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1  % $Header$  % $Header$
2  % $Name$  % $Name$
3    
4    %\section{Getting started}
5    
6  \begin{center}  In this section, we describe how to use the model. In the first
7  {\Large \textbf{Using the model}}  section, we provide enough information to help you get started with
8    the model. We believe the best way to familiarize yourself with the
9    model is to run the case study examples provided with the base
10    version. Information on how to obtain, compile, and run the code is
11    found there as well as a brief description of the model structure
12    directory and the case study examples.  The latter and the code
13    structure are described more fully in chapters
14    \ref{chap:discretization} and \ref{chap:sarch}, respectively. Here, in
15    this section, we provide information on how to customize the code when
16    you are ready to try implementing the configuration you have in mind.
17    
18  \vspace*{4mm}  \section{Where to find information}
19    \label{sect:whereToFindInfo}
20    
21  \vspace*{3mm} {\large July 2001}  A web site is maintained for release 2 (``Pelican'') of MITgcm:
22  \end{center}  \begin{rawhtml} <A href=http://mitgcm.org/pelican/ target="idontexist"> \end{rawhtml}
23    \begin{verbatim}
24    http://mitgcm.org/pelican
25    \end{verbatim}
26    \begin{rawhtml} </A> \end{rawhtml}
27    Here you will find an on-line version of this document, a
28    ``browsable'' copy of the code and a searchable database of the model
29    and site, as well as links for downloading the model and
30    documentation, to data-sources, and other related sites.
31    
32    There is also a web-archived support mailing list for the model that
33    you can email at \texttt{MITgcm-support@mitgcm.org} or browse at:
34    \begin{rawhtml} <A href=http://mitgcm.org/mailman/listinfo/mitgcm-support/ target="idontexist"> \end{rawhtml}
35    \begin{verbatim}
36    http://mitgcm.org/mailman/listinfo/mitgcm-support/
37    http://mitgcm.org/pipermail/mitgcm-support/
38    \end{verbatim}
39    \begin{rawhtml} </A> \end{rawhtml}
40    Essentially all of the MITgcm web pages can be searched using a
41    popular web crawler such as Google or through our own search facility:
42    \begin{rawhtml} <A href=http://mitgcm.org/mailman/htdig/ target="idontexist"> \end{rawhtml}
43    \begin{verbatim}
44    http://mitgcm.org/htdig/
45    \end{verbatim}
46    \begin{rawhtml} </A> \end{rawhtml}
47    %%% http://www.google.com/search?q=hydrostatic+site%3Amitgcm.org
48    
 In this part, we describe how to use the model. In the first section, we  
 provide enough information to help you get started with the model. We  
 believe the best way to familiarize yourself with the model is to run the  
 case study examples provided with the base version. Information on how to  
 obtain, compile, and run the code is found there as well as a brief  
 description of the model structure directory and the case study examples.  
 The latter and the code structure are described more fully in sections 2 and  
 3, respectively. In section 4, we provide information on how to customize  
 the code when you are ready to try implementing the configuration you have  
 in mind.  
49    
 \section{Getting started}  
50    
51  \subsection{Obtaining the code}  \section{Obtaining the code}
52    \label{sect:obtainingCode}
53    
54  The reference web site for the model is:  MITgcm can be downloaded from our system by following
55  \begin{verbatim}  the instructions below. As a courtesy we ask that you send e-mail to us at
56  http://mitgcm.org  \begin{rawhtml} <A href=mailto:MITgcm-support@mitgcm.org> \end{rawhtml}
57  \end{verbatim}  MITgcm-support@mitgcm.org
58    \begin{rawhtml} </A> \end{rawhtml}
59    to enable us to keep track of who's using the model and in what application.
60    You can download the model two ways:
61    
62    \begin{enumerate}
63    \item Using CVS software. CVS is a freely available source code management
64    tool. To use CVS you need to have the software installed. Many systems
65    come with CVS pre-installed, otherwise good places to look for
66    the software for a particular platform are
67    \begin{rawhtml} <A href=http://www.cvshome.org/ target="idontexist"> \end{rawhtml}
68    cvshome.org
69    \begin{rawhtml} </A> \end{rawhtml}
70    and
71    \begin{rawhtml} <A href=http://www.wincvs.org/ target="idontexist"> \end{rawhtml}
72    wincvs.org
73    \begin{rawhtml} </A> \end{rawhtml}
74    .
75    
76    \item Using a tar file. This method is simple and does not
77    require any special software. However, this method does not
78    provide easy support for maintenance updates.
79    
80  On this site, you can download the model as well as find useful information,  \end{enumerate}
81  some of which might overlap with what is written here. There is also a  
82  support news group for the model located at (send your message to \texttt{%  \subsubsection{Checkout from CVS}
83  support@mitgcm.org}):  \label{sect:cvs_checkout}
 \begin{verbatim}  
 news://mitgcm.org/mitgcm.support  
 \end{verbatim}  
84    
85  If CVS is available on your system, we strongly encourage you to use it. CVS  If CVS is available on your system, we strongly encourage you to use it. CVS
86  provides an efficient and elegant way of organizing your code and keeping  provides an efficient and elegant way of organizing your code and keeping
87  track of your changes. If CVS is not available on your machine, you can also  track of your changes. If CVS is not available on your machine, you can also
88  download a tar file.  download a tar file.
89    
90  \subsubsection{using CVS}  Before you can use CVS, the following environment variable(s) should
91    be set within your shell.  For a csh or tcsh shell, put the following
92    \begin{verbatim}
93    % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/gcmpack
94    \end{verbatim}
95    in your .cshrc or .tcshrc file.  For bash or sh shells, put:
96    \begin{verbatim}
97    % export CVSROOT=':pserver:cvsanon@mitgcm.org:/u/gcmpack'
98    \end{verbatim}
99    in your \texttt{.profile} or \texttt{.bashrc} file.
100    
101    
102  Before you can use CVS, the following environment variable has to be set in  To get MITgcm through CVS, first register with the MITgcm CVS server
103  your .cshrc or .tcshrc:  using command:
104  \begin{verbatim}  \begin{verbatim}
 % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/u0/gcmpack  
105  % cvs login ( CVS password: cvsanon )  % cvs login ( CVS password: cvsanon )
106  \end{verbatim}  \end{verbatim}
107    You only need to do a ``cvs login'' once.
108    
109  You only need to do ``cvs login'' once. To obtain the latest source:  To obtain the latest sources type:
110  \begin{verbatim}  \begin{verbatim}
111  % cvs co -d directory models/MITgcmUV  % cvs co MITgcm
112  \end{verbatim}  \end{verbatim}
113    or to get a specific release type:
114    \begin{verbatim}
115    % cvs co -P -r checkpoint52i_post  MITgcm
116    \end{verbatim}
117    The MITgcm web site contains further directions concerning the source
118    code and CVS.  It also contains a web interface to our CVS archive so
119    that one may easily view the state of files, revisions, and other
120    development milestones:
121    \begin{rawhtml} <A href=''http://mitgcm.org/download'' target="idontexist"> \end{rawhtml}
122    \begin{verbatim}
123    http://mitgcm.org/source_code.html
124    \end{verbatim}
125    \begin{rawhtml} </A> \end{rawhtml}
126    
127  This creates a directory called \textit{directory}. If \textit{directory}  As a convenience, the MITgcm CVS server contains aliases which are
128  exists this command updates your code based on the repository. Each  named subsets of the codebase.  These aliases can be especially
129  directory in the source tree contains a directory \textit{CVS}. This  helpful when used over slow internet connections or on machines with
130  information is required by CVS to keep track of your file versions with  restricted storage space.  Table \ref{tab:cvsModules} contains a list
131  respect to the repository. Don't edit the files in \textit{CVS}! To obtain a  of CVS aliases
132  specific \textit{version} that is not the latest source:  \begin{table}[htb]
133      \centering
134      \begin{tabular}[htb]{|lp{3.25in}|}\hline
135        \textbf{Alias Name}    &  \textbf{Information (directories) Contained}  \\\hline
136        \texttt{MITgcm\_code}  &  Only the source code -- none of the verification examples.  \\
137        \texttt{MITgcm\_verif\_basic}
138        &  Source code plus a small set of the verification examples
139        (\texttt{global\_ocean.90x40x15}, \texttt{aim.5l\_cs}, \texttt{hs94.128x64x5},
140        \texttt{front\_relax}, and \texttt{plume\_on\_slope}).  \\
141        \texttt{MITgcm\_verif\_atmos}  &  Source code plus all of the atmospheric examples.  \\
142        \texttt{MITgcm\_verif\_ocean}  &  Source code plus all of the oceanic examples.  \\
143        \texttt{MITgcm\_verif\_all}    &  Source code plus all of the
144        verification examples. \\\hline
145      \end{tabular}
146      \caption{MITgcm CVS Modules}
147      \label{tab:cvsModules}
148    \end{table}
149    
150    The checkout process creates a directory called \textit{MITgcm}. If
151    the directory \textit{MITgcm} exists this command updates your code
152    based on the repository. Each directory in the source tree contains a
153    directory \textit{CVS}. This information is required by CVS to keep
154    track of your file versions with respect to the repository. Don't edit
155    the files in \textit{CVS}!  You can also use CVS to download code
156    updates.  More extensive information on using CVS for maintaining
157    MITgcm code can be found
158    \begin{rawhtml} <A href=''http://mitgcm.org/usingcvstoget.html'' target="idontexist"> \end{rawhtml}
159    here
160    \begin{rawhtml} </A> \end{rawhtml}
161    .
162    It is important to note that the CVS aliases in Table
163    \ref{tab:cvsModules} cannot be used in conjunction with the CVS
164    \texttt{-d DIRNAME} option.  However, the \texttt{MITgcm} directories
165    they create can be changed to a different name following the check-out:
166  \begin{verbatim}  \begin{verbatim}
167  % cvs co -d directory -r version models/MITgcmUV     %  cvs co MITgcm_verif_basic
168       %  mv MITgcm MITgcm_verif_basic
169  \end{verbatim}  \end{verbatim}
170    
 \subsubsection{other methods}  
171    
172  You can download the model as a tar file from the reference web site at:  \subsubsection{Conventional download method}
173    \label{sect:conventionalDownload}
174    
175    If you do not have CVS on your system, you can download the model as a
176    tar file from the web site at:
177    \begin{rawhtml} <A href=http://mitgcm.org/download target="idontexist"> \end{rawhtml}
178  \begin{verbatim}  \begin{verbatim}
179  http://mitgcm.org/download/  http://mitgcm.org/download/
180  \end{verbatim}  \end{verbatim}
181    \begin{rawhtml} </A> \end{rawhtml}
182  \subsection{Model and directory structure}  The tar file still contains CVS information which we urge you not to
183    delete; even if you do not use CVS yourself the information can help
184  The ``numerical'' model is contained within a execution environment support  us if you should need to send us your copy of the code.  If a recent
185  wrapper. This wrapper is designed to provide a general framework for  tar file does not exist, then please contact the developers through
186  grid-point models. MITgcmUV is a specific numerical model that uses the  the
187  framework. Under this structure the model is split into execution  \begin{rawhtml} <A href=''mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
188  environment support code and conventional numerical model code. The  MITgcm-support@mitgcm.org
189  execution environment support code is held under the \textit{eesupp}  \begin{rawhtml} </A> \end{rawhtml}
190  directory. The grid point model code is held under the \textit{model}  mailing list.
191  directory. Code execution actually starts in the \textit{eesupp} routines  
192  and not in the \textit{model} routines. For this reason the top-level  \subsubsection{Upgrading from an earlier version}
193  \textit{MAIN.F} is in the \textit{eesupp/src} directory. In general,  
194  end-users should not need to worry about this level. The top-level routine  If you already have an earlier version of the code you can ``upgrade''
195  for the numerical part of the code is in \textit{model/src/THE\_MODEL\_MAIN.F%  your copy instead of downloading the entire repository again. First,
196  }. Here is a brief description of the directory structure of the model under  ``cd'' (change directory) to the top of your working copy:
197  the root tree (a detailed description is given in section 3: Code structure).  \begin{verbatim}
198    % cd MITgcm
199    \end{verbatim}
200    and then issue the cvs update command such as:
201    \begin{verbatim}
202    % cvs -q update -r checkpoint52i_post -d -P
203    \end{verbatim}
204    This will update the ``tag'' to ``checkpoint52i\_post'', add any new
205    directories (-d) and remove any empty directories (-P). The -q option
206    means be quiet which will reduce the number of messages you'll see in
207    the terminal. If you have modified the code prior to upgrading, CVS
208    will try to merge your changes with the upgrades. If there is a
209    conflict between your modifications and the upgrade, it will report
210    that file with a ``C'' in front, e.g.:
211    \begin{verbatim}
212    C model/src/ini_parms.F
213    \end{verbatim}
214    If the list of conflicts scrolled off the screen, you can re-issue the
215    cvs update command and it will report the conflicts. Conflicts are
216    indicated in the code by the delimites ``$<<<<<<<$'', ``======='' and
217    ``$>>>>>>>$''. For example,
218    {\small
219    \begin{verbatim}
220    <<<<<<< ini_parms.F
221         & bottomDragLinear,myOwnBottomDragCoefficient,
222    =======
223         & bottomDragLinear,bottomDragQuadratic,
224    >>>>>>> 1.18
225    \end{verbatim}
226    }
227    means that you added ``myOwnBottomDragCoefficient'' to a namelist at
228    the same time and place that we added ``bottomDragQuadratic''. You
229    need to resolve this conflict and in this case the line should be
230    changed to:
231    {\small
232    \begin{verbatim}
233         & bottomDragLinear,bottomDragQuadratic,myOwnBottomDragCoefficient,
234    \end{verbatim}
235    }
236    and the lines with the delimiters ($<<<<<<$,======,$>>>>>>$) be deleted.
237    Unless you are making modifications which exactly parallel
238    developments we make, these types of conflicts should be rare.
239    
240    \paragraph*{Upgrading to the current pre-release version}
241    
242    We don't make a ``release'' for every little patch and bug fix in
243    order to keep the frequency of upgrades to a minimum. However, if you
244    have run into a problem for which ``we have already fixed in the
245    latest code'' and we haven't made a ``tag'' or ``release'' since that
246    patch then you'll need to get the latest code:
247    \begin{verbatim}
248    % cvs -q update -A -d -P
249    \end{verbatim}
250    Unlike, the ``check-out'' and ``update'' procedures above, there is no
251    ``tag'' or release name. The -A tells CVS to upgrade to the
252    very latest version. As a rule, we don't recommend this since you
253    might upgrade while we are in the processes of checking in the code so
254    that you may only have part of a patch. Using this method of updating
255    also means we can't tell what version of the code you are working
256    with. So please be sure you understand what you're doing.
257    
258    \section{Model and directory structure}
259    
260    The ``numerical'' model is contained within a execution environment
261    support wrapper. This wrapper is designed to provide a general
262    framework for grid-point models. MITgcmUV is a specific numerical
263    model that uses the framework. Under this structure the model is split
264    into execution environment support code and conventional numerical
265    model code. The execution environment support code is held under the
266    \textit{eesupp} directory. The grid point model code is held under the
267    \textit{model} directory. Code execution actually starts in the
268    \textit{eesupp} routines and not in the \textit{model} routines. For
269    this reason the top-level \textit{MAIN.F} is in the
270    \textit{eesupp/src} directory. In general, end-users should not need
271    to worry about this level. The top-level routine for the numerical
272    part of the code is in \textit{model/src/THE\_MODEL\_MAIN.F}. Here is
273    a brief description of the directory structure of the model under the
274    root tree (a detailed description is given in section 3: Code
275    structure).
276    
277  \begin{itemize}  \begin{itemize}
 \item \textit{bin}: this directory is initially empty. It is the default  
 directory in which to compile the code.  
278    
279    \item \textit{bin}: this directory is initially empty. It is the
280      default directory in which to compile the code.
281      
282  \item \textit{diags}: contains the code relative to time-averaged  \item \textit{diags}: contains the code relative to time-averaged
283  diagnostics. It is subdivided into two subdirectories \textit{inc} and    diagnostics. It is subdivided into two subdirectories \textit{inc}
284  \textit{src} that contain include files (*.\textit{h} files) and fortran    and \textit{src} that contain include files (*.\textit{h} files) and
285  subroutines (*.\textit{F} files), respectively.    Fortran subroutines (*.\textit{F} files), respectively.
286    
287  \item \textit{doc}: contains brief documentation notes.  \item \textit{doc}: contains brief documentation notes.
288      
289  \item \textit{eesupp}: contains the execution environment source code. Also  \item \textit{eesupp}: contains the execution environment source code.
290  subdivided into two subdirectories \textit{inc} and \textit{src}.    Also subdivided into two subdirectories \textit{inc} and
291      \textit{src}.
292  \item \textit{exe}: this directory is initially empty. It is the default    
293  directory in which to execute the code.  \item \textit{exe}: this directory is initially empty. It is the
294      default directory in which to execute the code.
295  \item \textit{model}: this directory contains the main source code. Also    
296  subdivided into two subdirectories \textit{inc} and \textit{src}.  \item \textit{model}: this directory contains the main source code.
297      Also subdivided into two subdirectories \textit{inc} and
298  \item \textit{pkg}: contains the source code for the packages. Each package    \textit{src}.
299  corresponds to a subdirectory. For example, \textit{gmredi} contains the    
300  code related to the Gent-McWilliams/Redi scheme, \textit{aim} the code  \item \textit{pkg}: contains the source code for the packages. Each
301  relative to the atmospheric intermediate physics. The packages are described    package corresponds to a subdirectory. For example, \textit{gmredi}
302  in detail in section 3.    contains the code related to the Gent-McWilliams/Redi scheme,
303      \textit{aim} the code relative to the atmospheric intermediate
304  \item \textit{tools}: this directory contains various useful tools. For    physics. The packages are described in detail in section 3.
305  example, \textit{genmake} is a script written in csh (C-shell) that should    
306  be used to generate your makefile. The directory \textit{adjoint} contains  \item \textit{tools}: this directory contains various useful tools.
307  the makefile specific to the Tangent linear and Adjoint Compiler (TAMC) that    For example, \textit{genmake2} is a script written in csh (C-shell)
308  generates the adjoint code. The latter is described in details in part V.    that should be used to generate your makefile. The directory
309      \textit{adjoint} contains the makefile specific to the Tangent
310      linear and Adjoint Compiler (TAMC) that generates the adjoint code.
311      The latter is described in details in part V.
312      
313  \item \textit{utils}: this directory contains various utilities. The  \item \textit{utils}: this directory contains various utilities. The
314  subdirectory \textit{knudsen2} contains code and a makefile that compute    subdirectory \textit{knudsen2} contains code and a makefile that
315  coefficients of the polynomial approximation to the knudsen formula for an    compute coefficients of the polynomial approximation to the knudsen
316  ocean nonlinear equation of state. The \textit{matlab} subdirectory contains    formula for an ocean nonlinear equation of state. The
317  matlab scripts for reading model output directly into matlab. \textit{scripts%    \textit{matlab} subdirectory contains matlab scripts for reading
318  } contains C-shell post-processing scripts for joining processor-based and    model output directly into matlab. \textit{scripts} contains C-shell
319  tiled-based model output.    post-processing scripts for joining processor-based and tiled-based
320      model output.
321      
322    \item \textit{verification}: this directory contains the model
323      examples. See section \ref{sect:modelExamples}.
324    
 \item \textit{verification}: this directory contains the model examples. See  
 below.  
325  \end{itemize}  \end{itemize}
326    
327  \subsection{Model examples}  \section{Example experiments}
328    \label{sect:modelExamples}
329  Now that you have successfully downloaded the model code we recommend that  
330  you first try to run the examples provided with the base version. You will  %% a set of twenty-four pre-configured numerical experiments
331  probably want to run the example that is the closest to the configuration  
332  you will use eventually. The examples are located in subdirectories under  The MITgcm distribution comes with more than a dozen pre-configured
333  the directory \textit{verification} and are briefly described below (a full  numerical experiments. Some of these example experiments are tests of
334  description is given in section 2):  individual parts of the model code, but many are fully fledged
335    numerical simulations. A few of the examples are used for tutorial
336    documentation in sections \ref{sect:eg-baro} - \ref{sect:eg-global}.
337    The other examples follow the same general structure as the tutorial
338    examples. However, they only include brief instructions in a text file
339    called {\it README}.  The examples are located in subdirectories under
340    the directory \textit{verification}. Each example is briefly described
341    below.
342    
343  \subsubsection{List of model examples}  \subsection{Full list of model examples}
344    
345  \begin{itemize}  \begin{enumerate}
346      
347  \item \textit{exp0} - single layer, ocean double gyre (barotropic with  \item \textit{exp0} - single layer, ocean double gyre (barotropic with
348  free-surface).    free-surface). This experiment is described in detail in section
349      \ref{sect:eg-baro}.
 \item \textit{exp1} - 4 layers, ocean double gyre.  
350    
351    \item \textit{exp1} - Four layer, ocean double gyre. This experiment
352      is described in detail in section \ref{sect:eg-baroc}.
353      
354  \item \textit{exp2} - 4x4 degree global ocean simulation with steady  \item \textit{exp2} - 4x4 degree global ocean simulation with steady
355  climatological forcing.    climatological forcing. This experiment is described in detail in
356      section \ref{sect:eg-global}.
357  \item \textit{exp4} - flow over a Gaussian bump in open-water or channel    
358  with open boundaries.  \item \textit{exp4} - Flow over a Gaussian bump in open-water or
359      channel with open boundaries.
360      
361    \item \textit{exp5} - Inhomogenously forced ocean convection in a
362      doubly periodic box.
363    
364  \item \textit{exp5} - inhomogenously forced ocean convection in a doubly  \item \textit{front\_relax} - Relaxation of an ocean thermal front (test for
 periodic box.  
   
