/[MITgcm]/manual/s_phys_pkgs/text/gmredi.tex
ViewVC logotype

Diff of /manual/s_phys_pkgs/text/gmredi.tex

Parent Directory Parent Directory | Revision Log Revision Log | View Revision Graph Revision Graph | View Patch Patch

revision 1.4 by adcroft, Tue Nov 13 14:54:50 2001 UTC revision 1.15 by jmc, Mon Aug 30 23:09:21 2010 UTC
# Line 1  Line 1 
1  \section{Gent/McWiliams/Redi SGS Eddy parameterization}  \subsection{GMREDI: Gent/McWiliams/Redi SGS Eddy Parameterization}
2    \label{sec:pkg:gmredi}
3    \begin{rawhtml}
4    <!-- CMIREDIR:gmredi: -->
5    \end{rawhtml}
6    
7  There are two parts to the Redi/GM parameterization of geostrophic  There are two parts to the Redi/GM parameterization of geostrophic
8  eddies. The first aims to mix tracer properties along isentropes  eddies. The first aims to mix tracer properties along isentropes
# Line 31  and Redi scheme, substantial cancellatio Line 35  and Redi scheme, substantial cancellatio
35  that the horizontal fluxes are unmodified from the lateral diffusion  that the horizontal fluxes are unmodified from the lateral diffusion
36  parameterization.  parameterization.
37    
38  \subsection{Redi scheme: Isopycnal diffusion}  \subsubsection{Redi scheme: Isopycnal diffusion}
39    
40  The Redi scheme diffuses tracers along isopycnals and introduces a  The Redi scheme diffuses tracers along isopycnals and introduces a
41  term in the tendency (rhs) of such a tracer (here $\tau$) of the form:  term in the tendency (rhs) of such a tracer (here $\tau$) of the form:
# Line 71  S_x & S_y & |S|^2 \\ Line 75  S_x & S_y & |S|^2 \\
75  \end{equation}  \end{equation}
76    
77    
78  \subsection{GM parameterization}  \subsubsection{GM parameterization}
79    
80  The GM parameterization aims to parameterise the ``advective'' or  The GM parameterization aims to parameterise the ``advective'' or
81  ``transport'' effect of geostrophic eddies by means of a ``bolus''  ``transport'' effect of geostrophic eddies by means of a ``bolus''
# Line 100  F_y & = & \kappa_{GM} S_y Line 104  F_y & = & \kappa_{GM} S_y
104  This is the form of the GM parameterization as applied by Donabasaglu,  This is the form of the GM parameterization as applied by Donabasaglu,
105  1997, in MOM versions 1 and 2.  1997, in MOM versions 1 and 2.
106    
107  \subsection{Griffies Skew Flux}  \subsubsection{Griffies Skew Flux}
108    
109  Griffies notes that the discretisation of bolus velocities involves  Griffies notes that the discretisation of bolus velocities involves
110  multiple layers of differencing and interpolation that potentially  multiple layers of differencing and interpolation that potentially
# Line 187  $S_y$: {\bf SlopeY} (argument on exit) Line 191  $S_y$: {\bf SlopeY} (argument on exit)
191    
192    
193    
194  \subsection{Variable $\kappa_{GM}$}  \subsubsection{Variable $\kappa_{GM}$}
195    
196  Visbeck et al., 1996, suggest making the eddy coefficient,  Visbeck et al., 1996, suggest making the eddy coefficient,
197  $\kappa_{GM}$, a function of the Eady growth rate,  $\kappa_{GM}$, a function of the Eady growth rate,
# Line 213  Substituting into the formula for $\kapp Line 217  Substituting into the formula for $\kapp
217  \end{displaymath}  \end{displaymath}
218    
219    
220  \subsection{Tapering and stability}  \subsubsection{Tapering and stability}
221    
222  Experience with the GFDL model showed that the GM scheme has to be  Experience with the GFDL model showed that the GM scheme has to be
