Changeset 11577 for NEMO/trunk/doc/latex/NEMO/subfiles/chap_DYN.tex
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NEMO/trunk/doc/latex/NEMO/subfiles/chap_DYN.tex
r11571 r11577 176 176 applications of the \NEMO\ ocean model. 177 177 The flux form option (see next section) has been present since version $2$. 178 Options are defined through the \nam{dyn \_adv} namelist variables Coriolis and178 Options are defined through the \nam{dyn_adv}{dyn\_adv} namelist variables Coriolis and 179 179 momentum advection terms are evaluated using a leapfrog scheme, 180 180 \ie\ the velocity appearing in these expressions is centred in time (\textit{now} velocity). … … 196 196 %------------------------------------------------------------------------------------------------------------- 197 197 198 Options are defined through the \nam{dyn \_vor} namelist variables.198 Options are defined through the \nam{dyn_vor}{dyn\_vor} namelist variables. 199 199 Four discretisations of the vorticity term (\texttt{ln\_dynvor\_xxx}\forcode{=.true.}) are available: 200 200 conserving potential enstrophy of horizontally non-divergent flow (ENS scheme); … … 205 205 (EEN scheme) (see \autoref{subsec:INVARIANTS_vorEEN}). 206 206 In the case of ENS, ENE or MIX schemes the land sea mask may be slightly modified to ensure the consistency of 207 vorticity term with analytical equations (\np{ln \_dynvor\_con}\forcode{=.true.}).207 vorticity term with analytical equations (\np{ln_dynvor_con}{ln\_dynvor\_con}\forcode{=.true.}). 208 208 The vorticity terms are all computed in dedicated routines that can be found in the \mdl{dynvor} module. 209 209 … … 211 211 % enstrophy conserving scheme 212 212 %------------------------------------------------------------- 213 \subsubsection[Enstrophy conserving scheme (\forcode{ln_dynvor_ens})]{Enstrophy conserving scheme (\protect\np{ln \_dynvor\_ens})}213 \subsubsection[Enstrophy conserving scheme (\forcode{ln_dynvor_ens})]{Enstrophy conserving scheme (\protect\np{ln_dynvor_ens}{ln\_dynvor\_ens})} 214 214 \label{subsec:DYN_vor_ens} 215 215 … … 234 234 % energy conserving scheme 235 235 %------------------------------------------------------------- 236 \subsubsection[Energy conserving scheme (\forcode{ln_dynvor_ene})]{Energy conserving scheme (\protect\np{ln \_dynvor\_ene})}236 \subsubsection[Energy conserving scheme (\forcode{ln_dynvor_ene})]{Energy conserving scheme (\protect\np{ln_dynvor_ene}{ln\_dynvor\_ene})} 237 237 \label{subsec:DYN_vor_ene} 238 238 … … 254 254 % mix energy/enstrophy conserving scheme 255 255 %------------------------------------------------------------- 256 \subsubsection[Mixed energy/enstrophy conserving scheme (\forcode{ln_dynvor_mix})]{Mixed energy/enstrophy conserving scheme (\protect\np{ln \_dynvor\_mix})}256 \subsubsection[Mixed energy/enstrophy conserving scheme (\forcode{ln_dynvor_mix})]{Mixed energy/enstrophy conserving scheme (\protect\np{ln_dynvor_mix}{ln\_dynvor\_mix})} 257 257 \label{subsec:DYN_vor_mix} 258 258 … … 279 279 % energy and enstrophy conserving scheme 280 280 %------------------------------------------------------------- 281 \subsubsection[Energy and enstrophy conserving scheme (\forcode{ln_dynvor_een})]{Energy and enstrophy conserving scheme (\protect\np{ln \_dynvor\_een})}281 \subsubsection[Energy and enstrophy conserving scheme (\forcode{ln_dynvor_een})]{Energy and enstrophy conserving scheme (\protect\np{ln_dynvor_een}{ln\_dynvor\_een})} 282 282 \label{subsec:DYN_vor_een} 283 283 … … 327 327 A key point in \autoref{eq:DYN_een_e3f} is how the averaging in the \textbf{i}- and \textbf{j}- directions is made. 328 328 It uses the sum of masked t-point vertical scale factor divided either by the sum of the four t-point masks 329 (\np{nn \_een\_e3f}\forcode{=1}), or just by $4$ (\np{nn\_een\_e3f}\forcode{=.true.