 \item \textit{front\_relax} - relaxation of an ocean thermal front (test for  
365  Gent/McWilliams scheme). 2D (Y-Z).  Gent/McWilliams scheme). 2D (Y-Z).
366    
367  \item \textit{internal wave} - ocean internal wave forced by open boundary  \item \textit{internal wave} - Ocean internal wave forced by open
368  conditions.    boundary conditions.
369      
370  \item \textit{natl\_box} - eastern subtropical North Atlantic with KPP  \item \textit{natl\_box} - Eastern subtropical North Atlantic with KPP
371  scheme; 1 month integration    scheme; 1 month integration
372      
373  \item \textit{hs94.1x64x5} - zonal averaged atmosphere using Held and Suarez  \item \textit{hs94.1x64x5} - Zonal averaged atmosphere using Held and
374  '94 forcing.    Suarez '94 forcing.
375      
376  \item \textit{hs94.128x64x5} - 3D atmosphere dynamics using Held and Suarez  \item \textit{hs94.128x64x5} - 3D atmosphere dynamics using Held and
377  '94 forcing.    Suarez '94 forcing.
378      
379  \item \textit{hs94.cs-32x32x5} - 3D atmosphere dynamics using Held and  \item \textit{hs94.cs-32x32x5} - 3D atmosphere dynamics using Held and
380  Suarez '94 forcing on the cubed sphere.    Suarez '94 forcing on the cubed sphere.
381      
382  \item \textit{aim.5l\_zon-ave} - Intermediate Atmospheric physics, 5 layers  \item \textit{aim.5l\_zon-ave} - Intermediate Atmospheric physics.
383  Molteni physics package. Global Zonal Mean configuration, 1x64x5 resolution.    Global Zonal Mean configuration, 1x64x5 resolution.
384      
385  \item \textit{aim.5l\_XZ\_Equatorial\_Slice} - Intermediate Atmospheric  \item \textit{aim.5l\_XZ\_Equatorial\_Slice} - Intermediate
386  physics, 5 layers Molteni physics package. Equatorial Slice configuration.    Atmospheric physics, equatorial Slice configuration.  2D (X-Z).
387  2D (X-Z).    
   