223  matched to the convective parameterization. This was originally  matched to the convective parameterization. This was originally
# Line 238  $z_\sigma^{*}$: {\bf dRdSigmaLtd} (argum Line 242  $z_\sigma^{*}$: {\bf dRdSigmaLtd} (argum
242    
243  \begin{figure}  \begin{figure}
244  \begin{center}  \begin{center}
245  \resizebox{5.0in}{3.0in}{\includegraphics{part6/tapers.eps}}  \resizebox{5.0in}{3.0in}{\includegraphics{s_phys_pkgs/figs/tapers.eps}}
246  \end{center}  \end{center}
247  \caption{Taper functions used in GKW91 and DM95.}  \caption{Taper functions used in GKW99 and DM95.}
248  \label{fig:tapers}  \label{fig:tapers}
249  \end{figure}  \end{figure}
250    
251  \begin{figure}  \begin{figure}
252  \begin{center}  \begin{center}
253  \resizebox{5.0in}{3.0in}{\includegraphics{part6/effective_slopes.eps}}  \resizebox{5.0in}{3.0in}{\includegraphics{s_phys_pkgs/figs/effective_slopes.eps}}
254  \end{center}  \end{center}
255  \caption{Effective slope as a function of ``true'' slope using Cox  \caption{Effective slope as a function of ``true'' slope using Cox
256  slope clipping, GKW91 limiting and DM95 limiting.}  slope clipping, GKW91 limiting and DM95 limiting.}
# Line 254  slope clipping, GKW91 limiting and DM95 Line 258  slope clipping, GKW91 limiting and DM95
258  \end{figure}  \end{figure}
259    
260    
261  \subsubsection{Slope clipping}  Slope clipping:
262    
263  Deep convection sites and the mixed layer are indicated by  Deep convection sites and the mixed layer are indicated by
264  homogenized, unstable or nearly unstable stratification. The slopes in  homogenized, unstable or nearly unstable stratification. The slopes in
# Line 301  parameterization. Limiting the slopes al Line 305  parameterization. Limiting the slopes al
305  of the GM/Redi parameterization, re-introducing diabatic fluxes in  of the GM/Redi parameterization, re-introducing diabatic fluxes in
306  regions where the limiting is in effect.  regions where the limiting is in effect.
307    
308  \subsubsection{Tapering: Gerdes, Koberle and Willebrand, Clim. Dyn. 1991}  Tapering: Gerdes, Koberle and Willebrand, Clim. Dyn. 1991:
309    
310  The tapering scheme used in Gerdes et al., 1991, (\cite{gkw91})  The tapering scheme used in Gerdes et al., 1999, (\cite{gkw:99})
311  addressed two issues with the clipping method: the introduction of  addressed two issues with the clipping method: the introduction of
312  large vertical fluxes in addition to convective adjustment fluxes is  large vertical fluxes in addition to convective adjustment fluxes is
313  avoided by tapering the GM/Redi slopes back to zero in  avoided by tapering the GM/Redi slopes back to zero in
# Line 325  that the effective vertical diffusivity Line 329  that the effective vertical diffusivity
329  The GKW tapering scheme is activated in the model by setting {\bf  The GKW tapering scheme is activated in the model by setting {\bf
330  GM\_tap\-er\_scheme = 'gkw91'} in {\em data.gmredi}.  GM\_tap\-er\_scheme = 'gkw91'} in {\em data.gmredi}.
331    
332  \subsection{Tapering: Danabasoglu and McWilliams, J. Clim. 1995}  \subsubsection{Tapering: Danabasoglu and McWilliams, J. Clim. 1995}
333    
334  The tapering scheme used by Danabasoglu and McWilliams, 1995,  The tapering scheme used by Danabasoglu and McWilliams, 1995,
335  \cite{DM95}, followed a similar procedure but used a different  \cite{dm:95}, followed a similar procedure but used a different
336  tapering function, $f_1(S)$:  tapering function, $f_1(S)$:
337  \begin{equation}  \begin{equation}