}).329 (\np{nn_een_e3f}{nn\_een\_e3f}\forcode{=1}), or just by $4$ (\np{nn\_een\_e3f}\forcode{=.true.}). 330 330 The latter case preserves the continuity of $e_{3f}$ when one or more of the neighbouring $e_{3t}$ tends to zero and 331 331 extends by continuity the value of $e_{3f}$ into the land areas. … … 407 407 \right. 408 408 \] 409 When \np{ln \_dynzad\_zts}\forcode{=.true.},409 When \np{ln_dynzad_zts}{ln\_dynzad\_zts}\forcode{=.true.}, 410 410 a split-explicit time stepping with 5 sub-timesteps is used on the vertical advection term. 411 411 This option can be useful when the value of the timestep is limited by vertical advection \citep{lemarie.debreu.ea_OM15}. 412 412 Note that in this case, 413 413 a similar split-explicit time stepping should be used on vertical advection of tracer to ensure a better stability, 414 an option which is only available with a TVD scheme (see \np{ln \_traadv\_tvd\_zts} in \autoref{subsec:TRA_adv_tvd}).414 an option which is only available with a TVD scheme (see \np{ln_traadv_tvd_zts}{ln\_traadv\_tvd\_zts} in \autoref{subsec:TRA_adv_tvd}). 415 415 416 416 … … 424 424 %------------------------------------------------------------------------------------------------------------- 425 425 426 Options are defined through the \nam{dyn \_adv} namelist variables.426 Options are defined through the \nam{dyn_adv}{dyn\_adv} namelist variables. 427 427 In the flux form (as in the vector invariant form), 428 428 the Coriolis and momentum advection terms are evaluated using a leapfrog scheme, … … 481 481 or a $3^{rd}$ order upstream biased scheme, UBS. 482 482 The latter is described in \citet{shchepetkin.mcwilliams_OM05}. 483 The schemes are selected using the namelist logicals \np{ln \_dynadv\_cen2} and \np{ln\_dynadv\_ubs}.483 The schemes are selected using the namelist logicals \np{ln_dynadv_cen2}{ln\_dynadv\_cen2} and \np{ln_dynadv_ubs}{ln\_dynadv\_ubs}. 484 484 In flux form, the schemes differ by the choice of a space and time interpolation to define the value of 485 485 $u$ and $v$ at the centre of each face of $u$- and $v$-cells, \ie\ at the $T$-, $f$-, … … 489 489 % 2nd order centred scheme 490 490 %------------------------------------------------------------- 491 \subsubsection[CEN2: $2^{nd}$ order centred scheme (\forcode{ln_dynadv_cen2})]{CEN2: $2^{nd}$ order centred scheme (\protect\np{ln \_dynadv\_cen2})}491 \subsubsection[CEN2: $2^{nd}$ order centred scheme (\forcode{ln_dynadv_cen2})]{CEN2: $2^{nd}$ order centred scheme (\protect\np{ln_dynadv_cen2}{ln\_dynadv\_cen2})} 492 492 \label{subsec:DYN_adv_cen2} 493 493 … … 512 512 % UBS scheme 513 513 %------------------------------------------------------------- 514 \subsubsection[UBS: Upstream Biased Scheme (\forcode{ln_dynadv_ubs})]{UBS: Upstream Biased Scheme (\protect\np{ln \_dynadv\_ubs})}514 \subsubsection[UBS: Upstream Biased Scheme (\forcode{ln_dynadv_ubs})]{UBS: Upstream Biased Scheme (\protect\np{ln_dynadv_ubs}{ln\_dynadv\_ubs})} 515 515 \label{subsec:DYN_adv_ubs} 516 516 … … 534 534 But the amplitudes of the false extrema are significantly reduced over those in the centred second order method. 535 535 As the scheme already includes a diffusion component, it can be used without explicit lateral diffusion on momentum 536 (\ie\ \np{ln \_dynldf\_lap}\forcode{=}\np{ln\_dynldf\_bilap}\forcode{=.false.