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1  % $Header$  % $Header$
2  % $Name$  % $Name$
3    
4  \section{Getting started}  %\section{Getting started}
5    
6  In this part, we describe how to use the model. In the first section, we  In this section, we describe how to use the model. In the first
7  provide enough information to help you get started with the model. We  section, we provide enough information to help you get started with
8  believe the best way to familiarize yourself with the model is to run the  the model. We believe the best way to familiarize yourself with the
9  case study examples provided with the base version. Information on how to  model is to run the case study examples provided with the base
10  obtain, compile, and run the code is found there as well as a brief  version. Information on how to obtain, compile, and run the code is
11  description of the model structure directory and the case study examples.  found there as well as a brief description of the model structure
12  The latter and the code structure are described more fully in sections 2 and  directory and the case study examples.  The latter and the code
13  3, respectively. In section 4, we provide information on how to customize  structure are described more fully in chapters
14  the code when you are ready to try implementing the configuration you have  \ref{chap:discretization} and \ref{chap:sarch}, respectively. Here, in
15  in mind.  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  \subsection{Obtaining the code}  \section{Where to find information}
19    \label{sect:whereToFindInfo}
20    
21  The reference web site for the model is:  A web site is maintained for release 2 (``Pelican'') of MITgcm:
22    \begin{rawhtml} <A href=http://mitgcm.org/pelican/ target="idontexist"> \end{rawhtml}
23  \begin{verbatim}  \begin{verbatim}
24  http://mitgcm.org  http://mitgcm.org/pelican
25  \end{verbatim}  \end{verbatim}
26    \begin{rawhtml} </A> \end{rawhtml}
27  On this site, you can download the model as well as find useful information,  Here you will find an on-line version of this document, a
28  some of which might overlap with what is written here. There is also a  ``browsable'' copy of the code and a searchable database of the model
29  support news group for the model located at (send your message to \texttt{%  and site, as well as links for downloading the model and
30  support@mitgcm.org}):  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}  \begin{verbatim}
44  news://mitgcm.org/mitgcm.support  http://mitgcm.org/htdig/
45  \end{verbatim}  \end{verbatim}
46    \begin{rawhtml} </A> \end{rawhtml}
47    %%% http://www.google.com/search?q=hydrostatic+site%3Amitgcm.org
48    
49    
50    
51    \section{Obtaining the code}
52    \label{sect:obtainingCode}
53    
54    MITgcm can be downloaded from our system by following
55    the instructions below. As a courtesy we ask that you send e-mail to us at
56    \begin{rawhtml} <A href=mailto:MITgcm-support@mitgcm.org> \end{rawhtml}
57    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    \end{enumerate}
81    
82    \subsubsection{Checkout from CVS}
83    \label{sect:cvs_checkout}
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 source for the release:  To obtain the latest sources type:
110  \begin{verbatim}  \begin{verbatim}
111  % cvs co -d directory -P -r release1 MITgcmUV  % cvs co MITgcm
112  \end{verbatim}  \end{verbatim}
113    or to get a specific release type:
 This creates a directory called \textit{directory}. If \textit{directory}  
 exists this command updates your code based on the repository. Each  
 directory in the source tree contains a directory \textit{CVS}. This  
 information is required by CVS to keep track of your file versions with  
 respect to the repository. Don't edit the files in \textit{CVS}! To obtain a  
 different \textit{version} that is not the latest source:  
114  \begin{verbatim}  \begin{verbatim}
115  % cvs co -d directory -P -r version MITgcm  % cvs co -P -r checkpoint52i_post  MITgcm
116  \end{verbatim}  \end{verbatim}
117  or the latest development version:  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}  \begin{verbatim}
123  % cvs co -d directory -P MITgcm  http://mitgcm.org/source_code.html
124  \end{verbatim}  \end{verbatim}
125    \begin{rawhtml} </A> \end{rawhtml}
126    
127  \subsubsection{other methods}  As a convenience, the MITgcm CVS server contains aliases which are
128    named subsets of the codebase.  These aliases can be especially
129  You can download the model as a tar file from the reference web site at:  helpful when used over slow internet connections or on machines with
130    restricted storage space.  Table \ref{tab:cvsModules} contains a list
131    of CVS aliases
132    \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  http://mitgcm.org/download/     %  cvs co MITgcm_verif_basic
168       %  mv MITgcm MITgcm_verif_basic
169  \end{verbatim}  \end{verbatim}
170    
 \subsection{Model and directory structure}  
171    
172  The ``numerical'' model is contained within a execution environment support  \subsubsection{Conventional download method}
173  wrapper. This wrapper is designed to provide a general framework for  \label{sect:conventionalDownload}
174  grid-point models. MITgcmUV is a specific numerical model that uses the  
175  framework. Under this structure the model is split into execution  If you do not have CVS on your system, you can download the model as a
176  environment support code and conventional numerical model code. The  tar file from the web site at:
177  execution environment support code is held under the \textit{eesupp}  \begin{rawhtml} <A href=http://mitgcm.org/download target="idontexist"> \end{rawhtml}
178  directory. The grid point model code is held under the \textit{model}  \begin{verbatim}
179  directory. Code execution actually starts in the \textit{eesupp} routines  http://mitgcm.org/download/
180  and not in the \textit{model} routines. For this reason the top-level  \end{verbatim}
181  \textit{MAIN.F} is in the \textit{eesupp/src} directory. In general,  \begin{rawhtml} </A> \end{rawhtml}
182  end-users should not need to worry about this level. The top-level routine  The tar file still contains CVS information which we urge you not to
183  for the numerical part of the code is in \textit{model/src/THE\_MODEL\_MAIN.F%  delete; even if you do not use CVS yourself the information can help
184  }. Here is a brief description of the directory structure of the model under  us if you should need to send us your copy of the code.  If a recent
185  the root tree (a detailed description is given in section 3: Code structure).  tar file does not exist, then please contact the developers through
186    the
187    \begin{rawhtml} <A href=''mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
188    MITgcm-support@mitgcm.org
189    \begin{rawhtml} </A> \end{rawhtml}
190    mailing list.
