical grid can be very anisotropic at high latitudes424 because of the convergence of meridians (the zonal scale factors $e_1$425 become much smaller than the meridional scale factors $e_2$). The Mercator426 grid (\np{jphgr\_mesh}=4) avoids this anisotropy by refining the meridional scale427 factors in the same way as the zonal ones. In this case, meridional scale factors428 and latitudes are calculated analytically using the formulae appropriate for429 a Mercator projection, based on \np{ppe1\_deg} which is a reference grid spacing430 at the equator (this applies even when the geographical equator is situated outside431 the model domain).432 %%%433 \gmcomment{ give here the analytical expression of the Mercator mesh}434 %%%435 In these two cases (\np{jphgr\_mesh}=1 or 4), the grid position is defined by the436 longitude and latitude of the south-westernmost point (\np{ppglamt0}437 and \np{ppgphi0}). Note that for the Mercator grid the user need only provide438 an approximate starting latitude: the real latitude will be recalculated analytically,439 in order to ensure that the equator corresponds to line passing through $t$-440 and $u$-points.441 442 Rectangular grids ignoring the spherical geometry are defined with443 \np{jphgr\_mesh} = 2, 3, 5. The domain is either an $f$-plane (\np{jphgr\_mesh} = 2,444 Coriolis factor is constant) or a beta-plane (\np{jphgr\_mesh} = 3, the Coriolis factor445 is linear in the $j$-direction). The grid size is uniform in meter in each direction,446 and given by the parameters \np{ppe1\_m} and \np{ppe2\_m} respectively.447 The zonal grid coordinate (\textit{glam} arrays) is in kilometers, starting at zero448 with the first $t$-point. The meridional coordinate (gphi. arrays) is in kilometers,449 and the second $t$-point corresponds to coordinate $gphit=0$. The input450 variable \np{ppglam0} is ignored. \np{ppgphi0} is used to set the reference451 latitude for computation of the Coriolis parameter. In the case of the beta plane,452 \np{ppgphi0} corresponds to the center of the domain. Finally, the special case453 \np{jphgr\_mesh}=5 corresponds to a beta plane in a rotated domain for the454 GYRE configuration, representing a classical mid-latitude double gyre system.455 The rotation allows us to maximize the jet length relative to the gyre areas456 (and the number of grid points).457 458 The choice of the grid must be consistent with the boundary conditions specified459 by \np{jperio}, a parameter found in \ngn{namcfg} namelist (see {\S\ref{LBC}).460 461 408 % ------------------------------------------------------------------------------------------------------------- 462 409 % Grid files … … 646 593 (Fig.~\ref{Fig_zgr}). 647 594 648 If the ice shelf cavities are opened (\np{ln\_isfcav}=~true~ }), the definition of $z_0$ is the same.595 If the ice shelf cavities are opened (\np{ln\_isfcav}=~true~), the definition of $z_0$ is the same. 649 596 However, definition of $e_3^0$ at $t$- and $w$-points is respectively changed to: 650 597 \begin{equation} \label{DOM_zgr_ana}
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