}),536 (\ie\ \np{ln_dynldf_lap}{ln\_dynldf\_lap}\forcode{=}\np{ln_dynldf_bilap}{ln\_dynldf\_bilap}\forcode{=.false.}), 537 537 and it is recommended to do so. 538 538 … … 576 576 %------------------------------------------------------------------------------------------------------------- 577 577 578 Options are defined through the \nam{dyn \_hpg} namelist variables.578 Options are defined through the \nam{dyn_hpg}{dyn\_hpg} namelist variables. 579 579 The key distinction between the different algorithms used for 580 580 the hydrostatic pressure gradient is the vertical coordinate used, … … 591 591 % z-coordinate with full step 592 592 %-------------------------------------------------------------------------------------------------------------- 593 \subsection[Full step $Z$-coordinate (\forcode{ln_dynhpg_zco})]{Full step $Z$-coordinate (\protect\np{ln \_dynhpg\_zco})}593 \subsection[Full step $Z$-coordinate (\forcode{ln_dynhpg_zco})]{Full step $Z$-coordinate (\protect\np{ln_dynhpg_zco}{ln\_dynhpg\_zco})} 594 594 \label{subsec:DYN_hpg_zco} 595 595 … … 636 636 % z-coordinate with partial step 637 637 %-------------------------------------------------------------------------------------------------------------- 638 \subsection[Partial step $Z$-coordinate (\forcode{ln_dynhpg_zps})]{Partial step $Z$-coordinate (\protect\np{ln \_dynhpg\_zps})}638 \subsection[Partial step $Z$-coordinate (\forcode{ln_dynhpg_zps})]{Partial step $Z$-coordinate (\protect\np{ln_dynhpg_zps}{ln\_dynhpg\_zps})} 639 639 \label{subsec:DYN_hpg_zps} 640 640 … … 665 665 density Jacobian with cubic polynomial method is currently disabled whilst known bugs are under investigation. 666 666 667 $\bullet$ Traditional coding (see for example \citet{madec.delecluse.ea_JPO96}: (\np{ln \_dynhpg\_sco}\forcode{=.true.})667 $\bullet$ Traditional coding (see for example \citet{madec.delecluse.ea_JPO96}: (\np{ln_dynhpg_sco}{ln\_dynhpg\_sco}\forcode{=.true.}) 668 668 \begin{equation} 669 669 \label{eq:DYN_hpg_sco} … … 683 683 ($e_{3w}$). 684 684 685 $\bullet$ Traditional coding with adaptation for ice shelf cavities (\np{ln \_dynhpg\_isf}\forcode{=.true.}).686 This scheme need the activation of ice shelf cavities (\np{ln \_isfcav}\forcode{=.true.}).687 688 $\bullet$ Pressure Jacobian scheme (prj) (a research paper in preparation) (\np{ln \_dynhpg\_prj}\forcode{=.true.})685 $\bullet$ Traditional coding with adaptation for ice shelf cavities (\np{ln_dynhpg_isf}{ln\_dynhpg\_isf}\forcode{=.true.}). 686 This scheme need the activation of ice shelf cavities (\np{ln_isfcav}{ln\_isfcav}\forcode{=.true.}). 687 688 $\bullet$ Pressure Jacobian scheme (prj) (a research paper in preparation) (\np{ln_dynhpg_prj}{ln\_dynhpg\_prj}\forcode{=.true.}) 689 689 690 690 $\bullet$ Density Jacobian with cubic polynomial scheme (DJC) \citep{shchepetkin.mcwilliams_OM05} 691 (\np{ln \_dynhpg\_djc}\forcode{=.true.}) (currently disabled; under development)691 (\np{ln_dynhpg_djc}{ln\_dynhpg\_djc}\forcode{=.true.}) (currently disabled; under development) 692 692 693 693 Note that expression \autoref{eq:DYN_hpg_sco} is commonly used when the variable volume formulation is activated 694 694 (\texttt{vvl?}) because in that case, even with a flat bottom, 695 695 the coordinate surfaces are not horizontal but follow the free surface \citep{levier.treguier.ea_rpt07}. 696 The pressure jacobian scheme (\np{ln \_dynhpg\_prj}\forcode{=.true.}) is available as697 an improved option to \np{ln \_dynhpg\_sco}\forcode{=.true.