191    
192    \subsubsection{Upgrading from an earlier version}
193    
194    If you already have an earlier version of the code you can ``upgrade''
195    your copy instead of downloading the entire repository again. First,
196    ``cd'' (change directory) to the top of your working copy:
197    \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      Global configuration, on latitude longitude grid with 128x64x5 grid
393      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{aim.5l\_LatLon} - Intermediate Atmospheric physics, 5 layers  \end{enumerate}
 Molteni physics package. Global configuration, 128x64x5 resolution.  
429    
430  \item \textit{adjustment.128x64x1}  \subsection{Directory structure of model examples}
   
 \item \textit{adjustment.cs-32x32x1}  
 \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:
437    
438  \begin{itemize}    \begin{itemize}
439  \item \textit{code/CPP\_EEOPTIONS.h}: declares CPP keys relative to the    \item \textit{code/CPP\_EEOPTIONS.h}: declares CPP keys relative to
440  ``execution environment'' part of the code. The default version is located      the ``execution environment'' part of the code. The default
441  in \textit{eesupp/inc}.      version is located in \textit{eesupp/inc}.
442      
443  \item \textit{code/CPP\_OPTIONS.h}: declares CPP keys relative to the    \item \textit{code/CPP\_OPTIONS.h}: declares CPP keys relative to
444  ``numerical model'' part of the code. The default version is located in      the ``numerical model'' part of the code. The default version is
445  \textit{model/inc}.      located in \textit{model/inc}.
446      
447  \item \textit{code/SIZE.h}: declares size of underlying computational grid.    \item \textit{code/SIZE.h}: declares size of underlying
448  The default version is located in \textit{model/inc}.      computational grid.  The default version is located in
449  \end{itemize}      \textit{model/inc}.
450      \end{itemize}
451  In addition, other include files and subroutines might be present in \textit{%    
452  code} depending on the particular experiment. See section 2 for more details.    In addition, other include files and subroutines might be present in
453      \textit{code} depending on the particular experiment. See Section 2
454  \item \textit{input}: contains the input data files required to run the    for more details.
455  example. At a mimimum, the \textit{input} directory contains the following    
456  files:  \item \textit{input}: contains the input data files required to run
457      the example. At a minimum, the \textit{input} directory contains the
458  \begin{itemize}    following files:
459  \item \textit{input/data}: this file, written as a namelist, specifies the  
460  main parameters for the experiment.    \begin{itemize}
461      \item \textit{input/data}: this file, written as a namelist,
462  \item \textit{input/data.pkg}: contains parameters relative to the packages      specifies the main parameters for the experiment.
463  used in the experiment.    
464      \item \textit{input/data.pkg}: contains parameters relative to the
465  \item \textit{input/eedata}: this file contains ``execution environment''      packages used in the experiment.
466  data. At present, this consists of a specification of the number of threads    
467  to use in $X$ and $Y$ under multithreaded execution.    \item \textit{input/eedata}: this file contains ``execution
468  \end{itemize}      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  In addition, you will also find in this directory the forcing and topography  On many systems, the {\em genmake2} program will be able to
513  files as well as the files describing the initial state of the experiment.  automatically recognize the hardware, find compilers and other tools
514  This varies from experiment to experiment. See section 2 for more details.  within the user's path (``echo \$PATH''), and then choose an
515    appropriate set of options from the files contained in the {\em
516  \item \textit{results}: this directory contains the output file \textit{%    tools/build\_options} directory.  Under some circumstances, a user
517  output.txt} produced by the simulation example. This file is useful for  may have to create a new ``optfile'' in order to specify the exact
518  comparison with your own output when you run the experiment.  combination of compiler, compiler flags, libraries, and other options
519  \end{itemize}  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  Once you have chosen the example you want to run, you are ready to compile  To specify an optfile to {\em genmake2}, the syntax is:
533  the code.  \begin{verbatim}
534    % ../../../tools/genmake2 -mods=../code -of /path/to/optfile
535    \end{verbatim}
536    
537  \subsection{Compiling the code}  Once a {\em Makefile} has been generated, we create the dependencies:
538    \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  \subsubsection{The script \textit{genmake}}  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  To compile the code, use the script \textit{genmake} located in the \textit{%  Now you are ready to run the model. General instructions for doing so are
556  tools} directory. \textit{genmake} is a script that generates the makefile.  given in section \ref{sect:runModel}. Here, we can run the model with:
557  It has been written so that the code can be compiled on a wide diversity of  \begin{verbatim}
558  machines and systems. However, if it doesn't work the first time on your  ./mitgcmuv > output.txt
559  platform, you might need to edit certain lines of \textit{genmake} in the  \end{verbatim}
560  section containing the setups for the different machines. The file is  where we are re-directing the stream of text output to the file {\em
561  structured like this:  output.txt}.
 \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:  
562    
 \begin{itemize}  
 \item -rootdir=dir  
563    
564  indicates where the model root directory is relative to the directory where  \subsection{Building/compiling the code elsewhere}
 you are compiling. This option is not needed if you compile in the \textit{%  
 bin} directory (which is the default compilation directory) or within the  
 \textit{verification} tree.  
565    
566  \item -mods=dir1,dir2,...  In the example above (section \ref{sect:buildingCode}) we built the
567    executable in the {\em input} directory of the experiment for
568    convenience. You can also configure and compile the code in other
569    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  indicates the relative or absolute paths directories where the sources  The following sections outline some possible methods of organizing
575  should take precedence over the default versions (located in \textit{model},  your source and data.
 \textit{eesupp},...). Typically, this option is used when running the  
 examples, see below.  
