Changeset 9392 for branches/2017/dev_merge_2017/DOC/tex_sub/chap_LDF.tex
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- 2018-03-09T16:57:00+01:00 (6 years ago)
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branches/2017/dev_merge_2017/DOC/tex_sub/chap_LDF.tex
r9389 r9392 25 25 Note that this chapter describes the standard implementation of iso-neutral 26 26 tracer mixing, and Griffies's implementation, which is used if 27 \ np{traldf\_grif}=true, is described in Appdx\ref{sec:triad}27 \forcode{traldf_grif = .true.}, is described in Appdx\ref{sec:triad} 28 28 29 29 %-----------------------------------nam_traldf - nam_dynldf-------------------------------------------- … … 46 46 A direction for lateral mixing has to be defined when the desired operator does 47 47 not act along the model levels. This occurs when $(a)$ horizontal mixing is 48 required on tracer or momentum (\np{ln \_traldf\_hor} or \np{ln\_dynldf\_hor})48 required on tracer or momentum (\np{ln_traldf_hor} or \np{ln_dynldf_hor}) 49 49 in $s$- or mixed $s$-$z$- coordinates, and $(b)$ isoneutral mixing is required 50 50 whatever the vertical coordinate is. This direction of mixing is defined by its … … 88 88 %gm% caution I'm not sure the simplification was a good idea! 89 89 90 These slopes are computed once in \rou{ldfslp\_init} when \ np{ln\_sco}=True,91 and either \ np{ln\_traldf\_hor}=True or \np{ln\_dynldf\_hor}=True.90 These slopes are computed once in \rou{ldfslp\_init} when \forcode{ln_sco = .true.}rue, 91 and either \forcode{ln_traldf_hor = .true.}rue or \forcode{ln_dynldf_hor = .true.}rue. 92 92 93 93 \subsection{Slopes for tracer iso-neutral mixing}\label{LDF_slp_iso} … … 147 147 \item[$s$- or hybrid $s$-$z$- coordinate : ] in the current release of \NEMO, 148 148 iso-neutral mixing is only employed for $s$-coordinates if the 149 Griffies scheme is used (\ np{traldf\_grif}=true; see Appdx \ref{sec:triad}).149 Griffies scheme is used (\forcode{traldf_grif = .true.}; see Appdx \ref{sec:triad}). 150 150 In other words, iso-neutral mixing will only be accurately represented with a 151 linear equation of state (\ np{nn\_eos}=1or 2). In the case of a "true" equation151 linear equation of state (\forcode{nn_eos = 1} or 2). In the case of a "true" equation 152 152 of state, the evaluation of $i$ and $j$ derivatives in \eqref{Eq_ldfslp_iso} 153 153 will include a pressure dependent part, leading to the wrong evaluation of … … 212 212 ocean model are modified \citep{Weaver_Eby_JPO97, 213 213 Griffies_al_JPO98}. Griffies's scheme is now available in \NEMO if 214 \np{traldf \_grif\_iso} is set true; see Appdx \ref{sec:triad}. Here,214 \np{traldf_grif_iso} is set true; see Appdx \ref{sec:triad}. Here, 215 215 another strategy is presented \citep{Lazar_PhD97}: a local 216 216 filtering of the iso-neutral slopes (made on 9 grid-points) prevents … … 347 347 When none of the \textbf{key\_dynldf\_...} and \textbf{key\_traldf\_...} keys are 348 348 defined, a constant value is used over the whole ocean for momentum and 349 tracers, which is specified through the \np{rn \_ahm0} and \np{rn\_aht0} namelist349 tracers, which is specified through the \np{rn_ahm0} and \np{rn_aht0} namelist 350 350 parameters. 351 351 … … 356 356 mixing coefficients will require 3D arrays. In the 1D option, a hyperbolic variation 357 357 of the lateral mixing coefficient is introduced in which the surface value is 358 \np{rn \_aht0} (\np{rn\_ahm0}), the bottom value is 1/4 of the surface value,358 \np{rn_aht0} (\np{rn_ahm0}), the bottom value is 1/4 of the surface value, 359 359 and the transition takes place around z=300~m with a width of 300~m 360 360 ($i.e.