} when \texttt{vvl?} is active.696 The pressure jacobian scheme (\np{ln_dynhpg_prj}{ln\_dynhpg\_prj}\forcode{=.true.}) is available as 697 an improved option to \np{ln_dynhpg_sco}{ln\_dynhpg\_sco}\forcode{=.true.} when \texttt{vvl?} is active. 698 698 The pressure Jacobian scheme uses a constrained cubic spline to 699 699 reconstruct the density profile across the water column. … … 707 707 708 708 Beneath an ice shelf, the total pressure gradient is the sum of the pressure gradient due to the ice shelf load and 709 the pressure gradient due to the ocean load (\np{ln \_dynhpg\_isf}\forcode{=.true.}).\\709 the pressure gradient due to the ocean load (\np{ln_dynhpg_isf}{ln\_dynhpg\_isf}\forcode{=.true.}).\\ 710 710 711 711 The main hypothesis to compute the ice shelf load is that the ice shelf is in an isostatic equilibrium. … … 722 722 % Time-scheme 723 723 %-------------------------------------------------------------------------------------------------------------- 724 \subsection[Time-scheme (\forcode{ln_dynhpg_imp})]{Time-scheme (\protect\np{ln \_dynhpg\_imp})}724 \subsection[Time-scheme (\forcode{ln_dynhpg_imp})]{Time-scheme (\protect\np{ln_dynhpg_imp}{ln\_dynhpg\_imp})} 725 725 \label{subsec:DYN_hpg_imp} 726 726 … … 738 738 rather than at the central time level $t$ only, as in the standard leapfrog scheme. 739 739 740 $\bullet$ leapfrog scheme (\np{ln \_dynhpg\_imp}\forcode{=.true.}):740 $\bullet$ leapfrog scheme (\np{ln_dynhpg_imp}{ln\_dynhpg\_imp}\forcode{=.true.}): 741 741 742 742 \begin{equation} … … 746 746 \end{equation} 747 747 748 $\bullet$ semi-implicit scheme (\np{ln \_dynhpg\_imp}\forcode{=.true.}):748 $\bullet$ semi-implicit scheme (\np{ln_dynhpg_imp}{ln\_dynhpg\_imp}\forcode{=.true.}): 749 749 \begin{equation} 750 750 \label{eq:DYN_hpg_imp} … … 764 764 such as the stability limits associated with advection or diffusion. 765 765 766 In practice, the semi-implicit scheme is used when \np{ln \_dynhpg\_imp}\forcode{=.true.}.766 In practice, the semi-implicit scheme is used when \np{ln_dynhpg_imp}{ln\_dynhpg\_imp}\forcode{=.true.}. 767 767 In this case, we choose to apply the time filter to temperature and salinity used in the equation of state, 768 768 instead of applying it to the hydrostatic pressure or to the density, … … 778 778 Note that in the semi-implicit case, it is necessary to save the filtered density, 779 779 an extra three-dimensional field, in the restart file to restart the model with exact reproducibility. 780 This option is controlled by \np{nn \_dynhpg\_rst}, a namelist parameter.780 This option is controlled by \np{nn_dynhpg_rst}{nn\_dynhpg\_rst}, a namelist parameter. 781 781 782 782 % ================================================================ … … 794 794 %------------------------------------------------------------------------------------------------------------ 795 795 796 Options are defined through the \nam{dyn \_spg} namelist variables.796 Options are defined through the \nam{dyn_spg}{dyn\_spg} namelist variables. 797 797 The surface pressure gradient term is related to the representation of the free surface (\autoref{sec:MB_hor_pg}). 