388  \item \textit{aim.5l\_Equatorial\_Channel} - Intermediate Atmospheric  \item \textit{aim.5l\_Equatorial\_Channel} - Intermediate Atmospheric
389  physics, 5 layers Molteni physics package. 3D Equatorial Channel    physics. 3D Equatorial Channel configuration.
390  configuration (not completely tested).    
391    \item \textit{aim.5l\_LatLon} - Intermediate Atmospheric physics.
392  \item \textit{aim.5l\_LatLon} - Intermediate Atmospheric physics, 5 layers    Global configuration, on latitude longitude grid with 128x64x5 grid
393  Molteni physics package. Global configuration, 128x64x5 resolution.    points ($2.8^\circ{\rm degree}$ resolution).
394      
395    \item \textit{adjustment.128x64x1} Barotropic adjustment problem on
396      latitude longitude grid with 128x64 grid points ($2.8^\circ{\rm
397        degree}$ resolution).
398      
399    \item \textit{adjustment.cs-32x32x1} Barotropic adjustment problem on
400      cube sphere grid with 32x32 points per face ( roughly $2.8^\circ{\rm
401        degree}$ resolution).
402      
403    \item \textit{advect\_cs} Two-dimensional passive advection test on
404      cube sphere grid.
405      
406    \item \textit{advect\_xy} Two-dimensional (horizontal plane) passive
407      advection test on Cartesian grid.
408      
409    \item \textit{advect\_yz} Two-dimensional (vertical plane) passive
410      advection test on Cartesian grid.
411      
412    \item \textit{carbon} Simple passive tracer experiment. Includes
413      derivative calculation. Described in detail in section
414      \ref{sect:eg-carbon-ad}.
415    
416    \item \textit{flt\_example} Example of using float package.
417      
418    \item \textit{global\_ocean.90x40x15} Global circulation with GM, flux
419      boundary conditions and poles.
420    
421    \item \textit{global\_ocean\_pressure} Global circulation in pressure
422      coordinate (non-Boussinesq ocean model). Described in detail in
423      section \ref{sect:eg-globalpressure}.
424      
425    \item \textit{solid-body.cs-32x32x1} Solid body rotation test for cube
426      sphere grid.
427    
428  \item \textit{adjustment.128x64x1}  \end{enumerate}
429    
430  \item \textit{adjustment.cs-32x32x1}  \subsection{Directory structure of model examples}
 \end{itemize}  
   
 \subsubsection{Directory structure of model examples}  
431    
432  Each example directory has the following subdirectories:  Each example directory has the following subdirectories:
433    
434  \begin{itemize}  \begin{itemize}
435  \item \textit{code}: contains the code particular to the example. At a  \item \textit{code}: contains the code particular to the example. At a
436  minimum, this directory includes the following files:    minimum, this directory includes the following files:
   
 \begin{itemize}  
 \item \textit{code/CPP\_EEOPTIONS.h}: declares CPP keys relative to the  
 ``execution environment'' part of the code. The default version is located  
 in \textit{eesupp/inc}.  
   
 \item \textit{code/CPP\_OPTIONS.h}: declares CPP keys relative to the  
 ``numerical model'' part of the code. The default version is located in  
 \textit{model/inc}.  
   
 \item \textit{code/SIZE.h}: declares size of underlying computational grid.  
 The default version is located in \textit{model/inc}.  
 \end{itemize}  
   
 In addition, other include files and subroutines might be present in \textit{%  
 code} depending on the particular experiment. See section 2 for more details.  
   
 \item \textit{input}: contains the input data files required to run the  
 example. At a mimimum, the \textit{input} directory contains the following  
 files:  
   
 \begin{itemize}  
 \item \textit{input/data}: this file, written as a namelist, specifies the  
 main parameters for the experiment.  
437    
438  \item \textit{input/data.pkg}: contains parameters relative to the packages    \begin{itemize}
439  used in the experiment.    \item \textit{code/CPP\_EEOPTIONS.h}: declares CPP keys relative to
440        the ``execution environment'' part of the code. The default
441        version is located in \textit{eesupp/inc}.
442      
443      \item \textit{code/CPP\_OPTIONS.h}: declares CPP keys relative to
444        the ``numerical model'' part of the code. The default version is
445        located in \textit{model/inc}.
446      
447      \item \textit{code/SIZE.h}: declares size of underlying
448        computational grid.  The default version is located in
449        \textit{model/inc}.
450      \end{itemize}
451      
452      In addition, other include files and subroutines might be present in
453      \textit{code} depending on the particular experiment. See Section 2
454      for more details.
455      
456    \item \textit{input}: contains the input data files required to run
457      the example. At a minimum, the \textit{input} directory contains the
458      following files:
459    
460      \begin{itemize}
461      \item \textit{input/data}: this file, written as a namelist,
462        specifies the main parameters for the experiment.
463      
464      \item \textit{input/data.pkg}: contains parameters relative to the
465        packages used in the experiment.
466      
467      \item \textit{input/eedata}: this file contains ``execution
468        environment'' data. At present, this consists of a specification
469        of the number of threads to use in $X$ and $Y$ under multithreaded
470        execution.
471      \end{itemize}
472      
473      In addition, you will also find in this directory the forcing and
474      topography files as well as the files describing the initial state
475      of the experiment.  This varies from experiment to experiment. See
476      section 2 for more details.
477    
478    \item \textit{results}: this directory contains the output file
479      \textit{output.txt} produced by the simulation example. This file is
480      useful for comparison with your own output when you run the
481      experiment.
482    \end{itemize}
483    
484    Once you have chosen the example you want to run, you are ready to
485    compile the code.
486    
487    \section{Building the code}
488    \label{sect:buildingCode}
489    
490    To compile the code, we use the {\em make} program. This uses a file
491    ({\em Makefile}) that allows us to pre-process source files, specify
492    compiler and optimization options and also figures out any file
493    dependencies. We supply a script ({\em genmake2}), described in
494    section \ref{sect:genmake}, that automatically creates the {\em
495      Makefile} for you. You then need to build the dependencies and
496    compile the code.
497    
498    As an example, let's assume that you want to build and run experiment
499    \textit{verification/exp2}. The are multiple ways and places to
500    actually do this but here let's build the code in
501    \textit{verification/exp2/input}:
502    \begin{verbatim}
503    % cd verification/exp2/input
504    \end{verbatim}
505    First, build the {\em Makefile}:
506    \begin{verbatim}
507    % ../../../tools/genmake2 -mods=../code
508    \end{verbatim}
509    The command line option tells {\em genmake} to override model source
510    code with any files in the directory {\em ./code/}.
511    
512  \item \textit{input/eedata}: this file contains ``execution environment''  On many systems, the {\em genmake2} program will be able to
513  data. At present, this consists of a specification of the number of threads  automatically recognize the hardware, find compilers and other tools
514  to use in $X$ and $Y$ under multithreaded execution.  within the user's path (``echo \$PATH''), and then choose an
515  \end{itemize}  appropriate set of options from the files contained in the {\em
516      tools/build\_options} directory.  Under some circumstances, a user
517    may have to create a new ``optfile'' in order to specify the exact
518    combination of compiler, compiler flags, libraries, and other options
519    necessary to build a particular configuration of MITgcm.  In such
520    cases, it is generally helpful to read the existing ``optfiles'' and
521    mimic their syntax.
522    
523    Through the MITgcm-support list, the MITgcm developers are willing to
524    provide help writing or modifing ``optfiles''.  And we encourage users
525    to post new ``optfiles'' (particularly ones for new machines or
526    architectures) to the
527    \begin{rawhtml} <A href=''mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
528    MITgcm-support@mitgcm.org
529    \begin{rawhtml} </A> \end{rawhtml}
530    list.
531    
532  In addition, you will also find in this directory the forcing and topography  To specify an optfile to {\em genmake2}, the syntax is:
533  files as well as the files describing the initial state of the experiment.  \begin{verbatim}
534  This varies from experiment to experiment. See section 2 for more details.  % ../../../tools/genmake2 -mods=../code -of /path/to/optfile
535    \end{verbatim}
 \item \textit{results}: this directory contains the output file \textit{%  
 output.txt} produced by the simulation example. This file is useful for  
 comparison with your own output when you run the experiment.  
 \end{itemize}  
536    
537  Once you have chosen the example you want to run, you are ready to compile  Once a {\em Makefile} has been generated, we create the dependencies:
538  the code.  \begin{verbatim}
539    % make depend
540    \end{verbatim}
541    This modifies the {\em Makefile} by attaching a [long] list of files
542    upon which other files depend. The purpose of this is to reduce
543    re-compilation if and when you start to modify the code. The {\tt make
544      depend} command also creates links from the model source to this
545    directory.
546    
547  \subsection{Compiling the code}  Next compile the code:
548    \begin{verbatim}
549    % make
550    \end{verbatim}
551    The {\tt make} command creates an executable called \textit{mitgcmuv}.
552    Additional make ``targets'' are defined within the makefile to aid in
553    the production of adjoint and other versions of MITgcm.
554    
555  \subsubsection{The script \textit{genmake}}  Now you are ready to run the model. General instructions for doing so are
556    given in section \ref{sect:runModel}. Here, we can run the model with:
557    \begin{verbatim}
558    ./mitgcmuv > output.txt
559    \end{verbatim}
560    where we are re-directing the stream of text output to the file {\em
561    output.txt}.
562    
 To compile the code, use the script \textit{genmake} located in the \textit{%  
 tools} directory. \textit{genmake} is a script that generates the makefile.  
 It has been written so that the code can be compiled on a wide diversity of  
 machines and systems. However, if it doesn't work the first time on your  
 platform, you might need to edit certain lines of \textit{genmake} in the  
 section containing the setups for the different machines. The file is  
 structured like this:  
 \begin{verbatim}  
         .  
         .  
         .  
 general instructions (machine independent)  
         .  
         .  
         .  
     - setup machine 1  
     - setup machine 2  
     - setup machine 3  
     - setup machine 4  
        etc  
         .  
         .  
         .  
 \end{verbatim}  
   
 For example, the setup corresponding to a DEC alpha machine is reproduced  
 here:  
 \begin{verbatim}  
   case OSF1+mpi:  
     echo "Configuring for DEC Alpha"  
     set CPP        = ( '/usr/bin/cpp -P' )  
     set DEFINES    = ( ${DEFINES}  '-DTARGET_DEC -DWORDLENGTH=1' )  
     set KPP        = ( 'kapf' )  
     set KPPFILES   = ( 'main.F' )  
     set KFLAGS1    = ( '-scan=132 -noconc -cmp=' )  
     set FC         = ( 'f77' )  
     set FFLAGS     = ( '-convert big_endian -r8 -extend_source -automatic -call_shared -notransform_loops -align dcommons' )  
     set FOPTIM     = ( '-O5 -fast -tune host -inline all' )  
     set NOOPTFLAGS = ( '-O0' )  
     set LIBS       = ( '-lfmpi -lmpi -lkmp_osfp10 -pthread' )  
     set NOOPTFILES = ( 'barrier.F different_multiple.F external_fields_load.F')  
     set RMFILES    = ( '*.p.out' )  
     breaksw  
 \end{verbatim}  
   