576    
577  \item -enable=pkg1,pkg2,...  \subsubsection{Building from the {\em ../code directory}}
578    
579  enables packages source code \textit{pkg1}, \textit{pkg2},... when creating  This is just as simple as building in the {\em input/} directory:
580  the makefile.  \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  \item -disable=pkg1,pkg2,...  \subsubsection{Building from a new directory}
603    
604  disables packages source code \textit{pkg1}, \textit{pkg2},... when creating  Since the {\em input} directory contains input files it is often more
605  the makefile.  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  \item -platform=machine  \subsubsection{Building on a scratch disk}
634    
635  specifies the platform for which you want the makefile. In general, you  Model object files and output data can use up large amounts of disk
636  won't need this option. \textit{genmake} will select the right machine for  space so it is often the case that you will be operating on a large
637  you (the one you're working on!). However, this option is useful if you have  scratch disk. Assuming the model source is in {\em ~/MITgcm} then the
638  a choice of several compilers on one machine and you want to use the one  following commands will build the model in {\em /scratch/exp2-run1}:
639  that is not the default (ex: \texttt{pgf77} instead of \texttt{f77} under  \begin{verbatim}
640  Linux).  % 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  \item -mpi  As before, you could build in one directory and make multiple runs of
653    the one experiment:
654    \begin{verbatim}
655    % cd /scratch/exp2
656    % mkdir build
657    % 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    
 this is used when you want to run the model in parallel processing mode  
 under mpi (see section on parallel computation for more details).  
668    
669  \item -jam  \subsection{Using \texttt{genmake2}}
670    \label{sect:genmake}
671    
672  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
673  under jam (see section on parallel computation for more details).  in the \texttt{tools} directory) to generate a Makefile.
674  \end{itemize}  \texttt{genmake2} is a shell script written to work with all
675    ``sh''--compatible shells including bash v1, bash v2, and Bourne.
676    Internally, \texttt{genmake2} determines the locations of needed
677    files, the compiler, compiler options, libraries, and Unix tools.  It
678    relies upon a number of ``optfiles'' located in the
679    \texttt{tools/build\_options} directory.
680    
681    The purpose of the optfiles is to provide all the compilation options
682    for particular ``platforms'' (where ``platform'' roughly means the
683    combination of the hardware and the compiler) and code configurations.
684    Given the combinations of possible compilers and library dependencies
685    ({\it eg.}  MPI and NetCDF) there may be numerous optfiles available
686    for a single machine.  The naming scheme for the majority of the
687    optfiles shipped with the code is
688    \begin{center}
689      {\bf OS\_HARDWARE\_COMPILER }
690    \end{center}
691    where
692    \begin{description}
693    \item[OS] is the name of the operating system (generally the
694      lower-case output of the {\tt 'uname'} command)
695    \item[HARDWARE] is a string that describes the CPU type and
696      corresponds to output from the  {\tt 'uname -m'} command:
697      \begin{description}
698      \item[ia32] is for ``x86'' machines such as i386, i486, i586, i686,
699        and athlon
700      \item[ia64] is for Intel IA64 systems (eg. Itanium, Itanium2)
701      \item[amd64] is AMD x86\_64 systems
702      \item[ppc] is for Mac PowerPC systems
703      \end{description}
704    \item[COMPILER] is the compiler name (generally, the name of the
705      FORTRAN executable)
706    \end{description}
707    
708    In many cases, the default optfiles are sufficient and will result in
709    usable Makefiles.  However, for some machines or code configurations,
710    new ``optfiles'' must be written. To create a new optfile, it is
711    generally best to start with one of the defaults and modify it to suit
712    your needs.  Like \texttt{genmake2}, the optfiles are all written
713    using a simple ``sh''--compatible syntax.  While nearly all variables
714    used within \texttt{genmake2} may be specified in the optfiles, the
715    critical ones that should be defined are:
716    
717    \begin{description}
718    \item[FC] the FORTRAN compiler (executable) to use
719    \item[DEFINES] the command-line DEFINE options passed to the compiler
720    \item[CPP] the C pre-processor to use
721    \item[NOOPTFLAGS] options flags for special files that should not be
722      optimized
723    \end{description}
724    
725  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''
726  \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:  
727  \begin{verbatim}  \begin{verbatim}
728  % cd verification/exp2/input  FC=g77
729  % ../../../tools/genmake  DEFINES='-D_BYTESWAPIO -DWORDLENGTH=4'
730  % make depend  CPP='cpp  -traditional -P'
731  % make  NOOPTFLAGS='-O0'
732    #  For IEEE, use the "-ffloat-store" option
733    if test "x$IEEE" = x ; then
734        FFLAGS='-Wimplicit -Wunused -Wuninitialized'
735        FOPTIM='-O3 -malign-double -funroll-loops'
736    else
737        FFLAGS='-Wimplicit -Wunused -ffloat-store'
738        FOPTIM='-O0 -malign-double'
739    fi
740  \end{verbatim}  \end{verbatim}
741    
742  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
743  to use the following options when invoking \textit{genmake}:  are strongly encouraged to submit the optfile to the MITgcm project
744    for inclusion.  Please send the file to the
745    \begin{rawhtml} <A href="mail-to:MITgcm-support@mitgcm.org"> \end{rawhtml}
746    \begin{center}
747      MITgcm-support@mitgcm.org
748    \end{center}
749    \begin{rawhtml} </A> \end{rawhtml}
750    mailing list.
751    
752    In addition to the optfiles, \texttt{genmake2} supports a number of
753    helpful command-line options.  A complete list of these options can be
754    obtained from:
755  \begin{verbatim}  \begin{verbatim}
756  % ../../../tools/genmake  -mods=../code  % genmake2 -h
757  \end{verbatim}  \end{verbatim}
758    
759  In addition, you will probably want to disable some of the packages. Taking  The most important command-line options are:
760  again the case of \textit{exp2}, the full \textit{genmake} command will  \begin{description}
761  probably look like this:    
762    \item[\texttt{--optfile=/PATH/FILENAME}] specifies the optfile that
763      should be used for a particular build.
764      
765      If no "optfile" is specified (either through the command line or the
766      MITGCM\_OPTFILE environment variable), genmake2 will try to make a
767      reasonable guess from the list provided in {\em
768        tools/build\_options}.  The method used for making this guess is
769      to first determine the combination of operating system and hardware
770      (eg. "linux\_ia32") and then find a working FORTRAN compiler within
771      the user's path.  When these three items have been identified,
772      genmake2 will try to find an optfile that has a matching name.
773      
774    \item[\texttt{--pdefault='PKG1 PKG2 PKG3 ...'}] specifies the default
775      set of packages to be used.  The normal order of precedence for
776      packages is as follows:
777      \begin{enumerate}
778      \item If available, the command line (\texttt{--pdefault}) settings
779        over-rule any others.