798 798 The main distinction is between the fixed volume case (linear free surface) and … … 825 825 % Explicit free surface formulation 826 826 %-------------------------------------------------------------------------------------------------------------- 827 \subsection[Explicit free surface (\forcode{ln_dynspg_exp})]{Explicit free surface (\protect\np{ln \_dynspg\_exp})}827 \subsection[Explicit free surface (\forcode{ln_dynspg_exp})]{Explicit free surface (\protect\np{ln_dynspg_exp}{ln\_dynspg\_exp})} 828 828 \label{subsec:DYN_spg_exp} 829 829 830 In the explicit free surface formulation (\np{ln \_dynspg\_exp} set to true),830 In the explicit free surface formulation (\np{ln_dynspg_exp}{ln\_dynspg\_exp} set to true), 831 831 the model time step is chosen to be small enough to resolve the external gravity waves 832 832 (typically a few tens of seconds). … … 851 851 % Split-explict free surface formulation 852 852 %-------------------------------------------------------------------------------------------------------------- 853 \subsection[Split-explicit free surface (\forcode{ln_dynspg_ts})]{Split-explicit free surface (\protect\np{ln \_dynspg\_ts})}853 \subsection[Split-explicit free surface (\forcode{ln_dynspg_ts})]{Split-explicit free surface (\protect\np{ln_dynspg_ts}{ln\_dynspg\_ts})} 854 854 \label{subsec:DYN_spg_ts} 855 855 %------------------------------------------namsplit----------------------------------------------------------- … … 858 858 %------------------------------------------------------------------------------------------------------------- 859 859 860 The split-explicit free surface formulation used in \NEMO\ (\np{ln \_dynspg\_ts} set to true),860 The split-explicit free surface formulation used in \NEMO\ (\np{ln_dynspg_ts}{ln\_dynspg\_ts} set to true), 861 861 also called the time-splitting formulation, follows the one proposed by \citet{shchepetkin.mcwilliams_OM05}. 862 862 The general idea is to solve the free surface equation and the associated barotropic velocity equations with … … 864 864 (\autoref{fig:DYN_spg_ts}). 865 865 The size of the small time step, $\rdt_e$ (the external mode or barotropic time step) is provided through 866 the \np{nn \_baro} namelist parameter as: $\rdt_e = \rdt / nn\_baro$.867 This parameter can be optionally defined automatically (\np{ln \_bt\_nn\_auto}\forcode{=.true.}) considering that866 the \np{nn_baro}{nn\_baro} namelist parameter as: $\rdt_e = \rdt / nn\_baro$. 867 This parameter can be optionally defined automatically (\np{ln_bt_nn_auto}{ln\_bt\_nn\_auto}\forcode{=.true.}) considering that 868 868 the stability of the barotropic system is essentially controled by external waves propagation. 869 869 Maximum Courant number is in that case time independent, and easily computed online from the input bathymetry. 870 Therefore, $\rdt_e$ is adjusted so that the Maximum allowed Courant number is smaller than \np{rn \_bt\_cmax}.870 Therefore, $\rdt_e$ is adjusted so that the Maximum allowed Courant number is smaller than \np{rn_bt_cmax}{rn\_bt\_cmax}. 871 871 872 872 %%% … … 903 903 Time increases to the right. 904 904 In this particular exemple, 905 a boxcar averaging window over \np{nn \_baro} barotropic time steps is used906 (\np{nn\_bt\_flt}\forcode{=1}) and \np{nn \_baro}\forcode{=5}.905 a boxcar averaging window over \np{nn_baro}{nn\_baro} barotropic time steps is used 906 (\np{nn\_bt\_flt}\forcode{=1}) and \np{nn_baro}{nn\_baro}\forcode{=5}. 907 907 Internal mode time steps (which are also the model time steps) are denoted by 908 908 $t-\rdt$, $t$ and $t+\rdt$. … … 913 913 the latter are used to obtain time averaged transports to advect tracers. 914 914 a) Forward time integration: 915 \protect\np{ln \_bt\_fw}\forcode{=.true.}, \protect\np{ln\_bt\_av}\forcode{=.true.}.915 \protect\np{ln_bt_fw}{ln\_bt\_fw}\forcode{=.true.}, \protect\np{ln_bt_av}{ln\_bt\_av}\forcode{=.true.}. 