 Typically, these are the lines that you might need to edit to make \textit{%  
 genmake} work on your platform if it doesn't work the first time. \textit{%  
 genmake} understands several options that are described here:  
563    
564  \begin{itemize}  \subsection{Building/compiling the code elsewhere}
 \item -rootdir=dir  
565    
566  indicates where the model root directory is relative to the directory where  In the example above (section \ref{sect:buildingCode}) we built the
567  you are compiling. This option is not needed if you compile in the \textit{%  executable in the {\em input} directory of the experiment for
568  bin} directory (which is the default compilation directory) or within the  convenience. You can also configure and compile the code in other
569  \textit{verification} tree.  locations, for example on a scratch disk with out having to copy the
570    entire source tree. The only requirement to do so is you have {\tt
571      genmake2} in your path or you know the absolute path to {\tt
572      genmake2}.
573    
574  \item -mods=dir1,dir2,...  The following sections outline some possible methods of organizing
575    your source and data.
576    
577  indicates the relative or absolute paths directories where the sources  \subsubsection{Building from the {\em ../code directory}}
 should take precedence over the default versions (located in \textit{model},  
 \textit{eesupp},...). Typically, this option is used when running the  
 examples, see below.  
578    
579  \item -enable=pkg1,pkg2,...  This is just as simple as building in the {\em input/} directory:
580    \begin{verbatim}
581    % cd verification/exp2/code
582    % ../../../tools/genmake2
583    % make depend
584    % make
585    \end{verbatim}
586    However, to run the model the executable ({\em mitgcmuv}) and input
587    files must be in the same place. If you only have one calculation to make:
588    \begin{verbatim}
589    % cd ../input
590    % cp ../code/mitgcmuv ./
591    % ./mitgcmuv > output.txt
592    \end{verbatim}
593    or if you will be making multiple runs with the same executable:
594    \begin{verbatim}
595    % cd ../
596    % cp -r input run1
597    % cp code/mitgcmuv run1
598    % cd run1
599    % ./mitgcmuv > output.txt
600    \end{verbatim}
601    
602  enables packages source code \textit{pkg1}, \textit{pkg2},... when creating  \subsubsection{Building from a new directory}
 the makefile.  
603    
604  \item -disable=pkg1,pkg2,...  Since the {\em input} directory contains input files it is often more
605    useful to keep {\em input} pristine and build in a new directory
606    within {\em verification/exp2/}:
607    \begin{verbatim}
608    % cd verification/exp2
609    % mkdir build
610    % cd build
611    % ../../../tools/genmake2 -mods=../code
612    % make depend
613    % make
614    \end{verbatim}
615    This builds the code exactly as before but this time you need to copy
616    either the executable or the input files or both in order to run the
617    model. For example,
618    \begin{verbatim}
619    % cp ../input/* ./
620    % ./mitgcmuv > output.txt
621    \end{verbatim}
622    or if you tend to make multiple runs with the same executable then
623    running in a new directory each time might be more appropriate:
624    \begin{verbatim}
625    % cd ../
626    % mkdir run1
627    % cp build/mitgcmuv run1/
628    % cp input/* run1/
629    % cd run1
630    % ./mitgcmuv > output.txt
631    \end{verbatim}
632    
633  disables packages source code \textit{pkg1}, \textit{pkg2},... when creating  \subsubsection{Building on a scratch disk}
 the makefile.  
634    
635  \item -platform=machine  Model object files and output data can use up large amounts of disk
636    space so it is often the case that you will be operating on a large
637    scratch disk. Assuming the model source is in {\em ~/MITgcm} then the
638    following commands will build the model in {\em /scratch/exp2-run1}:
639    \begin{verbatim}
640    % cd /scratch/exp2-run1
641    % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
642      -mods=~/MITgcm/verification/exp2/code
643    % make depend
644    % make
645    \end{verbatim}
646    To run the model here, you'll need the input files:
647    \begin{verbatim}
648    % cp ~/MITgcm/verification/exp2/input/* ./
649    % ./mitgcmuv > output.txt
650    \end{verbatim}
651    
652  specifies the platform for which you want the makefile. In general, you  As before, you could build in one directory and make multiple runs of
653  won't need this option. \textit{genmake} will select the right machine for  the one experiment:
654  you (the one you're working on!). However, this option is useful if you have  \begin{verbatim}
655  a choice of several compilers on one machine and you want to use the one  % cd /scratch/exp2
656  that is not the default (ex: \texttt{pgf77} instead of \texttt{f77} under  % mkdir build
657  Linux).  % cd build
658    % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
659      -mods=~/MITgcm/verification/exp2/code
660    % make depend
661    % make
662    % cd ../
663    % cp -r ~/MITgcm/verification/exp2/input run2
664    % cd run2
665    % ./mitgcmuv > output.txt
666    \end{verbatim}
667    
 \item -mpi  
668    
 this is used when you want to run the model in parallel processing mode  
 under mpi (see section on parallel computation for more details).  
669    
670  \item -jam  \subsection{Using \textit{genmake2}}
671    \label{sect:genmake}
672    
673  this is used when you want to run the model in parallel processing mode  To compile the code, first use the program \texttt{genmake2} (located
674  under jam (see section on parallel computation for more details).  in the \textit{tools} directory) to generate a Makefile.
675  \end{itemize}  \texttt{genmake2} is a shell script written to work with all
676    ``sh''--compatible shells including bash v1, bash v2, and Bourne.
677    Internally, \texttt{genmake2} determines the locations of needed
678    files, the compiler, compiler options, libraries, and Unix tools.  It
679    relies upon a number of ``optfiles'' located in the {\em
680      tools/build\_options} directory.
681    
682    The purpose of the optfiles is to provide all the compilation options
683    for particular ``platforms'' (where ``platform'' roughly means the
684    combination of the hardware and the compiler) and code configurations.
685    Given the combinations of possible compilers and library dependencies
686    ({\it eg.}  MPI and NetCDF) there may be numerous optfiles available
687    for a single machine.  The naming scheme for the majority of the
688    optfiles shipped with the code is
689    \begin{center}
690      {\bf OS\_HARDWARE\_COMPILER }
691    \end{center}
692    where
693    \begin{description}
694    \item[OS] is the name of the operating system (generally the
695      lower-case output of the {\tt 'uname'} command)
696    \item[HARDWARE] is a string that describes the CPU type and
697      corresponds to output from the  {\tt 'uname -m'} command:
698      \begin{description}
699      \item[ia32] is for ``x86'' machines such as i386, i486, i586, i686,
700        and athlon
701      \item[ia64] is for Intel IA64 systems (eg. Itanium, Itanium2)
702      \item[amd64] is AMD x86\_64 systems
703      \item[ppc] is for Mac PowerPC systems
704      \end{description}
705    \item[COMPILER] is the compiler name (generally, the name of the
706      FORTRAN executable)
707    \end{description}
708    
709    In many cases, the default optfiles are sufficient and will result in
710    usable Makefiles.  However, for some machines or code configurations,
711    new ``optfiles'' must be written. To create a new optfile, it is
712    generally best to start with one of the defaults and modify it to suit
713    your needs.  Like \texttt{genmake2}, the optfiles are all written
714    using a simple ``sh''--compatible syntax.  While nearly all variables
715    used within \texttt{genmake2} may be specified in the optfiles, the
716    critical ones that should be defined are:
717    
718    \begin{description}
719    \item[FC] the FORTRAN compiler (executable) to use
720    \item[DEFINES] the command-line DEFINE options passed to the compiler
721    \item[CPP] the C pre-processor to use
722    \item[NOOPTFLAGS] options flags for special files that should not be
723      optimized
724    \end{description}
725    
726  For some of the examples, there is a file called \textit{.genmakerc} in the  For example, the optfile for a typical Red Hat Linux machine (``ia32''
727  \textit{input} directory that has the relevant \textit{genmake} options for  architecture) using the GCC (g77) compiler is
 that particular example. In this way you don't need to type the options when  
 invoking \textit{genmake}.  
   