780    
781      \item Next, \texttt{genmake2} will look for a file named
782        ``\texttt{packages.conf}'' in the local directory or in any of the
783        directories specified with the \texttt{--mods} option.
784        
785      \item Finally, if neither of the above are available,
786        \texttt{genmake2} will use the \texttt{/pkg/pkg\_default} file.
787      \end{enumerate}
788      
789    \item[\texttt{--pdepend=/PATH/FILENAME}] specifies the dependency file
790      used for packages.
791      
792      If not specified, the default dependency file {\em pkg/pkg\_depend}
793      is used.  The syntax for this file is parsed on a line-by-line basis
794      where each line containes either a comment ("\#") or a simple
795      "PKGNAME1 (+|-)PKGNAME2" pairwise rule where the "+" or "-" symbol
796      specifies a "must be used with" or a "must not be used with"
797      relationship, respectively.  If no rule is specified, then it is
798      assumed that the two packages are compatible and will function
799      either with or without each other.
800      
801    \item[\texttt{--adof=/path/to/file}] specifies the "adjoint" or
802      automatic differentiation options file to be used.  The file is
803      analogous to the ``optfile'' defined above but it specifies
804      information for the AD build process.
805      
806      The default file is located in {\em
807        tools/adjoint\_options/adjoint\_default} and it defines the "TAF"
808      and "TAMC" compilers.  An alternate version is also available at
809      {\em tools/adjoint\_options/adjoint\_staf} that selects the newer
810      "STAF" compiler.  As with any compilers, it is helpful to have their
811      directories listed in your {\tt \$PATH} environment variable.
812      
813    \item[\texttt{--mods='DIR1 DIR2 DIR3 ...'}] specifies a list of
814      directories containing ``modifications''.  These directories contain
815      files with names that may (or may not) exist in the main MITgcm
816      source tree but will be overridden by any identically-named sources
817      within the ``MODS'' directories.
818      
819      The order of precedence for this "name-hiding" is as follows:
820      \begin{itemize}
821      \item ``MODS'' directories (in the order given)
822      \item Packages either explicitly specified or provided by default
823        (in the order given)
824      \item Packages included due to package dependencies (in the order
825        that that package dependencies are parsed)
826      \item The "standard dirs" (which may have been specified by the
827        ``-standarddirs'' option)
828      \end{itemize}
829      
830    \item[\texttt{--mpi}] This option enables certain MPI features (using
831      CPP \texttt{\#define}s) within the code and is necessary for MPI
832      builds (see Section \ref{sect:mpi-build}).
833      
834    \item[\texttt{--make=/path/to/gmake}] Due to the poor handling of
835      soft-links and other bugs common with the \texttt{make} versions
836      provided by commercial Unix vendors, GNU \texttt{make} (sometimes
837      called \texttt{gmake}) should be preferred.  This option provides a
838      means for specifying the make executable to be used.
839      
840    \item[\texttt{--bash=/path/to/sh}] On some (usually older UNIX)
841      machines, the ``bash'' shell is unavailable.  To run on these
842      systems, \texttt{genmake2} can be invoked using an ``sh'' (that is,
843      a Bourne, POSIX, or compatible) shell.  The syntax in these
844      circumstances is:
845      \begin{center}
846        \texttt{\%  /bin/sh genmake2 -bash=/bin/sh [...options...]}
847      \end{center}
848      where \texttt{/bin/sh} can be replaced with the full path and name
849      of the desired shell.
850    
851    \end{description}
852    
853    
854    \subsection{Building with MPI}
855    \label{sect:mpi-build}
856    
857    Building MITgcm to use MPI libraries can be complicated due to the
858    variety of different MPI implementations available, their dependencies
859    or interactions with different compilers, and their often ad-hoc
860    locations within file systems.  For these reasons, its generally a
861    good idea to start by finding and reading the documentation for your
862    machine(s) and, if necessary, seeking help from your local systems
863    administrator.
864    
865    The steps for building MITgcm with MPI support are:
866    \begin{enumerate}
867      
868    \item Determine the locations of your MPI-enabled compiler and/or MPI
869      libraries and put them into an options file as described in Section
870      \ref{sect:genmake}.  One can start with one of the examples in:
871      \begin{rawhtml} <A
872        href="http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm/tools/build_options/">
873      \end{rawhtml}
874      \begin{center}
875        \texttt{MITgcm/tools/build\_options/}
876      \end{center}
877      \begin{rawhtml} </A> \end{rawhtml}
878      such as \texttt{linux\_ia32\_g77+mpi\_cg01} or
879      \texttt{linux\_ia64\_efc+mpi} and then edit it to suit the machine at
880      hand.  You may need help from your user guide or local systems
881      administrator to determine the exact location of the MPI libraries.
882      If libraries are not installed, MPI implementations and related
883      tools are available including:
884      \begin{itemize}
885      \item \begin{rawhtml} <A
886          href="http://www-unix.mcs.anl.gov/mpi/mpich/">
887        \end{rawhtml}
888        MPICH
889        \begin{rawhtml} </A> \end{rawhtml}
890    
891      \item \begin{rawhtml} <A
892          href="http://www.lam-mpi.org/">
893        \end{rawhtml}
894        LAM/MPI
895        \begin{rawhtml} </A> \end{rawhtml}
896    
897      \item \begin{rawhtml} <A
898          href="http://www.osc.edu/~pw/mpiexec/">
899        \end{rawhtml}
900        MPIexec
901        \begin{rawhtml} </A> \end{rawhtml}
902      \end{itemize}
903      
904    \item Build the code with the \texttt{genmake2} \texttt{-mpi} option
905      (see Section \ref{sect:genmake}) using commands such as:
906    {\footnotesize \begin{verbatim}
907      %  ../../../tools/genmake2 -mods=../code -mpi -of=YOUR_OPTFILE
908      %  make depend
909      %  make
910    \end{verbatim} }
911      
912    \item Run the code with the appropriate MPI ``run'' or ``exec''
913      program provided with your particular implementation of MPI.