916 916 b) Centred time integration: 917 \protect\np{ln \_bt\_fw}\forcode{=.false.}, \protect\np{ln\_bt\_av}\forcode{=.true.}.917 \protect\np{ln_bt_fw}{ln\_bt\_fw}\forcode{=.false.}, \protect\np{ln_bt_av}{ln\_bt\_av}\forcode{=.true.}. 918 918 c) Forward time integration with no time filtering (POM-like scheme): 919 \protect\np{ln \_bt\_fw}\forcode{=.true.}, \protect\np{ln\_bt\_av}\forcode{=.false.}.}919 \protect\np{ln_bt_fw}{ln\_bt\_fw}\forcode{=.true.}, \protect\np{ln_bt_av}{ln\_bt\_av}\forcode{=.false.}.} 920 920 \label{fig:DYN_spg_ts} 921 921 \end{figure} 922 922 %> > > > > > > > > > > > > > > > > > > > > > > > > > > > 923 923 924 In the default case (\np{ln \_bt\_fw}\forcode{=.true.}),924 In the default case (\np{ln_bt_fw}{ln\_bt\_fw}\forcode{=.true.}), 925 925 the external mode is integrated between \textit{now} and \textit{after} baroclinic time-steps 926 926 (\autoref{fig:DYN_spg_ts}a). 927 927 To avoid aliasing of fast barotropic motions into three dimensional equations, 928 time filtering is eventually applied on barotropic quantities (\np{ln \_bt\_av}\forcode{=.true.}).928 time filtering is eventually applied on barotropic quantities (\np{ln_bt_av}{ln\_bt\_av}\forcode{=.true.}). 929 929 In that case, the integration is extended slightly beyond \textit{after} time step to 930 930 provide time filtered quantities. … … 933 933 asselin filtering is not applied to barotropic quantities.\\ 934 934 Alternatively, one can choose to integrate barotropic equations starting from \textit{before} time step 935 (\np{ln \_bt\_fw}\forcode{=.false.}).936 Although more computationaly expensive ( \np{nn \_baro} additional iterations are indeed necessary),935 (\np{ln_bt_fw}{ln\_bt\_fw}\forcode{=.false.}). 936 Although more computationaly expensive ( \np{nn_baro}{nn\_baro} additional iterations are indeed necessary), 937 937 the baroclinic to barotropic forcing term given at \textit{now} time step become centred in 938 938 the middle of the integration window. … … 958 958 959 959 One can eventually choose to feedback instantaneous values by not using any time filter 960 (\np{ln \_bt\_av}\forcode{=.false.}).960 (\np{ln_bt_av}{ln\_bt\_av}\forcode{=.false.}). 961 961 In that case, external mode equations are continuous in time, 962 962 \ie\ they are not re-initialized when starting a new sub-stepping sequence. … … 1135 1135 %------------------------------------------------------------------------------------------------------------- 1136 1136 1137 Options are defined through the \nam{dyn \_ldf} namelist variables.1137 Options are defined through the \nam{dyn_ldf}{dyn\_ldf} namelist variables. 1138 1138 The options available for lateral diffusion are to use either laplacian (rotated or not) or biharmonic operators. 1139 1139 The coefficients may be constant or spatially variable; … … 1162 1162 1163 1163 % ================================================================ 1164 \subsection[Iso-level laplacian (\forcode{ln_dynldf_lap})]{Iso-level laplacian operator (\protect\np{ln \_dynldf\_lap})}1164 \subsection[Iso-level laplacian (\forcode{ln_dynldf_lap})]{Iso-level laplacian operator (\protect\np{ln_dynldf_lap}{ln\_dynldf\_lap})} 1165 1165 \label{subsec:DYN_ldf_lap} 1166 1166 … … 1187 1187 % Rotated laplacian operator 1188 1188 %-------------------------------------------------------------------------------------------------------------- 1189 \subsection[Rotated laplacian (\forcode{ln_dynldf_iso})]{Rotated laplacian operator (\protect\np{ln \_dynldf\_iso})}1189 \subsection[Rotated laplacian (\forcode{ln_dynldf_iso})]{Rotated laplacian operator (\protect\np{ln_dynldf_iso}{ln\_dynldf\_iso})} 1190 1190 \label{subsec:DYN_ldf_iso} 1191 1191 1192 1192 A rotation of the lateral momentum diffusion operator is needed in several cases: 1193 for iso-neutral diffusion in the $z$-coordinate (\np{ln \_dynldf\_iso}\forcode{=.true.