 \subsubsection{Compiling}  
   
 Let's assume that you want to run, say, example \textit{exp2} in the \textit{%  
 input} directory. To compile the code, type the following commands from the  
 model root tree:  
728  \begin{verbatim}  \begin{verbatim}
729  % cd verification/exp2/input  FC=g77
730  % ../../../tools/genmake  DEFINES='-D_BYTESWAPIO -DWORDLENGTH=4'
731  % make depend  CPP='cpp  -traditional -P'
732  % make  NOOPTFLAGS='-O0'
733    #  For IEEE, use the "-ffloat-store" option
734    if test "x$IEEE" = x ; then
735        FFLAGS='-Wimplicit -Wunused -Wuninitialized'
736        FOPTIM='-O3 -malign-double -funroll-loops'
737    else
738        FFLAGS='-Wimplicit -Wunused -ffloat-store'
739        FOPTIM='-O0 -malign-double'
740    fi
741  \end{verbatim}  \end{verbatim}
742    
743  If there is no \textit{.genmakerc} in the \textit{input} directory, you have  If you write an optfile for an unrepresented machine or compiler, you
744  to use the following options when invoking \textit{genmake}:  are strongly encouraged to submit the optfile to the MITgcm project
745  \begin{verbatim}  for inclusion.  Please send the file to the
746  % ../../../tools/genmake  -mods=../code  \begin{rawhtml} <A href="mail-to:MITgcm-support@mitgcm.org"> \end{rawhtml}
747  \end{verbatim}  \begin{center}
748      MITgcm-support@mitgcm.org
749    \end{center}
750    \begin{rawhtml} </A> \end{rawhtml}
751    mailing list.
752    
753  In addition, you will probably want to disable some of the packages. Taking  In addition to the optfiles, \texttt{genmake2} supports a number of
754  again the case of \textit{exp2}, the full \textit{genmake} command will  helpful command-line options.  A complete list of these options can be
755  probably look like this:  obtained from:
756  \begin{verbatim}  \begin{verbatim}
757  % ../../../tools/genmake  -mods=../code  -disable=kpp,gmredi,aim,...  % genmake2 -h
758  \end{verbatim}  \end{verbatim}
759    
760  The make command creates an executable called \textit{mitgcmuv}.  The most important command-line options are:
761    \begin{description}
762      
763    \item[\texttt{--optfile=/PATH/FILENAME}] specifies the optfile that
764      should be used for a particular build.
765      
766      If no "optfile" is specified (either through the command line or the
767      MITGCM\_OPTFILE environment variable), genmake2 will try to make a
768      reasonable guess from the list provided in {\em
769        tools/build\_options}.  The method used for making this guess is
770      to first determine the combination of operating system and hardware
771      (eg. "linux\_ia32") and then find a working FORTRAN compiler within
772      the user's path.  When these three items have been identified,
773      genmake2 will try to find an optfile that has a matching name.
774      
775    \item[\texttt{--pdepend=/PATH/FILENAME}] specifies the dependency file
776      used for packages.
777      
778      If not specified, the default dependency file {\em pkg/pkg\_depend}
779      is used.  The syntax for this file is parsed on a line-by-line basis
780      where each line containes either a comment ("\#") or a simple
781      "PKGNAME1 (+|-)PKGNAME2" pairwise rule where the "+" or "-" symbol
782      specifies a "must be used with" or a "must not be used with"
783      relationship, respectively.  If no rule is specified, then it is
784      assumed that the two packages are compatible and will function
785      either with or without each other.
786      
787    \item[\texttt{--pdefault='PKG1 PKG2 PKG3 ...'}] specifies the default
788      set of packages to be used.
789      
790      If not set, the default package list will be read from {\em
791        pkg/pkg\_default}
792      
793    \item[\texttt{--adof=/path/to/file}] specifies the "adjoint" or
794      automatic differentiation options file to be used.  The file is
795      analogous to the ``optfile'' defined above but it specifies
796      information for the AD build process.
797      
798      The default file is located in {\em
799        tools/adjoint\_options/adjoint\_default} and it defines the "TAF"
800      and "TAMC" compilers.  An alternate version is also available at
801      {\em tools/adjoint\_options/adjoint\_staf} that selects the newer
802      "STAF" compiler.  As with any compilers, it is helpful to have their
803      directories listed in your {\tt \$PATH} environment variable.
804      
805    \item[\texttt{--mods='DIR1 DIR2 DIR3 ...'}] specifies a list of
806      directories containing ``modifications''.  These directories contain
807      files with names that may (or may not) exist in the main MITgcm
808      source tree but will be overridden by any identically-named sources
809      within the ``MODS'' directories.
810      
811      The order of precedence for this "name-hiding" is as follows:
812      \begin{itemize}
813      \item ``MODS'' directories (in the order given)
814      \item Packages either explicitly specified or provided by default
815        (in the order given)
816      \item Packages included due to package dependencies (in the order
817        that that package dependencies are parsed)
818      \item The "standard dirs" (which may have been specified by the
819        ``-standarddirs'' option)
820      \end{itemize}
821      
822    \item[\texttt{--make=/path/to/gmake}] Due to the poor handling of
823      soft-links and other bugs common with the \texttt{make} versions
824      provided by commercial Unix vendors, GNU \texttt{make} (sometimes
825      called \texttt{gmake}) should be preferred.  This option provides a
826      means for specifying the make executable to be used.
827    
828    \end{description}
829    
830    
831    
832    \section{Running the model}
833    \label{sect:runModel}
834    
835    If compilation finished succesfuully (section \ref{sect:buildModel})
836    then an executable called {\em mitgcmuv} will now exist in the local
837    directory.
838    
839  Note that you can compile and run the code in another directory than \textit{%  To run the model as a single process (ie. not in parallel) simply
840  input}. You just need to make sure that you copy the input data files into  type:
 the directory where you want to run the model. For example to compile from  
 \textit{code}:  
841  \begin{verbatim}  \begin{verbatim}
842  % cd verification/exp2/code  % ./mitgcmuv
843  % ../../../tools/genmake  \end{verbatim}
844  % make depend  The ``./'' is a safe-guard to make sure you use the local executable
845  % make  in case you have others that exist in your path (surely odd if you
846    do!). The above command will spew out many lines of text output to
847    your screen.  This output contains details such as parameter values as
848    well as diagnostics such as mean Kinetic energy, largest CFL number,
849    etc. It is worth keeping this text output with the binary output so we
850    normally re-direct the {\em stdout} stream as follows:
851    \begin{verbatim}
852    % ./mitgcmuv > output.txt
853  \end{verbatim}  \end{verbatim}
854    
855  \subsection{Running the model}  For the example experiments in {\em verification}, an example of the
856    output is kept in {\em results/output.txt} for comparison. You can compare
857    your {\em output.txt} with this one to check that the set-up works.
858    
859    
 The first thing to do is to run the code by typing \textit{mitgcmuv} and see  
 what happens. You can compare what you get with what is in the \textit{%  
 results} directory. Unless noted otherwise, most examples are set up to run  
 for a few time steps only so that you can quickly figure out whether the  
 model is working or not.  
860    
861  \subsubsection{Output files}  \subsection{Output files}
862    
863  The model produces various output files. At a minimum, the instantaneous  The model produces various output files. At a minimum, the instantaneous
864  ``state'' of the model is written out, which is made of the following files:  ``state'' of the model is written out, which is made of the following files:
# Line 450  as the pickup files but are named differ Line 909  as the pickup files but are named differ
909  used to restart the model but are overwritten every other time they are  used to restart the model but are overwritten every other time they are
910  output to save disk space during long integrations.  output to save disk space during long integrations.
911    
912  \subsubsection{Looking at the output}  \subsection{Looking at the output}
913    
914  All the model data are written according to a ``meta/data'' file format.  All the model data are written according to a ``meta/data'' file format.
915  Each variable is associated with two files with suffix names \textit{.data}  Each variable is associated with two files with suffix names \textit{.data}
# Line 464  written in this format. The matlab scrip Line 923  written in this format. The matlab scrip
923  \textit{utils/matlab} under the root tree. The script \textit{rdmds.m} reads  \textit{utils/matlab} under the root tree. The script \textit{rdmds.m} reads
924  the data. Look at the comments inside the script to see how to use it.  the data. Look at the comments inside the script to see how to use it.
925    
926  \section{Code structure}  Some examples of reading and visualizing some output in {\em Matlab}:
927    \begin{verbatim}
928    % matlab
929    >> H=rdmds('Depth');
930    >> contourf(H');colorbar;
931    >> title('Depth of fluid as used by model');
932    
933    >> eta=rdmds('Eta',10);
934    >> imagesc(eta');axis ij;colorbar;
935    >> title('Surface height at iter=10');
936    
937    >> eta=rdmds('Eta',[0:10:100]);
938    >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end
939    \end{verbatim}
940    
941  \section{Doing it yourself: customizing the code}  \section{Doing it yourself: customizing the code}
942    
 \subsection{\protect\bigskip Configuration and setup}  
   