914      Typical MPI packages such as MPICH will use something like:
915  \begin{verbatim}  \begin{verbatim}
916  % ../../../tools/genmake  -mods=../code  -disable=kpp,gmredi,aim,...    %  mpirun -np 4 -machinefile mf ./mitgcmuv
917  \end{verbatim}  \end{verbatim}
918      Sightly more complicated scripts may be needed for many machines
919      since execution of the code may be controlled by both the MPI
920      library and a job scheduling and queueing system such as PBS,
921      LoadLeveller, Condor, or any of a number of similar tools.  A few
922      example scripts (those used for our \begin{rawhtml} <A
923        href="http://mitgcm.org/testing.html"> \end{rawhtml}regular
924      verification runs\begin{rawhtml} </A> \end{rawhtml}) are available
925      at:
926      \begin{rawhtml} <A
927        href="http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm_contrib/test_scripts/">
928      \end{rawhtml}
929      {\footnotesize \tt
930        http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm\_contrib/test\_scripts/ }
931      \begin{rawhtml} </A> \end{rawhtml}
932    
933    \end{enumerate}
934    
935    
936    
937  The make command creates an executable called \textit{mitgcmuv}.  \section{Running the model}
938    \label{sect:runModel}
939    
940    If compilation finished succesfuully (section \ref{sect:buildingCode})
941    then an executable called \texttt{mitgcmuv} will now exist in the
942    local directory.
943    
944  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
945  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}:  
946  \begin{verbatim}  \begin{verbatim}
947  % cd verification/exp2/code  % ./mitgcmuv
 % ../../../tools/genmake  
 % make depend  
 % make  
948  \end{verbatim}  \end{verbatim}
949    The ``./'' is a safe-guard to make sure you use the local executable
950    in case you have others that exist in your path (surely odd if you
951    do!). The above command will spew out many lines of text output to
952    your screen.  This output contains details such as parameter values as
953    well as diagnostics such as mean Kinetic energy, largest CFL number,
954    etc. It is worth keeping this text output with the binary output so we
955    normally re-direct the {\em stdout} stream as follows:
956    \begin{verbatim}
957    % ./mitgcmuv > output.txt
958    \end{verbatim}
959    
960    For the example experiments in {\em verification}, an example of the
961    output is kept in {\em results/output.txt} for comparison. You can compare
962    your {\em output.txt} with this one to check that the set-up works.
963    
 \subsection{Running the model}  
964    
 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.  
965    
966  \subsubsection{Output files}  \subsection{Output files}
967    
968  The model produces various output files. At a minimum, the instantaneous  The model produces various output files. At a minimum, the instantaneous
969  ``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 445  as the pickup files but are named differ Line 1014  as the pickup files but are named differ
1014  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
1015  output to save disk space during long integrations.  output to save disk space during long integrations.
1016    
1017  \subsubsection{Looking at the output}  \subsection{Looking at the output}
1018    
1019  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.
1020  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 459  written in this format. The matlab scrip Line 1028  written in this format. The matlab scrip
1028  \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
1029  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.
1030    
1031  \section{Code structure}  Some examples of reading and visualizing some output in {\em Matlab}:
1032    \begin{verbatim}
1033    % matlab
1034    >> H=rdmds('Depth');
1035    >> contourf(H');colorbar;
1036    >> title('Depth of fluid as used by model');
1037    
1038    >> eta=rdmds('Eta',10);
1039    >> imagesc(eta');axis ij;colorbar;
1040    >> title('Surface height at iter=10');
1041    
1042  \section{Doing it yourself: customizing the code}  >> eta=rdmds('Eta',[0:10:100]);
1043    >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end
1044    \end{verbatim}
1045    
1046  \subsection{\protect\bigskip Configuration and setup}  \section{Doing it yourself: customizing the code}
1047    
1048  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
1049  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
1050  (described previously) that is the closest to your configuration. Then, the  experiment (described previously) that is the closest to your
1051  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
1052  relative to the ''numerical model'' part of the code (the setup relative to  section, we focus on the setup relative to the ``numerical model''
1053  the ''execution environment'' part is covered in the parallel implementation  part of the code (the setup relative to the ``execution environment''
1054  section) and on the variables and parameters that you are likely to change.  part is covered in the parallel implementation section) and on the
1055    variables and parameters that you are likely to change.
1056  The CPP keys relative to the ''numerical model'' part of the code are all  
1057  defined and set in the file \textit{CPP\_OPTIONS.h }in the directory \textit{%  \subsection{Configuration and setup}
1058  model/inc }or in one of the \textit{code }directories of the case study  
1059  experiments under \textit{verification.} The model parameters are defined  The CPP keys relative to the ``numerical model'' part of the code are
1060  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
1061  values are set in the routine \textit{model/src/set\_defaults.F. }The  directory \textit{ model/inc }or in one of the \textit{code
1062  default values can be modified in the namelist file \textit{data }which  }directories of the case study experiments under
1063  needs to be located in the directory where you will run the model. The  \textit{verification.} The model parameters are defined and declared
1064  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
1065  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
1066  located.  values can be modified in the namelist file \textit{data }which needs
1067    to be located in the directory where you will run the model. The
1068  In what follows the parameters are grouped into categories related to the  parameters are initialized in the routine
1069  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
1070  controls.  part of the namelist the parameters are located.
1071    
1072  \subsubsection{Computational domain, geometry and time-discretization}  In what follows the parameters are grouped into categories related to
1073    the computational domain, the equations solved in the model, and the
1074  \begin{itemize}  simulation controls.
1075  \item dimensions  
1076  \end{itemize}  \subsection{Computational domain, geometry and time-discretization}
1077    
1078  The number of points in the x, y,\textit{\ }and r\textit{\ }directions are  \begin{description}
1079  represented by the variables \textbf{sNx}\textit{, }\textbf{sNy}\textit{, }%  \item[dimensions] \
1080  and \textbf{Nr}\textit{\ }respectively which are declared and set in the    
1081  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
1082  calculation. For multiprocessor calculations see section on parallel    by the variables \textbf{sNx}, \textbf{sNy} and \textbf{Nr}
1083  implementation.)    respectively which are declared and set in the file
1084      \textit{model/inc/SIZE.h}.  (Again, this assumes a mono-processor
1085  \begin{itemize}    calculation. For multiprocessor calculations see the section on
1086  \item grid    parallel implementation.)