$ both the depth and the width of the inflection point are set to 300~m). … … 372 372 \end{equation} 373 373 where $e_{max}$ is the maximum of $e_1$ and $e_2$ taken over the whole masked 374 ocean domain, and $A_o^l$ is the \np{rn \_ahm0} (momentum) or \np{rn\_aht0} (tracer)374 ocean domain, and $A_o^l$ is the \np{rn_ahm0} (momentum) or \np{rn_aht0} (tracer) 375 375 namelist parameter. This variation is intended to reflect the lesser need for subgrid 376 376 scale eddy mixing where the grid size is smaller in the domain. It was introduced in … … 384 384 Other formulations can be introduced by the user for a given configuration. 385 385 For example, in the ORCA2 global ocean model (see Configurations), the laplacian 386 viscosity operator uses \np{rn \_ahm0}~= 4.10$^4$ m$^2$/s poleward of 20$^{\circ}$387 north and south and decreases linearly to \np{rn \_aht0}~= 2.10$^3$ m$^2$/s386 viscosity operator uses \np{rn_ahm0}~= 4.10$^4$ m$^2$/s poleward of 20$^{\circ}$ 387 north and south and decreases linearly to \np{rn_aht0}~= 2.10$^3$ m$^2$/s 388 388 at the equator \citep{Madec_al_JPO96, Delecluse_Madec_Bk00}. This modification 389 389 can be found in routine \rou{ldf\_dyn\_c2d\_orca} defined in \mdl{ldfdyn\_c2d}. … … 423 423 (3) for isopycnal diffusion on momentum or tracers, an additional purely 424 424 horizontal background diffusion with uniform coefficient can be added by 425 setting a non zero value of \np{rn \_ahmb0} or \np{rn\_ahtb0}, a background horizontal425 setting a non zero value of \np{rn_ahmb0} or \np{rn_ahtb0}, a background horizontal 426 426 eddy viscosity or diffusivity coefficient (namelist parameters whose default 427 427 values are $0$). However, the technique used to compute the isopycnal … … 438 438 (6) it is possible to use both the laplacian and biharmonic operators concurrently. 439 439 440 (7) it is possible to run without explicit lateral diffusion on momentum (\np{ln \_dynldf\_lap} =441 \np{ln \_dynldf\_bilap} = false). This is recommended when using the UBS advection442 scheme on momentum (\np{ln \_dynadv\_ubs} = true, see \ref{DYN_adv_ubs})440 (7) it is possible to run without explicit lateral diffusion on momentum (\np{ln_dynldf_lap} = 441 \np{ln_dynldf_bilap} = false). This is recommended when using the UBS advection 442 scheme on momentum (\np{ln_dynadv_ubs} = true, see \ref{DYN_adv_ubs}) 443 443 and can be useful for testing purposes. 444 444 … … 455 455 described in \S\ref{LDF_coef}. If none of the keys \key{traldf\_cNd}, 456 456 N=1,2,3 is set (the default), spatially constant iso-neutral $A_l$ and 457 GM diffusivity $A_e$ are directly set by \np{rn \_aeih\_0} and458 \np{rn \_aeiv\_0}. If 2D-varying coefficients are set with457 GM diffusivity $A_e$ are directly set by \np{rn_aeih_0} and 458 \np{rn_aeiv_0}. If 2D-varying coefficients are set with 459 459 \key{traldf\_c2d} then $A_l$ is reduced in proportion with horizontal 460 460 scale factor according to \eqref{Eq_title} \footnote{Except in global ORCA … … 467 467 case, $A_e$ at low latitudes $|\theta|<20^{\circ}$ is further 468 468 reduced by a factor $|f/f_{20}|$, where $f_{20}$ is the value of $f$ 469 at $20^{\circ}$~N} (\mdl{ldfeiv}) and \np{rn \_aeiv\_0} is ignored469 at $20^{\circ}$~N} (\mdl{ldfeiv}) and \np{rn_aeiv_0} is ignored 470 470 unless it is zero. 471 471 } … … 485 485 \end{equation} 486 486 where $A^{eiv}$ is the eddy induced velocity coefficient whose value is set 487 through \np{rn \_aeiv}, a \textit{nam\_traldf} namelist parameter.487 through \np{rn_aeiv}, a \textit{nam\_traldf} namelist parameter. 488 488 The three components of the eddy induced velocity are computed and add 489 489 to the eulerian velocity in \mdl{traadv\_eiv}. This has been preferred to a
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