943  When you are ready to run the model in the configuration you want, the  When you are ready to run the model in the configuration you want, the
944  easiest thing is to use and adapt the setup of the case studies experiment  easiest thing is to use and adapt the setup of the case studies
945  (described previously) that is the closest to your configuration. Then, the  experiment (described previously) that is the closest to your
946  amount of setup will be minimized. In this section, we focus on the setup  configuration. Then, the amount of setup will be minimized. In this
947  relative to the ''numerical model'' part of the code (the setup relative to  section, we focus on the setup relative to the ``numerical model''
948  the ''execution environment'' part is covered in the parallel implementation  part of the code (the setup relative to the ``execution environment''
949  section) and on the variables and parameters that you are likely to change.  part is covered in the parallel implementation section) and on the
950    variables and parameters that you are likely to change.
951  The CPP keys relative to the ''numerical model'' part of the code are all  
952  defined and set in the file \textit{CPP\_OPTIONS.h }in the directory \textit{%  \subsection{Configuration and setup}
953  model/inc }or in one of the \textit{code }directories of the case study  
954  experiments under \textit{verification.} The model parameters are defined  The CPP keys relative to the ``numerical model'' part of the code are
955  and declared in the file \textit{model/inc/PARAMS.h }and their default  all defined and set in the file \textit{CPP\_OPTIONS.h }in the
956  values are set in the routine \textit{model/src/set\_defaults.F. }The  directory \textit{ model/inc }or in one of the \textit{code
957  default values can be modified in the namelist file \textit{data }which  }directories of the case study experiments under
958  needs to be located in the directory where you will run the model. The  \textit{verification.} The model parameters are defined and declared
959  parameters are initialized in the routine \textit{model/src/ini\_parms.F}.  in the file \textit{model/inc/PARAMS.h }and their default values are
960  Look at this routine to see in what part of the namelist the parameters are  set in the routine \textit{model/src/set\_defaults.F. }The default
961  located.  values can be modified in the namelist file \textit{data }which needs
962    to be located in the directory where you will run the model. The
963  In what follows the parameters are grouped into categories related to the  parameters are initialized in the routine
964  computational domain, the equations solved in the model, and the simulation  \textit{model/src/ini\_parms.F}.  Look at this routine to see in what
965  controls.  part of the namelist the parameters are located.
966    
967  \subsubsection{Computational domain, geometry and time-discretization}  In what follows the parameters are grouped into categories related to
968    the computational domain, the equations solved in the model, and the
969  \begin{itemize}  simulation controls.
970  \item dimensions  
971  \end{itemize}  \subsection{Computational domain, geometry and time-discretization}
972    
973  The number of points in the x, y,\textit{\ }and r\textit{\ }directions are  \begin{description}
974  represented by the variables \textbf{sNx}\textit{, }\textbf{sNy}\textit{, }%  \item[dimensions] \
975  and \textbf{Nr}\textit{\ }respectively which are declared and set in the    
976  file \textit{model/inc/SIZE.h. }(Again, this assumes a mono-processor    The number of points in the x, y, and r directions are represented
977  calculation. For multiprocessor calculations see section on parallel    by the variables \textbf{sNx}, \textbf{sNy} and \textbf{Nr}
978  implementation.)    respectively which are declared and set in the file
979      \textit{model/inc/SIZE.h}.  (Again, this assumes a mono-processor
980  \begin{itemize}    calculation. For multiprocessor calculations see the section on
981  \item grid    parallel implementation.)
982  \end{itemize}  
983    \item[grid] \
984  Three different grids are available: cartesian, spherical polar, and    
985  curvilinear (including the cubed sphere). The grid is set through the    Three different grids are available: cartesian, spherical polar, and
986  logical variables \textbf{usingCartesianGrid}\textit{, }\textbf{%    curvilinear (which includes the cubed sphere). The grid is set
987  usingSphericalPolarGrid}\textit{, }and \textit{\ }\textbf{%    through the logical variables \textbf{usingCartesianGrid},
988  usingCurvilinearGrid}\textit{. }In the case of spherical and curvilinear    \textbf{usingSphericalPolarGrid}, and \textbf{usingCurvilinearGrid}.
989  grids, the southern boundary is defined through the variable \textbf{phiMin}%    In the case of spherical and curvilinear grids, the southern
990  \textit{\ }which corresponds to the latitude of the southern most cell face    boundary is defined through the variable \textbf{phiMin} which
991  (in degrees). The resolution along the x and y directions is controlled by    corresponds to the latitude of the southern most cell face (in
992  the 1D arrays \textbf{delx}\textit{\ }and \textbf{dely}\textit{\ }(in meters    degrees). The resolution along the x and y directions is controlled
993  in the case of a cartesian grid, in degrees otherwise). The vertical grid    by the 1D arrays \textbf{delx} and \textbf{dely} (in meters in the
994  spacing is set through the 1D array \textbf{delz }for the ocean (in meters)    case of a cartesian grid, in degrees otherwise).  The vertical grid
995  or \textbf{delp}\textit{\ }for the atmosphere (in Pa). The variable \textbf{%    spacing is set through the 1D array \textbf{delz} for the ocean (in
996  Ro\_SeaLevel} represents the standard position of Sea-Level in ''R''    meters) or \textbf{delp} for the atmosphere (in Pa).  The variable
997  coordinate. This is typically set to 0m for the ocean (default value) and 10$%    \textbf{Ro\_SeaLevel} represents the standard position of Sea-Level
998  ^{5}$Pa for the atmosphere. For the atmosphere, also set the logical    in ``R'' coordinate. This is typically set to 0m for the ocean
999  variable \textbf{groundAtK1} to '.\texttt{TRUE}.'. which put the first level    (default value) and 10$^{5}$Pa for the atmosphere. For the
1000  (k=1) at the lower boundary (ground).    atmosphere, also set the logical variable \textbf{groundAtK1} to
1001      \texttt{'.TRUE.'} which puts the first level (k=1) at the lower
1002  For the cartesian grid case, the Coriolis parameter $f$ is set through the    boundary (ground).
1003  variables \textbf{f0}\textit{\ }and \textbf{beta}\textit{\ }which correspond    
1004  to the reference Coriolis parameter (in s$^{-1}$) and $\frac{\partial f}{%    For the cartesian grid case, the Coriolis parameter $f$ is set
1005  \partial y}$(in m$^{-1}$s$^{-1}$) respectively. If \textbf{beta }\textit{\ }%    through the variables \textbf{f0} and \textbf{beta} which correspond
1006  is set to a nonzero value, \textbf{f0}\textit{\ }is the value of $f$ at the    to the reference Coriolis parameter (in s$^{-1}$) and
1007  southern edge of the domain.    $\frac{\partial f}{ \partial y}$(in m$^{-1}$s$^{-1}$) respectively.
1008      If \textbf{beta } is set to a nonzero value, \textbf{f0} is the
1009  \begin{itemize}    value of $f$ at the southern edge of the domain.
1010  \item topography - full and partial cells  
1011  \end{itemize}  \item[topography - full and partial cells] \
1012      
1013  The domain bathymetry is read from a file that contains a 2D (x,y) map of    The domain bathymetry is read from a file that contains a 2D (x,y)
1014  depths (in m) for the ocean or pressures (in Pa) for the atmosphere. The    map of depths (in m) for the ocean or pressures (in Pa) for the
1015  file name is represented by the variable \textbf{bathyFile}\textit{. }The    atmosphere. The file name is represented by the variable
1016  file is assumed to contain binary numbers giving the depth (pressure) of the    \textbf{bathyFile}. The file is assumed to contain binary numbers
1017  model at each grid cell, ordered with the x coordinate varying fastest. The    giving the depth (pressure) of the model at each grid cell, ordered
1018  points are ordered from low coordinate to high coordinate for both axes. The    with the x coordinate varying fastest. The points are ordered from
1019  model code applies without modification to enclosed, periodic, and double    low coordinate to high coordinate for both axes. The model code
1020  periodic domains. Periodicity is assumed by default and is suppressed by    applies without modification to enclosed, periodic, and double
1021  setting the depths to 0m for the cells at the limits of the computational    periodic domains. Periodicity is assumed by default and is
1022  domain (note: not sure this is the case for the atmosphere). The precision    suppressed by setting the depths to 0m for the cells at the limits
1023  with which to read the binary data is controlled by the integer variable    of the computational domain (note: not sure this is the case for the
1024  \textbf{readBinaryPrec }which can take the value \texttt{32} (single    atmosphere). The precision with which to read the binary data is
1025  precision) or \texttt{64} (double precision). See the matlab program \textit{%    controlled by the integer variable \textbf{readBinaryPrec} which can
1026  gendata.m }in the \textit{input }directories under \textit{verification }to    take the value \texttt{32} (single precision) or \texttt{64} (double
1027  see how the bathymetry files are generated for the case study experiments.    precision). See the matlab program \textit{gendata.m} in the
1028      \textit{input} directories under \textit{verification} to see how
1029  To use the partial cell capability, the variable \textbf{hFacMin}\textit{\ }%    the bathymetry files are generated for the case study experiments.
1030  needs to be set to a value between 0 and 1 (it is set to 1 by default)    
1031  corresponding to the minimum fractional size of the cell. For example if the    To use the partial cell capability, the variable \textbf{hFacMin}
1032  bottom cell is 500m thick and \textbf{hFacMin}\textit{\ }is set to 0.1, the    needs to be set to a value between 0 and 1 (it is set to 1 by
1033  actual thickness of the cell (i.e. used in the code) can cover a range of    default) corresponding to the minimum fractional size of the cell.
1034  discrete values 50m apart from 50m to 500m depending on the value of the    For example if the bottom cell is 500m thick and \textbf{hFacMin} is
1035  bottom depth (in \textbf{bathyFile}) at this point.    set to 0.1, the actual thickness of the cell (i.e. used in the code)
1036      can cover a range of discrete values 50m apart from 50m to 500m
1037  Note that the bottom depths (or pressures) need not coincide with the models    depending on the value of the bottom depth (in \textbf{bathyFile})
1038  levels as deduced from \textbf{delz}\textit{\ }or\textit{\ }\textbf{delp}%    at this point.
1039  \textit{. }The model will interpolate the numbers in \textbf{bathyFile}%    
1040  \textit{\ }so that they match the levels obtained from \textbf{delz}\textit{%    Note that the bottom depths (or pressures) need not coincide with
1041  \ }or\textit{\ }\textbf{delp}\textit{\ }and \textbf{hFacMin}\textit{. }    the models levels as deduced from \textbf{delz} or \textbf{delp}.
1042      The model will interpolate the numbers in \textbf{bathyFile} so that
1043  (Note: the atmospheric case is a bit more complicated than what is written    they match the levels obtained from \textbf{delz} or \textbf{delp}
1044  here I think. To come soon...)    and \textbf{hFacMin}.
1045      
1046  \begin{itemize}    (Note: the atmospheric case is a bit more complicated than what is
1047  \item time-discretization    written here I think. To come soon...)
1048  \end{itemize}  
1049    \item[time-discretization] \
1050  The time steps are set through the real variables \textbf{deltaTMom }and    
1051  \textbf{deltaTtracer }(in s) which represent the time step for the momentum    The time steps are set through the real variables \textbf{deltaTMom}
1052  and tracer equations, respectively. For synchronous integrations, simply set    and \textbf{deltaTtracer} (in s) which represent the time step for
1053  the two variables to the same value (or you can prescribe one time step only    the momentum and tracer equations, respectively. For synchronous
1054  through the variable \textbf{deltaT}). The Adams-Bashforth stabilizing    integrations, simply set the two variables to the same value (or you
1055  parameter is set through the variable \textbf{abEps }(dimensionless). The    can prescribe one time step only through the variable
1056  stagger baroclinic time stepping can be activated by setting the logical    \textbf{deltaT}). The Adams-Bashforth stabilizing parameter is set
1057  variable \textbf{staggerTimeStep }to '.\texttt{TRUE}.'.    through the variable \textbf{abEps} (dimensionless). The stagger
1058      baroclinic time stepping can be activated by setting the logical
1059  \subsubsection{Equation of state}    variable \textbf{staggerTimeStep} to \texttt{'.TRUE.'}.
1060    
1061  First, because the model equations are written in terms of perturbations, a  \end{description}
1062  reference thermodynamic state needs to be specified. This is done through  
1063  the 1D arrays \textbf{tRef}\textit{\ }and \textbf{sRef}. \textbf{tRef }%  
1064  specifies the reference potential temperature profile (in $^{o}$C for  \subsection{Equation of state}
1065  the ocean and $^{o}$K for the atmosphere) starting from the level  
1066  k=1. Similarly, \textbf{sRef}\textit{\ }specifies the reference salinity  First, because the model equations are written in terms of
1067  profile (in ppt) for the ocean or the reference specific humidity profile  perturbations, a reference thermodynamic state needs to be specified.
1068  (in g/kg) for the atmosphere.  This is done through the 1D arrays \textbf{tRef} and \textbf{sRef}.
1069    \textbf{tRef} specifies the reference potential temperature profile
1070  The form of the equation of state is controlled by the character variables  (in $^{o}$C for the ocean and $^{o}$K for the atmosphere) starting
1071  \textbf{buoyancyRelation}\textit{\ }and \textbf{eosType}\textit{. }\textbf{%  from the level k=1. Similarly, \textbf{sRef} specifies the reference
1072  buoyancyRelation}\textit{\ }is set to '\texttt{OCEANIC}' by default and  salinity profile (in ppt) for the ocean or the reference specific