1087  \end{itemize}  
1088    \item[grid] \
1089  Three different grids are available: cartesian, spherical polar, and    
1090  curvilinear (including the cubed sphere). The grid is set through the    Three different grids are available: cartesian, spherical polar, and
1091  logical variables \textbf{usingCartesianGrid}\textit{, }\textbf{%    curvilinear (which includes the cubed sphere). The grid is set
1092  usingSphericalPolarGrid}\textit{, }and \textit{\ }\textbf{%    through the logical variables \textbf{usingCartesianGrid},
1093  usingCurvilinearGrid}\textit{. }In the case of spherical and curvilinear    \textbf{usingSphericalPolarGrid}, and \textbf{usingCurvilinearGrid}.
1094  grids, the southern boundary is defined through the variable \textbf{phiMin}%    In the case of spherical and curvilinear grids, the southern
1095  \textit{\ }which corresponds to the latitude of the southern most cell face    boundary is defined through the variable \textbf{phiMin} which
1096  (in degrees). The resolution along the x and y directions is controlled by    corresponds to the latitude of the southern most cell face (in
1097  the 1D arrays \textbf{delx}\textit{\ }and \textbf{dely}\textit{\ }(in meters    degrees). The resolution along the x and y directions is controlled
1098  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
1099  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
1100  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
1101  Ro\_SeaLevel} represents the standard position of Sea-Level in ''R''    meters) or \textbf{delp} for the atmosphere (in Pa).  The variable
1102  coordinate. This is typically set to 0m for the ocean (default value) and 10$%    \textbf{Ro\_SeaLevel} represents the standard position of Sea-Level
1103  ^{5}$Pa for the atmosphere. For the atmosphere, also set the logical    in ``R'' coordinate. This is typically set to 0m for the ocean
1104  variable \textbf{groundAtK1} to '.\texttt{TRUE}.'. which put the first level    (default value) and 10$^{5}$Pa for the atmosphere. For the
1105  (k=1) at the lower boundary (ground).    atmosphere, also set the logical variable \textbf{groundAtK1} to
1106      \texttt{'.TRUE.'} which puts the first level (k=1) at the lower
1107  For the cartesian grid case, the Coriolis parameter $f$ is set through the    boundary (ground).
1108  variables \textbf{f0}\textit{\ }and \textbf{beta}\textit{\ }which correspond    
1109  to the reference Coriolis parameter (in s$^{-1}$) and $\frac{\partial f}{%    For the cartesian grid case, the Coriolis parameter $f$ is set
1110  \partial y}$(in m$^{-1}$s$^{-1}$) respectively. If \textbf{beta }\textit{\ }%    through the variables \textbf{f0} and \textbf{beta} which correspond
1111  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
1112  southern edge of the domain.    $\frac{\partial f}{ \partial y}$(in m$^{-1}$s$^{-1}$) respectively.
1113      If \textbf{beta } is set to a nonzero value, \textbf{f0} is the
1114  \begin{itemize}    value of $f$ at the southern edge of the domain.
1115  \item topography - full and partial cells  
1116  \end{itemize}  \item[topography - full and partial cells] \
1117      
1118  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)
1119  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
1120  file name is represented by the variable \textbf{bathyFile}\textit{. }The    atmosphere. The file name is represented by the variable
1121  file is assumed to contain binary numbers giving the depth (pressure) of the    \textbf{bathyFile}. The file is assumed to contain binary numbers
1122  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
1123  points are ordered from low coordinate to high coordinate for both axes. The    with the x coordinate varying fastest. The points are ordered from
1124  model code applies without modification to enclosed, periodic, and double    low coordinate to high coordinate for both axes. The model code
1125  periodic domains. Periodicity is assumed by default and is suppressed by    applies without modification to enclosed, periodic, and double
1126  setting the depths to 0m for the cells at the limits of the computational    periodic domains. Periodicity is assumed by default and is
1127  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
1128  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
1129  \textbf{readBinaryPrec }which can take the value \texttt{32} (single    atmosphere). The precision with which to read the binary data is
1130  precision) or \texttt{64} (double precision). See the matlab program \textit{%    controlled by the integer variable \textbf{readBinaryPrec} which can
1131  gendata.m }in the \textit{input }directories under \textit{verification }to    take the value \texttt{32} (single precision) or \texttt{64} (double
1132  see how the bathymetry files are generated for the case study experiments.    precision). See the matlab program \textit{gendata.m} in the
1133      \textit{input} directories under \textit{verification} to see how
1134  To use the partial cell capability, the variable \textbf{hFacMin}\textit{\ }%    the bathymetry files are generated for the case study experiments.
1135  needs to be set to a value between 0 and 1 (it is set to 1 by default)    
1136  corresponding to the minimum fractional size of the cell. For example if the    To use the partial cell capability, the variable \textbf{hFacMin}
1137  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
1138  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.
1139  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
1140  bottom depth (in \textbf{bathyFile}) at this point.    set to 0.1, the actual thickness of the cell (i.e. used in the code)
1141      can cover a range of discrete values 50m apart from 50m to 500m
1142  Note that the bottom depths (or pressures) need not coincide with the models    depending on the value of the bottom depth (in \textbf{bathyFile})
1143  levels as deduced from \textbf{delz}\textit{\ }or\textit{\ }\textbf{delp}%    at this point.
1144  \textit{. }The model will interpolate the numbers in \textbf{bathyFile}%    
1145  \textit{\ }so that they match the levels obtained from \textbf{delz}\textit{%    Note that the bottom depths (or pressures) need not coincide with
1146  \ }or\textit{\ }\textbf{delp}\textit{\ }and \textbf{hFacMin}\textit{. }    the models levels as deduced from \textbf{delz} or \textbf{delp}.
1147      The model will interpolate the numbers in \textbf{bathyFile} so that
1148  (Note: the atmospheric case is a bit more complicated than what is written    they match the levels obtained from \textbf{delz} or \textbf{delp}
1149  here I think. To come soon...)    and \textbf{hFacMin}.
1150      
1151  \begin{itemize}    (Note: the atmospheric case is a bit more complicated than what is
1152  \item time-discretization    written here I think. To come soon...)