}) and1194 for either iso-neutral (\np{ln \_dynldf\_iso}\forcode{=.true.}) or1195 geopotential (\np{ln \_dynldf\_hor}\forcode{=.true.}) diffusion in the $s$-coordinate.1193 for iso-neutral diffusion in the $z$-coordinate (\np{ln_dynldf_iso}{ln\_dynldf\_iso}\forcode{=.true.}) and 1194 for either iso-neutral (\np{ln_dynldf_iso}{ln\_dynldf\_iso}\forcode{=.true.}) or 1195 geopotential (\np{ln_dynldf_hor}{ln\_dynldf\_hor}\forcode{=.true.}) diffusion in the $s$-coordinate. 1196 1196 In the partial step case, coordinates are horizontal except at the deepest level and 1197 no rotation is performed when \np{ln \_dynldf\_hor}\forcode{=.true.}.1197 no rotation is performed when \np{ln_dynldf_hor}{ln\_dynldf\_hor}\forcode{=.true.}. 1198 1198 The diffusion operator is defined simply as the divergence of down gradient momentum fluxes on 1199 1199 each momentum component. … … 1245 1245 % Iso-level bilaplacian operator 1246 1246 %-------------------------------------------------------------------------------------------------------------- 1247 \subsection[Iso-level bilaplacian (\forcode{ln_dynldf_bilap})]{Iso-level bilaplacian operator (\protect\np{ln \_dynldf\_bilap})}1247 \subsection[Iso-level bilaplacian (\forcode{ln_dynldf_bilap})]{Iso-level bilaplacian operator (\protect\np{ln_dynldf_bilap}{ln\_dynldf\_bilap})} 1248 1248 \label{subsec:DYN_ldf_bilap} 1249 1249 … … 1269 1269 Two time stepping schemes can be used for the vertical diffusion term: 1270 1270 $(a)$ a forward time differencing scheme 1271 (\np{ln \_zdfexp}\forcode{=.true.}) using a time splitting technique (\np{nn\_zdfexp} $>$ 1) or1272 $(b)$ a backward (or implicit) time differencing scheme (\np{ln \_zdfexp}\forcode{=.false.})1271 (\np{ln_zdfexp}{ln\_zdfexp}\forcode{=.true.}) using a time splitting technique (\np{nn_zdfexp}{nn\_zdfexp} $>$ 1) or 1272 $(b)$ a backward (or implicit) time differencing scheme (\np{ln_zdfexp}{ln\_zdfexp}\forcode{=.false.}) 1273 1273 (see \autoref{chap:TD}). 1274 Note that namelist variables \np{ln \_zdfexp} and \np{nn\_zdfexp} apply to both tracers and dynamics.1274 Note that namelist variables \np{ln_zdfexp}{ln\_zdfexp} and \np{nn_zdfexp}{nn\_zdfexp} apply to both tracers and dynamics. 1275 1275 1276 1276 The formulation of the vertical subgrid scale physics is the same whatever the vertical coordinate is. … … 1320 1320 three other forcings may enter the dynamical equations by affecting the surface pressure gradient. 1321 1321 1322 (1) When \np{ln \_apr\_dyn}\forcode{=.true.} (see \autoref{sec:SBC_apr}),1322 (1) When \np{ln_apr_dyn}{ln\_apr\_dyn}\forcode{=.true.} (see \autoref{sec:SBC_apr}), 1323 1323 the atmospheric pressure is taken into account when computing the surface pressure gradient. 1324 1324 1325 (2) When \np{ln \_tide\_pot}\forcode{=.true.} and \np{ln\_tide}\forcode{=.true.} (see \autoref{sec:SBC_tide}),1325 (2) When \np{ln_tide_pot}{ln\_tide\_pot}\forcode{=.true.} and \np{ln_tide}{ln\_tide}\forcode{=.true.} (see \autoref{sec:SBC_tide}), 1326 1326 the tidal potential is taken into account when computing the surface pressure gradient. 