1073  needs to be set to '\texttt{ATMOSPHERIC}' for atmosphere simulations. In  humidity profile (in g/kg) for the atmosphere.
1074  this case, \textbf{eosType}\textit{\ }must be set to '\texttt{IDEALGAS}'.  
1075  For the ocean, two forms of the equation of state are available: linear (set  The form of the equation of state is controlled by the character
1076  \textbf{eosType}\textit{\ }to '\texttt{LINEAR}') and a polynomial  variables \textbf{buoyancyRelation} and \textbf{eosType}.
1077  approximation to the full nonlinear equation ( set \textbf{eosType}\textit{\  \textbf{buoyancyRelation} is set to \texttt{'OCEANIC'} by default and
1078  }to '\texttt{POLYNOMIAL}'). In the linear case, you need to specify the  needs to be set to \texttt{'ATMOSPHERIC'} for atmosphere simulations.
1079  thermal and haline expansion coefficients represented by the variables  In this case, \textbf{eosType} must be set to \texttt{'IDEALGAS'}.
1080  \textbf{tAlpha}\textit{\ }(in K$^{-1}$) and \textbf{sBeta}\textit{\ }(in ppt$%  For the ocean, two forms of the equation of state are available:
1081  ^{-1}$). For the nonlinear case, you need to generate a file of polynomial  linear (set \textbf{eosType} to \texttt{'LINEAR'}) and a polynomial
1082  coefficients called \textit{POLY3.COEFFS. }To do this, use the program  approximation to the full nonlinear equation ( set \textbf{eosType} to
1083  \textit{utils/knudsen2/knudsen2.f }under the model tree (a Makefile is  \texttt{'POLYNOMIAL'}). In the linear case, you need to specify the
1084  available in the same directory and you will need to edit the number and the  thermal and haline expansion coefficients represented by the variables
1085  values of the vertical levels in \textit{knudsen2.f }so that they match  \textbf{tAlpha} (in K$^{-1}$) and \textbf{sBeta} (in ppt$^{-1}$). For
1086  those of your configuration). \textit{\ }  the nonlinear case, you need to generate a file of polynomial
1087    coefficients called \textit{POLY3.COEFFS}. To do this, use the program
1088  \subsubsection{Momentum equations}  \textit{utils/knudsen2/knudsen2.f} under the model tree (a Makefile is
1089    available in the same directory and you will need to edit the number
1090  In this section, we only focus for now on the parameters that you are likely  and the values of the vertical levels in \textit{knudsen2.f} so that
1091  to change, i.e. the ones relative to forcing and dissipation for example.  they match those of your configuration).
1092  The details relevant to the vector-invariant form of the equations and the  
1093  various advection schemes are not covered for the moment. We assume that you  There there are also higher polynomials for the equation of state:
1094  use the standard form of the momentum equations (i.e. the flux-form) with  \begin{description}
1095  the default advection scheme. Also, there are a few logical variables that  \item[\texttt{'UNESCO'}:] The UNESCO equation of state formula of
1096  allow you to turn on/off various terms in the momentum equation. These    Fofonoff and Millard \cite{fofonoff83}. This equation of state
1097  variables are called \textbf{momViscosity, momAdvection, momForcing,    assumes in-situ temperature, which is not a model variable; {\em its
1098  useCoriolis, momPressureForcing, momStepping}\textit{, }and \textit{\ }%      use is therefore discouraged, and it is only listed for
1099  \textbf{metricTerms }and are assumed to be set to '.\texttt{TRUE}.' here.      completeness}.
1100  Look at the file \textit{model/inc/PARAMS.h }for a precise definition of  \item[\texttt{'JMD95Z'}:] A modified UNESCO formula by Jackett and
1101  these variables.    McDougall \cite{jackett95}, which uses the model variable potential
1102      temperature as input. The \texttt{'Z'} indicates that this equation
1103  \begin{itemize}    of state uses a horizontally and temporally constant pressure
1104  \item initialization    $p_{0}=-g\rho_{0}z$.
1105  \end{itemize}  \item[\texttt{'JMD95P'}:] A modified UNESCO formula by Jackett and
1106      McDougall \cite{jackett95}, which uses the model variable potential
1107  The velocity components are initialized to 0 unless the simulation is    temperature as input. The \texttt{'P'} indicates that this equation
1108  starting from a pickup file (see section on simulation control parameters).    of state uses the actual hydrostatic pressure of the last time
1109      step. Lagging the pressure in this way requires an additional pickup
1110  \begin{itemize}    file for restarts.
1111  \item forcing  \item[\texttt{'MDJWF'}:] The new, more accurate and less expensive
1112  \end{itemize}    equation of state by McDougall et~al. \cite{mcdougall03}. It also
1113      requires lagging the pressure and therefore an additional pickup
1114  This section only applies to the ocean. You need to generate wind-stress    file for restarts.
1115  data into two files \textbf{zonalWindFile}\textit{\ }and \textbf{%  \end{description}
1116  meridWindFile }corresponding to the zonal and meridional components of the  For none of these options an reference profile of temperature or
1117  wind stress, respectively (if you want the stress to be along the direction  salinity is required.
1118  of only one of the model horizontal axes, you only need to generate one  
1119  file). The format of the files is similar to the bathymetry file. The zonal  \subsection{Momentum equations}
1120  (meridional) stress data are assumed to be in Pa and located at U-points  
1121  (V-points). As for the bathymetry, the precision with which to read the  In this section, we only focus for now on the parameters that you are
1122  binary data is controlled by the variable \textbf{readBinaryPrec}.\textbf{\ }  likely to change, i.e. the ones relative to forcing and dissipation
1123  See the matlab program \textit{gendata.m }in the \textit{input }directories  for example.  The details relevant to the vector-invariant form of the
1124  under \textit{verification }to see how simple analytical wind forcing data  equations and the various advection schemes are not covered for the
1125  are generated for the case study experiments.  moment. We assume that you use the standard form of the momentum
1126    equations (i.e. the flux-form) with the default advection scheme.
1127  There is also the possibility of prescribing time-dependent periodic  Also, there are a few logical variables that allow you to turn on/off
1128  forcing. To do this, concatenate the successive time records into a single  various terms in the momentum equation. These variables are called
1129  file (for each stress component) ordered in a (x, y, t) fashion and set the  \textbf{momViscosity, momAdvection, momForcing, useCoriolis,
1130  following variables: \textbf{periodicExternalForcing }to '.\texttt{TRUE}.',    momPressureForcing, momStepping} and \textbf{metricTerms }and are
1131  \textbf{externForcingPeriod }to the period (in s) of which the forcing  assumed to be set to \texttt{'.TRUE.'} here.  Look at the file
1132  varies (typically 1 month), and \textbf{externForcingCycle }to the repeat  \textit{model/inc/PARAMS.h }for a precise definition of these
1133  time (in s) of the forcing (typically 1 year -- note: \textbf{%  variables.
1134  externForcingCycle }must be a multiple of \textbf{externForcingPeriod}).  
1135  With these variables set up, the model will interpolate the forcing linearly  \begin{description}
1136  at each iteration.  \item[initialization] \
1137      
1138  \begin{itemize}    The velocity components are initialized to 0 unless the simulation
1139  \item dissipation    is starting from a pickup file (see section on simulation control
1140  \end{itemize}    parameters).
1141    
1142  The lateral eddy viscosity coefficient is specified through the variable  \item[forcing] \
1143  \textbf{viscAh}\textit{\ }(in m$^{2}$s$^{-1}$). The vertical eddy viscosity    
1144  coefficient is specified through the variable \textbf{viscAz }(in m$^{2}$s$%    This section only applies to the ocean. You need to generate
1145  ^{-1}$) for the ocean and \textbf{viscAp}\textit{\ }(in Pa$^{2}$s$^{-1}$)    wind-stress data into two files \textbf{zonalWindFile} and
1146  for the atmosphere. The vertical diffusive fluxes can be computed implicitly    \textbf{meridWindFile} corresponding to the zonal and meridional
1147  by setting the logical variable \textbf{implicitViscosity }to '.\texttt{TRUE}%    components of the wind stress, respectively (if you want the stress
1148  .'. In addition, biharmonic mixing can be added as well through the variable    to be along the direction of only one of the model horizontal axes,
1149  \textbf{viscA4}\textit{\ }(in m$^{4}$s$^{-1}$). On a spherical polar grid,    you only need to generate one file). The format of the files is
1150  you might also need to set the variable \textbf{cosPower} which is set to 0    similar to the bathymetry file. The zonal (meridional) stress data
1151  by default and which represents the power of cosine of latitude to multiply    are assumed to be in Pa and located at U-points (V-points). As for
1152  viscosity. Slip or no-slip conditions at lateral and bottom boundaries are    the bathymetry, the precision with which to read the binary data is
1153  specified through the logical variables \textbf{no\_slip\_sides}\textit{\ }%    controlled by the variable \textbf{readBinaryPrec}.  See the matlab
1154  and \textbf{no\_slip\_bottom}. If set to '\texttt{.FALSE.}', free-slip    program \textit{gendata.m} in the \textit{input} directories under
1155  boundary conditions are applied. If no-slip boundary conditions are applied    \textit{verification} to see how simple analytical wind forcing data
1156  at the bottom, a bottom drag can be applied as well. Two forms are    are generated for the case study experiments.
1157  available: linear (set the variable \textbf{bottomDragLinear}\textit{\ }in s$%    
1158  ^{-1}$) and quadratic (set the variable \textbf{bottomDragQuadratic}\textit{%    There is also the possibility of prescribing time-dependent periodic
1159  \ }in m$^{-1}$).    forcing. To do this, concatenate the successive time records into a
1160      single file (for each stress component) ordered in a (x,y,t) fashion
1161  The Fourier and Shapiro filters are described elsewhere.    and set the following variables: \textbf{periodicExternalForcing }to
1162      \texttt{'.TRUE.'}, \textbf{externForcingPeriod }to the period (in s)
1163  \begin{itemize}    of which the forcing varies (typically 1 month), and
1164  \item C-D scheme    \textbf{externForcingCycle} to the repeat time (in s) of the forcing
1165  \end{itemize}    (typically 1 year -- note: \textbf{ externForcingCycle} must be a
1166      multiple of \textbf{externForcingPeriod}).  With these variables set
1167  If you run at a sufficiently coarse resolution, you will need the C-D scheme    up, the model will interpolate the forcing linearly at each
1168  for the computation of the Coriolis terms. The variable\textbf{\ tauCD},    iteration.
1169  which represents the C-D scheme coupling timescale (in s) needs to be set.  
1170    \item[dissipation] \
1171  \begin{itemize}    
1172  \item calculation of pressure/geopotential    The lateral eddy viscosity coefficient is specified through the
1173  \end{itemize}    variable \textbf{viscAh} (in m$^{2}$s$^{-1}$). The vertical eddy
1174      viscosity coefficient is specified through the variable
1175  First, to run a non-hydrostatic ocean simulation, set the logical variable    \textbf{viscAz} (in m$^{2}$s$^{-1}$) for the ocean and
1176  \textbf{nonHydrostatic} to '.\texttt{TRUE}.'. The pressure field is then    \textbf{viscAp} (in Pa$^{2}$s$^{-1}$) for the atmosphere.  The
1177  inverted through a 3D elliptic equation. (Note: this capability is not    vertical diffusive fluxes can be computed implicitly by setting the
1178  available for the atmosphere yet.) By default, a hydrostatic simulation is    logical variable \textbf{implicitViscosity }to \texttt{'.TRUE.'}.
1179  assumed and a 2D elliptic equation is used to invert the pressure field. The    In addition, biharmonic mixing can be added as well through the
1180  parameters controlling the behaviour of the elliptic solvers are the    variable \textbf{viscA4} (in m$^{4}$s$^{-1}$). On a spherical polar
1181  variables \textbf{cg2dMaxIters}\textit{\ }and \textbf{cg2dTargetResidual }%    grid, you might also need to set the variable \textbf{cosPower}
1182  for the 2D case and \textbf{cg3dMaxIters}\textit{\ }and \textbf{%    which is set to 0 by default and which represents the power of
1183  cg3dTargetResidual }for the 3D case. You probably won't need to alter the    cosine of latitude to multiply viscosity. Slip or no-slip conditions
1184  default values (are we sure of this?).    at lateral and bottom boundaries are specified through the logical
1185      variables \textbf{no\_slip\_sides} and \textbf{no\_slip\_bottom}. If
1186  For the calculation of the surface pressure (for the ocean) or surface    set to \texttt{'.FALSE.'}, free-slip boundary conditions are
1187  geopotential (for the atmosphere) you need to set the logical variables    applied. If no-slip boundary conditions are applied at the bottom, a
1188  \textbf{rigidLid} and \textbf{implicitFreeSurface}\textit{\ }(set one to '.%    bottom drag can be applied as well. Two forms are available: linear
1189  \texttt{TRUE}.' and the other to '.\texttt{FALSE}.' depending on how you    (set the variable \textbf{bottomDragLinear} in s$ ^{-1}$) and
1190  want to deal with the ocean upper or atmosphere lower boundary).    quadratic (set the variable \textbf{bottomDragQuadratic} in
1191      m$^{-1}$).
1192  \subsubsection{Tracer equations}  
1193      The Fourier and Shapiro filters are described elsewhere.
1194  This section covers the tracer equations i.e. the potential temperature  
1195  equation and the salinity (for the ocean) or specific humidity (for the  \item[C-D scheme] \
1196  atmosphere) equation. As for the momentum equations, we only describe for    
1197  now the parameters that you are likely to change. The logical variables    If you run at a sufficiently coarse resolution, you will need the
1198  \textbf{tempDiffusion}\textit{, }\textbf{tempAdvection}\textit{, }\textbf{%    C-D scheme for the computation of the Coriolis terms. The
1199  tempForcing}\textit{,} and \textbf{tempStepping} allow you to turn on/off    variable\textbf{\ tauCD}, which represents the C-D scheme coupling
1200  terms in the temperature equation (same thing for salinity or specific    timescale (in s) needs to be set.
1201  humidity with variables \textbf{saltDiffusion}\textit{, }\textbf{%    
1202  saltAdvection}\textit{\ }etc). These variables are all assumed here to be  \item[calculation of pressure/geopotential] \