1153  \end{itemize}  
1154    \item[time-discretization] \
1155  The time steps are set through the real variables \textbf{deltaTMom }and    
1156  \textbf{deltaTtracer }(in s) which represent the time step for the momentum    The time steps are set through the real variables \textbf{deltaTMom}
1157  and tracer equations, respectively. For synchronous integrations, simply set    and \textbf{deltaTtracer} (in s) which represent the time step for
1158  the two variables to the same value (or you can prescribe one time step only    the momentum and tracer equations, respectively. For synchronous
1159  through the variable \textbf{deltaT}). The Adams-Bashforth stabilizing    integrations, simply set the two variables to the same value (or you
1160  parameter is set through the variable \textbf{abEps }(dimensionless). The    can prescribe one time step only through the variable
1161  stagger baroclinic time stepping can be activated by setting the logical    \textbf{deltaT}). The Adams-Bashforth stabilizing parameter is set
1162  variable \textbf{staggerTimeStep }to '.\texttt{TRUE}.'.    through the variable \textbf{abEps} (dimensionless). The stagger
1163      baroclinic time stepping can be activated by setting the logical
1164  \subsubsection{Equation of state}    variable \textbf{staggerTimeStep} to \texttt{'.TRUE.'}.
1165    
1166  First, because the model equations are written in terms of perturbations, a  \end{description}
1167  reference thermodynamic state needs to be specified. This is done through  
1168  the 1D arrays \textbf{tRef}\textit{\ }and \textbf{sRef}. \textbf{tRef }%  
1169  specifies the reference potential temperature profile (in $^{o}$C for  \subsection{Equation of state}
1170  the ocean and $^{o}$K for the atmosphere) starting from the level  
1171  k=1. Similarly, \textbf{sRef}\textit{\ }specifies the reference salinity  First, because the model equations are written in terms of
1172  profile (in ppt) for the ocean or the reference specific humidity profile  perturbations, a reference thermodynamic state needs to be specified.
1173  (in g/kg) for the atmosphere.  This is done through the 1D arrays \textbf{tRef} and \textbf{sRef}.
1174    \textbf{tRef} specifies the reference potential temperature profile
1175  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
1176  \textbf{buoyancyRelation}\textit{\ }and \textbf{eosType}\textit{. }\textbf{%  from the level k=1. Similarly, \textbf{sRef} specifies the reference
1177  buoyancyRelation}\textit{\ }is set to '\texttt{OCEANIC}' by default and  salinity profile (in ppt) for the ocean or the reference specific
1178  needs to be set to '\texttt{ATMOSPHERIC}' for atmosphere simulations. In  humidity profile (in g/kg) for the atmosphere.
1179  this case, \textbf{eosType}\textit{\ }must be set to '\texttt{IDEALGAS}'.  
1180  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
1181  \textbf{eosType}\textit{\ }to '\texttt{LINEAR}') and a polynomial  variables \textbf{buoyancyRelation} and \textbf{eosType}.
1182  approximation to the full nonlinear equation ( set \textbf{eosType}\textit{\  \textbf{buoyancyRelation} is set to \texttt{'OCEANIC'} by default and
1183  }to '\texttt{POLYNOMIAL}'). In the linear case, you need to specify the  needs to be set to \texttt{'ATMOSPHERIC'} for atmosphere simulations.
1184  thermal and haline expansion coefficients represented by the variables  In this case, \textbf{eosType} must be set to \texttt{'IDEALGAS'}.
1185  \textbf{tAlpha}\textit{\ }(in K$^{-1}$) and \textbf{sBeta}\textit{\ }(in ppt$%  For the ocean, two forms of the equation of state are available:
1186  ^{-1}$). For the nonlinear case, you need to generate a file of polynomial  linear (set \textbf{eosType} to \texttt{'LINEAR'}) and a polynomial
1187  coefficients called \textit{POLY3.COEFFS. }To do this, use the program  approximation to the full nonlinear equation ( set \textbf{eosType} to
1188  \textit{utils/knudsen2/knudsen2.f }under the model tree (a Makefile is  \texttt{'POLYNOMIAL'}). In the linear case, you need to specify the
1189  available in the same directory and you will need to edit the number and the  thermal and haline expansion coefficients represented by the variables
1190  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
1191  those of your configuration). \textit{\ }  the nonlinear case, you need to generate a file of polynomial
1192    coefficients called \textit{POLY3.COEFFS}. To do this, use the program
1193  \subsubsection{Momentum equations}  \textit{utils/knudsen2/knudsen2.f} under the model tree (a Makefile is
1194    available in the same directory and you will need to edit the number
1195  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
1196  to change, i.e. the ones relative to forcing and dissipation for example.  they match those of your configuration).
1197  The details relevant to the vector-invariant form of the equations and the  
1198  various advection schemes are not covered for the moment. We assume that you  There there are also higher polynomials for the equation of state:
1199  use the standard form of the momentum equations (i.e. the flux-form) with  \begin{description}
1200  the default advection scheme. Also, there are a few logical variables that  \item[\texttt{'UNESCO'}:] The UNESCO equation of state formula of
1201  allow you to turn on/off various terms in the momentum equation. These    Fofonoff and Millard \cite{fofonoff83}. This equation of state
1202  variables are called \textbf{momViscosity, momAdvection, momForcing,    assumes in-situ temperature, which is not a model variable; {\em its
1203  useCoriolis, momPressureForcing, momStepping}\textit{, }and \textit{\ }%      use is therefore discouraged, and it is only listed for
1204  \textbf{metricTerms }and are assumed to be set to '.\texttt{TRUE}.' here.      completeness}.
1205  Look at the file \textit{model/inc/PARAMS.h }for a precise definition of  \item[\texttt{'JMD95Z'}:] A modified UNESCO formula by Jackett and
1206  these variables.    McDougall \cite{jackett95}, which uses the model variable potential
1207      temperature as input. The \texttt{'Z'} indicates that this equation
1208  \begin{itemize}    of state uses a horizontally and temporally constant pressure
1209  \item initialization    $p_{0}=-g\rho_{0}z$.