1327 1327 1328 (3) When \np{nn \_ice\_embd}\forcode{=2} and LIM or CICE is used1328 (3) When \np{nn_ice_embd}{nn\_ice\_embd}\forcode{=2} and LIM or CICE is used 1329 1329 (\ie\ when the sea-ice is embedded in the ocean), 1330 1330 the snow-ice mass is taken into account when computing the surface pressure gradient. … … 1396 1396 1397 1397 The principal idea of the directional limiter is that 1398 water should not be allowed to flow out of a dry tracer cell (i.e. one whose water depth is less than \np{rn \_wdmin1}).1398 water should not be allowed to flow out of a dry tracer cell (i.e. one whose water depth is less than \np{rn_wdmin1}{rn\_wdmin1}). 1399 1399 1400 1400 All the changes associated with this option are made to the barotropic solver for the non-linear … … 1406 1406 1407 1407 The flux across each $u$-face of a tracer cell is multiplied by a factor zuwdmask (an array which depends on ji and jj). 1408 If the user sets \np{ln \_wd\_dl\_ramp}\forcode{=.false.} then zuwdmask is 1 when the1409 flux is from a cell with water depth greater than \np{rn \_wdmin1} and 0 otherwise. If the user sets1410 \np{ln \_wd\_dl\_ramp}\forcode{=.true.} the flux across the face is ramped down as the water depth decreases1411 from 2 * \np{rn \_wdmin1} to \np{rn\_wdmin1}. The use of this ramp reduced grid-scale noise in idealised test cases.1408 If the user sets \np{ln_wd_dl_ramp}{ln\_wd\_dl\_ramp}\forcode{=.false.} then zuwdmask is 1 when the 1409 flux is from a cell with water depth greater than \np{rn_wdmin1}{rn\_wdmin1} and 0 otherwise. If the user sets 1410 \np{ln_wd_dl_ramp}{ln\_wd\_dl\_ramp}\forcode{=.true.} the flux across the face is ramped down as the water depth decreases 1411 from 2 * \np{rn_wdmin1}{rn\_wdmin1} to \np{rn\_wdmin1}. The use of this ramp reduced grid-scale noise in idealised test cases. 1412 1412 1413 1413 At the point where the flux across a $u$-face is multiplied by zuwdmask , we have chosen … … 1425 1425 fields (tracers independent of $x$, $y$ and $z$). Our scheme conserves constant tracers because 1426 1426 the velocities used at the tracer cell faces on the baroclinic timesteps are carefully calculated by dynspg\_ts 1427 to equal their mean value during the barotropic steps. If the user sets \np{ln \_wd\_dl\_bc}\forcode{=.true.}, the1427 to equal their mean value during the barotropic steps. If the user sets \np{ln_wd_dl_bc}{ln\_wd\_dl\_bc}\forcode{=.true.}, the 1428 1428 baroclinic velocities are also multiplied by a suitably weighted average of zuwdmask. 1429 1429 … … 1658 1658 1659 1659 $\bullet$ vector invariant form or linear free surface 1660 (\np{ln \_dynhpg\_vec}\forcode{=.true.} ; \texttt{vvl?} not defined):1660 (\np{ln_dynhpg_vec}{ln\_dynhpg\_vec}\forcode{=.true.} ; \texttt{vvl?} not defined): 1661 1661 \[ 1662 1662 % \label{eq:DYN_nxt_vec} … … 1670 1670 1671 1671 $\bullet$ flux form and nonlinear free surface 1672 (\np{ln \_dynhpg\_vec}\forcode{=.false.} ; \texttt{vvl?} defined):1672 (\np{ln_dynhpg_vec}{ln\_dynhpg\_vec}\forcode{=.false.} ; \texttt{vvl?} defined): 1673 1673 \[ 1674 1674 % \label{eq:DYN_nxt_flux} … … 1683 1683 where RHS is the right hand side of the momentum equation, 1684 1684 the subscript $f$ denotes filtered values and $\gamma$ is the Asselin coefficient. 1685 $\gamma$ is initialized as \np{nn \_atfp} (namelist parameter).1686 Its default value is \np{nn \_atfp}\forcode{=10.e-3}.1685 $\gamma$ is initialized as \np{nn_atfp}{nn\_atfp} (namelist parameter). 1686 Its default value is \np{nn_atfp}{nn\_atfp}\forcode{=10.e-3}. 1687 1687 In both cases, the modified Asselin filter is not applied since perfect conservation is not an issue for 1688 1688 the momentum equations.
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