1203  set to '.\texttt{TRUE}.'. Look at file \textit{model/inc/PARAMS.h }for a    
1204  precise definition.    First, to run a non-hydrostatic ocean simulation, set the logical
1205      variable \textbf{nonHydrostatic} to \texttt{'.TRUE.'}. The pressure
1206  \begin{itemize}    field is then inverted through a 3D elliptic equation. (Note: this
1207  \item initialization    capability is not available for the atmosphere yet.) By default, a
1208  \end{itemize}    hydrostatic simulation is assumed and a 2D elliptic equation is used
1209      to invert the pressure field. The parameters controlling the
1210  The initial tracer data can be contained in the binary files \textbf{%    behaviour of the elliptic solvers are the variables
1211  hydrogThetaFile }and \textbf{hydrogSaltFile}. These files should contain 3D    \textbf{cg2dMaxIters} and \textbf{cg2dTargetResidual } for
1212  data ordered in an (x, y, r) fashion with k=1 as the first vertical level.    the 2D case and \textbf{cg3dMaxIters} and
1213  If no file names are provided, the tracers are then initialized with the    \textbf{cg3dTargetResidual} for the 3D case. You probably won't need to
1214  values of \textbf{tRef }and \textbf{sRef }mentioned above (in the equation    alter the default values (are we sure of this?).
1215  of state section). In this case, the initial tracer data are uniform in x    
1216  and y for each depth level.    For the calculation of the surface pressure (for the ocean) or
1217      surface geopotential (for the atmosphere) you need to set the
1218  \begin{itemize}    logical variables \textbf{rigidLid} and \textbf{implicitFreeSurface}
1219  \item forcing    (set one to \texttt{'.TRUE.'} and the other to \texttt{'.FALSE.'}
1220  \end{itemize}    depending on how you want to deal with the ocean upper or atmosphere
1221      lower boundary).
1222  This part is more relevant for the ocean, the procedure for the atmosphere  
1223  not being completely stabilized at the moment.  \end{description}
1224    
1225  A combination of fluxes data and relaxation terms can be used for driving  \subsection{Tracer equations}
1226  the tracer equations. \ For potential temperature, heat flux data (in W/m$%  
1227  ^{2}$) can be stored in the 2D binary file \textbf{surfQfile}\textit{. }%  This section covers the tracer equations i.e. the potential
1228  Alternatively or in addition, the forcing can be specified through a  temperature equation and the salinity (for the ocean) or specific
1229  relaxation term. The SST data to which the model surface temperatures are  humidity (for the atmosphere) equation. As for the momentum equations,
1230  restored to are supposed to be stored in the 2D binary file \textbf{%  we only describe for now the parameters that you are likely to change.
1231  thetaClimFile}\textit{. }The corresponding relaxation time scale coefficient  The logical variables \textbf{tempDiffusion} \textbf{tempAdvection}
1232  is set through the variable \textbf{tauThetaClimRelax}\textit{\ }(in s). The  \textbf{tempForcing}, and \textbf{tempStepping} allow you to turn
1233  same procedure applies for salinity with the variable names \textbf{EmPmRfile%  on/off terms in the temperature equation (same thing for salinity or
1234  }\textit{, }\textbf{saltClimFile}\textit{, }and \textbf{tauSaltClimRelax}%  specific humidity with variables \textbf{saltDiffusion},
1235  \textit{\ }for freshwater flux (in m/s) and surface salinity (in ppt) data  \textbf{saltAdvection} etc.). These variables are all assumed here to
1236  files and relaxation time scale coefficient (in s), respectively. Also for  be set to \texttt{'.TRUE.'}. Look at file \textit{model/inc/PARAMS.h}
1237  salinity, if the CPP key \textbf{USE\_NATURAL\_BCS} is turned on, natural  for a precise definition.
1238  boundary conditions are applied i.e. when computing the surface salinity  
1239  tendency, the freshwater flux is multiplied by the model surface salinity  \begin{description}
1240  instead of a constant salinity value.  \item[initialization] \
1241      
1242  As for the other input files, the precision with which to read the data is    The initial tracer data can be contained in the binary files
1243  controlled by the variable \textbf{readBinaryPrec}. Time-dependent, periodic    \textbf{hydrogThetaFile} and \textbf{hydrogSaltFile}. These files
1244  forcing can be applied as well following the same procedure used for the    should contain 3D data ordered in an (x,y,r) fashion with k=1 as the
1245  wind forcing data (see above).    first vertical level.  If no file names are provided, the tracers
1246      are then initialized with the values of \textbf{tRef} and
1247  \begin{itemize}    \textbf{sRef} mentioned above (in the equation of state section). In
1248  \item dissipation    this case, the initial tracer data are uniform in x and y for each
1249  \end{itemize}    depth level.
1250    
1251  Lateral eddy diffusivities for temperature and salinity/specific humidity  \item[forcing] \
1252  are specified through the variables \textbf{diffKhT }and \textbf{diffKhS }%    
1253  (in m$^{2}$/s). Vertical eddy diffusivities are specified through the    This part is more relevant for the ocean, the procedure for the
1254  variables \textbf{diffKzT }and \textbf{diffKzS }(in m$^{2}$/s) for the ocean    atmosphere not being completely stabilized at the moment.
1255  and \textbf{diffKpT }and \textbf{diffKpS }(in Pa$^{2}$/s) for the    
1256  atmosphere. The vertical diffusive fluxes can be computed implicitly by    A combination of fluxes data and relaxation terms can be used for
1257  setting the logical variable \textbf{implicitDiffusion }to '.\texttt{TRUE}%    driving the tracer equations.  For potential temperature, heat flux
1258  .'. In addition, biharmonic diffusivities can be specified as well through    data (in W/m$ ^{2}$) can be stored in the 2D binary file
1259  the coefficients \textbf{diffK4T }and \textbf{diffK4S }(in m$^{4}$/s). Note    \textbf{surfQfile}.  Alternatively or in addition, the forcing can
1260  that the cosine power scaling (specified through \textbf{cosPower }- see the    be specified through a relaxation term. The SST data to which the
1261  momentum equations section) is applied to the tracer diffusivities    model surface temperatures are restored to are supposed to be stored
1262  (Laplacian and biharmonic) as well. The Gent and McWilliams parameterization    in the 2D binary file \textbf{thetaClimFile}. The corresponding
1263  for oceanic tracers is described in the package section. Finally, note that    relaxation time scale coefficient is set through the variable
1264  tracers can be also subject to Fourier and Shapiro filtering (see the    \textbf{tauThetaClimRelax} (in s). The same procedure applies for
1265  corresponding section on these filters).    salinity with the variable names \textbf{EmPmRfile},
1266      \textbf{saltClimFile}, and \textbf{tauSaltClimRelax} for freshwater
1267  \begin{itemize}    flux (in m/s) and surface salinity (in ppt) data files and
1268  \item ocean convection    relaxation time scale coefficient (in s), respectively. Also for
1269  \end{itemize}    salinity, if the CPP key \textbf{USE\_NATURAL\_BCS} is turned on,
1270      natural boundary conditions are applied i.e. when computing the
1271  Two options are available to parameterize ocean convection: one is to use    surface salinity tendency, the freshwater flux is multiplied by the
1272  the convective adjustment scheme. In this case, you need to set the variable    model surface salinity instead of a constant salinity value.
1273  \textbf{cadjFreq}, which represents the frequency (in s) with which the    
1274  adjustment algorithm is called, to a non-zero value (if set to a negative    As for the other input files, the precision with which to read the
1275  value by the user, the model will set it to the tracer time step). The other    data is controlled by the variable \textbf{readBinaryPrec}.
1276  option is to parameterize convection with implicit vertical diffusion. To do    Time-dependent, periodic forcing can be applied as well following
1277  this, set the logical variable \textbf{implicitDiffusion }to '.\texttt{TRUE}%    the same procedure used for the wind forcing data (see above).
1278  .' and the real variable \textbf{ivdc\_kappa }to a value (in m$^{2}$/s) you  
1279  wish the tracer vertical diffusivities to have when mixing tracers  \item[dissipation] \
1280  vertically due to static instabilities. Note that \textbf{cadjFreq }and    
1281  \textbf{ivdc\_kappa }can not both have non-zero value.    Lateral eddy diffusivities for temperature and salinity/specific
1282      humidity are specified through the variables \textbf{diffKhT} and
1283  \subsubsection{Simulation controls}    \textbf{diffKhS} (in m$^{2}$/s). Vertical eddy diffusivities are
1284      specified through the variables \textbf{diffKzT} and
1285  The model ''clock'' is defined by the variable \textbf{deltaTClock }(in s)    \textbf{diffKzS} (in m$^{2}$/s) for the ocean and \textbf{diffKpT
1286  which determines the IO frequencies and is used in tagging output.    }and \textbf{diffKpS} (in Pa$^{2}$/s) for the atmosphere. The
1287  Typically, you will set it to the tracer time step for accelerated runs    vertical diffusive fluxes can be computed implicitly by setting the
1288  (otherwise it is simply set to the default time step \textbf{deltaT}).    logical variable \textbf{implicitDiffusion} to \texttt{'.TRUE.'}.
1289  Frequency of checkpointing and dumping of the model state are referenced to    In addition, biharmonic diffusivities can be specified as well
1290  this clock (see below).    through the coefficients \textbf{diffK4T} and \textbf{diffK4S} (in
1291      m$^{4}$/s). Note that the cosine power scaling (specified through
1292  \begin{itemize}    \textbf{cosPower}---see the momentum equations section) is applied to
1293  \item run duration    the tracer diffusivities (Laplacian and biharmonic) as well. The
1294  \end{itemize}    Gent and McWilliams parameterization for oceanic tracers is
1295      described in the package section. Finally, note that tracers can be
1296  The beginning of a simulation is set by specifying a start time (in s)    also subject to Fourier and Shapiro filtering (see the corresponding
1297  through the real variable \textbf{startTime }or by specifying an initial    section on these filters).
1298  iteration number through the integer variable \textbf{nIter0}. If these  
1299  variables are set to nonzero values, the model will look for a ''pickup''  \item[ocean convection] \
1300  file \textit{pickup.0000nIter0 }to restart the integration\textit{. }The end    
1301  of a simulation is set through the real variable \textbf{endTime }(in s).    Two options are available to parameterize ocean convection: one is
1302  Alternatively, you can specify instead the number of time steps to execute    to use the convective adjustment scheme. In this case, you need to
1303  through the integer variable \textbf{nTimeSteps}.    set the variable \textbf{cadjFreq}, which represents the frequency
1304      (in s) with which the adjustment algorithm is called, to a non-zero
1305  \begin{itemize}    value (if set to a negative value by the user, the model will set it
1306  \item frequency of output    to the tracer time step). The other option is to parameterize
1307  \end{itemize}    convection with implicit vertical diffusion. To do this, set the
1308      logical variable \textbf{implicitDiffusion} to \texttt{'.TRUE.'}
1309  Real variables defining frequencies (in s) with which output files are    and the real variable \textbf{ivdc\_kappa} to a value (in m$^{2}$/s)
1310  written on disk need to be set up. \textbf{dumpFreq }controls the frequency    you wish the tracer vertical diffusivities to have when mixing
1311  with which the instantaneous state of the model is saved. \textbf{chkPtFreq }%    tracers vertically due to static instabilities. Note that
1312  and \textbf{pchkPtFreq }control the output frequency of rolling and    \textbf{cadjFreq} and \textbf{ivdc\_kappa}can not both have non-zero
1313  permanent checkpoint files, respectively. See section 1.5.1 Output files for the    value.
1314  definition of model state and checkpoint files. In addition, time-averaged  
1315  fields can be written out by setting the variable \textbf{taveFreq} (in s).  \end{description}
1316  The precision with which to write the binary data is controlled by the  
1317  integer variable w\textbf{riteBinaryPrec }(set it to \texttt{32} or \texttt{%  \subsection{Simulation controls}
1318  64}).  
1319    The model ''clock'' is defined by the variable \textbf{deltaTClock}
1320    (in s) which determines the IO frequencies and is used in tagging
1321    output.  Typically, you will set it to the tracer time step for
1322    accelerated runs (otherwise it is simply set to the default time step
1323    \textbf{deltaT}).  Frequency of checkpointing and dumping of the model
1324    state are referenced to this clock (see below).
1325    
1326    \begin{description}
1327    \item[run duration] \
1328      
1329      The beginning of a simulation is set by specifying a start time (in
1330      s) through the real variable \textbf{startTime} or by specifying an
1331      initial iteration number through the integer variable
1332      \textbf{nIter0}. If these variables are set to nonzero values, the
1333      model will look for a ''pickup'' file \textit{pickup.0000nIter0} to
1334      restart the integration. The end of a simulation is set through the
1335      real variable \textbf{endTime} (in s).  Alternatively, you can
1336      specify instead the number of time steps to execute through the
1337      integer variable \textbf{nTimeSteps}.
1338    
1339    \item[frequency of output] \
1340      
1341      Real variables defining frequencies (in s) with which output files
1342      are written on disk need to be set up. \textbf{dumpFreq} controls
1343      the frequency with which the instantaneous state of the model is
1344      saved. \textbf{chkPtFreq} and \textbf{pchkPtFreq} control the output
1345      frequency of rolling and permanent checkpoint files, respectively.
1346      See section 1.5.1 Output files for the definition of model state and
1347      checkpoint files. In addition, time-averaged fields can be written
1348      out by setting the variable \textbf{taveFreq} (in s).  The precision
1349      with which to write the binary data is controlled by the integer
1350      variable w\textbf{riteBinaryPrec} (set it to \texttt{32} or
1351      \texttt{64}).
1352    
1353    \end{description}
1354    
1355    
1356    %%% Local Variables:
1357    %%% mode: latex
1358    %%% TeX-master: t
1359    %%% End:

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