338  f_1(S) = \frac{1}{2} \left( 1+\tanh \left[ \frac{S_c - |S|}{S_d} \right] \right)  f_1(S) = \frac{1}{2} \left( 1+\tanh \left[ \frac{S_c - |S|}{S_d} \right] \right)
# Line 342  slopes. Line 346  slopes.
346  The DM tapering scheme is activated in the model by setting {\bf  The DM tapering scheme is activated in the model by setting {\bf
347  GM\_tap\-er\_scheme = 'dm95'} in {\em data.gmredi}.  GM\_tap\-er\_scheme = 'dm95'} in {\em data.gmredi}.
348    
349  \subsection{Tapering: Large, Danabasoglu and Doney, JPO 1997}  \subsubsection{Tapering: Large, Danabasoglu and Doney, JPO 1997}
350    
351  The tapering used in Large et al., 1997, \cite{ldd97}, is based on the  The tapering used in Large et al., 1997, \cite{ldd:97}, is based on the
352  DM95 tapering scheme, but also tapers the scheme with an additional  DM95 tapering scheme, but also tapers the scheme with an additional
353  function of height, $f_2(z)$, so that the GM/Redi SGS fluxes are  function of height, $f_2(z)$, so that the GM/Redi SGS fluxes are
354  reduced near the surface:  reduced near the surface:
# Line 372  clipping and for comparison b) using hor Line 376  clipping and for comparison b) using hor
376  \label{fig-mixedlayer}  \label{fig-mixedlayer}
377  \end{figure}  \end{figure}
378    
379    \subsubsection{Package Reference}
380    \label{sec:pkg:gmredi:diagnostics}
381    
382    {\footnotesize
383    \begin{verbatim}
384    ------------------------------------------------------------------------
385    <-Name->|Levs|<-parsing code->|<--  Units   -->|<- Tile (max=80c)
386    ------------------------------------------------------------------------
387    GM_VisbK|  1 |SM P    M1      |m^2/s           |Mixing coefficient from Visbeck etal parameterization
388    GM_Kux  | 15 |UU P 177MR      |m^2/s           |K_11 element (U.point, X.dir) of GM-Redi tensor
389    GM_Kvy  | 15 |VV P 176MR      |m^2/s           |K_22 element (V.point, Y.dir) of GM-Redi tensor
390    GM_Kuz  | 15 |UU   179MR      |m^2/s           |K_13 element (U.point, Z.dir) of GM-Redi tensor
391    GM_Kvz  | 15 |VV   178MR      |m^2/s           |K_23 element (V.point, Z.dir) of GM-Redi tensor
392    GM_Kwx  | 15 |UM   181LR      |m^2/s           |K_31 element (W.point, X.dir) of GM-Redi tensor
393    GM_Kwy  | 15 |VM   180LR      |m^2/s           |K_32 element (W.point, Y.dir) of GM-Redi tensor
394    GM_Kwz  | 15 |WM P    LR      |m^2/s           |K_33 element (W.point, Z.dir) of GM-Redi tensor
395    GM_PsiX | 15 |UU   184LR      |m^2/s           |GM Bolus transport stream-function : X component
396    GM_PsiY | 15 |VV   183LR      |m^2/s           |GM Bolus transport stream-function : Y component
397    GM_KuzTz| 15 |UU   186MR      |degC.m^3/s      |Redi Off-diagonal Tempetature flux: X component
398    GM_KvzTz| 15 |VV   185MR      |degC.m^3/s      |Redi Off-diagonal Tempetature flux: Y component
399    \end{verbatim}
400    }
401    
402    \subsubsection{Experiments and tutorials that use gmredi}
403    \label{sec:pkg:gmredi:experiments}
404    
405    \begin{itemize}
406    \item{Global Ocean tutorial, in tutorial\_global\_oce\_latlon verification directory,
407    described in section \ref{sec:eg-global} }
408    \item{ Front Relax experiment, in front\_relax verification directory.}
409    \item{ Ideal 2D Ocean experiment, in ideal\_2D\_oce verification directory.}
410    \end{itemize}
411    
412    % DO NOT EDIT HERE
413    
414    
415    

Legend:
Removed from v.1.4  
changed lines
  Added in v.1.15

  ViewVC Help
Powered by ViewVC 1.1.22