1210  \end{itemize}  \item[\texttt{'JMD95P'}:] A modified UNESCO formula by Jackett and
1211      McDougall \cite{jackett95}, which uses the model variable potential
1212  The velocity components are initialized to 0 unless the simulation is    temperature as input. The \texttt{'P'} indicates that this equation
1213  starting from a pickup file (see section on simulation control parameters).    of state uses the actual hydrostatic pressure of the last time
1214      step. Lagging the pressure in this way requires an additional pickup
1215  \begin{itemize}    file for restarts.
1216  \item forcing  \item[\texttt{'MDJWF'}:] The new, more accurate and less expensive
1217  \end{itemize}    equation of state by McDougall et~al. \cite{mcdougall03}. It also
1218      requires lagging the pressure and therefore an additional pickup
1219  This section only applies to the ocean. You need to generate wind-stress    file for restarts.
1220  data into two files \textbf{zonalWindFile}\textit{\ }and \textbf{%  \end{description}
1221  meridWindFile }corresponding to the zonal and meridional components of the  For none of these options an reference profile of temperature or
1222  wind stress, respectively (if you want the stress to be along the direction  salinity is required.
1223  of only one of the model horizontal axes, you only need to generate one  
1224  file). The format of the files is similar to the bathymetry file. The zonal  \subsection{Momentum equations}
1225  (meridional) stress data are assumed to be in Pa and located at U-points  
1226  (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
1227  binary data is controlled by the variable \textbf{readBinaryPrec}.\textbf{\ }  likely to change, i.e. the ones relative to forcing and dissipation
1228  See the matlab program \textit{gendata.m }in the \textit{input }directories  for example.  The details relevant to the vector-invariant form of the
1229  under \textit{verification }to see how simple analytical wind forcing data  equations and the various advection schemes are not covered for the
1230  are generated for the case study experiments.  moment. We assume that you use the standard form of the momentum
1231    equations (i.e. the flux-form) with the default advection scheme.
1232  There is also the possibility of prescribing time-dependent periodic  Also, there are a few logical variables that allow you to turn on/off
1233  forcing. To do this, concatenate the successive time records into a single  various terms in the momentum equation. These variables are called
1234  file (for each stress component) ordered in a (x, y, t) fashion and set the  \textbf{momViscosity, momAdvection, momForcing, useCoriolis,
1235  following variables: \textbf{periodicExternalForcing }to '.\texttt{TRUE}.',    momPressureForcing, momStepping} and \textbf{metricTerms }and are
1236  \textbf{externForcingPeriod }to the period (in s) of which the forcing  assumed to be set to \texttt{'.TRUE.'} here.  Look at the file
1237  varies (typically 1 month), and \textbf{externForcingCycle }to the repeat  \textit{model/inc/PARAMS.h }for a precise definition of these
1238  time (in s) of the forcing (typically 1 year -- note: \textbf{%  variables.
1239  externForcingCycle }must be a multiple of \textbf{externForcingPeriod}).  
1240  With these variables set up, the model will interpolate the forcing linearly  \begin{description}
1241  at each iteration.  \item[initialization] \
1242      
1243  \begin{itemize}    The velocity components are initialized to 0 unless the simulation
1244  \item dissipation    is starting from a pickup file (see section on simulation control
1245  \end{itemize}    parameters).
1246    
1247  The lateral eddy viscosity coefficient is specified through the variable  \item[forcing] \
1248  \textbf{viscAh}\textit{\ }(in m$^{2}$s$^{-1}$). The vertical eddy viscosity    
1249  coefficient is specified through the variable \textbf{viscAz }(in m$^{2}$s$%    This section only applies to the ocean. You need to generate
1250  ^{-1}$) for the ocean and \textbf{viscAp}\textit{\ }(in Pa$^{2}$s$^{-1}$)    wind-stress data into two files \textbf{zonalWindFile} and
1251  for the atmosphere. The vertical diffusive fluxes can be computed implicitly    \textbf{meridWindFile} corresponding to the zonal and meridional
1252  by setting the logical variable \textbf{implicitViscosity }to '.\texttt{TRUE}%    components of the wind stress, respectively (if you want the stress
1253  .'. 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,
1254  \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
1255  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
1256  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
1257  viscosity. Slip or no-slip conditions at lateral and bottom boundaries are    the bathymetry, the precision with which to read the binary data is
1258  specified through the logical variables \textbf{no\_slip\_sides}\textit{\ }%    controlled by the variable \textbf{readBinaryPrec}.  See the matlab
1259  and \textbf{no\_slip\_bottom}. If set to '\texttt{.FALSE.}', free-slip    program \textit{gendata.m} in the \textit{input} directories under
1260  boundary conditions are applied. If no-slip boundary conditions are applied    \textit{verification} to see how simple analytical wind forcing data
1261  at the bottom, a bottom drag can be applied as well. Two forms are    are generated for the case study experiments.
1262  available: linear (set the variable \textbf{bottomDragLinear}\textit{\ }in s$%    
1263  ^{-1}$) and quadratic (set the variable \textbf{bottomDragQuadratic}\textit{%    There is also the possibility of prescribing time-dependent periodic
1264  \ }in m$^{-1}$).    forcing. To do this, concatenate the successive time records into a
1265      single file (for each stress component) ordered in a (x,y,t) fashion
1266  The Fourier and Shapiro filters are described elsewhere.    and set the following variables: \textbf{periodicExternalForcing }to
1267      \texttt{'.TRUE.'}, \textbf{externForcingPeriod }to the period (in s)
1268  \begin{itemize}    of which the forcing varies (typically 1 month), and
1269  \item C-D scheme    \textbf{externForcingCycle} to the repeat time (in s) of the forcing
1270  \end{itemize}    (typically 1 year -- note: \textbf{ externForcingCycle} must be a
1271      multiple of \textbf{externForcingPeriod}).  With these variables set
1272  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
1273  for the computation of the Coriolis terms. The variable\textbf{\ tauCD},    iteration.
1274  which represents the C-D scheme coupling timescale (in s) needs to be set.  
1275    \item[dissipation] \
1276  \begin{itemize}    
1277  \item calculation of pressure/geopotential    The lateral eddy viscosity coefficient is specified through the
1278  \end{itemize}    variable \textbf{viscAh} (in m$^{2}$s$^{-1}$). The vertical eddy
1279      viscosity coefficient is specified through the variable
1280  First, to run a non-hydrostatic ocean simulation, set the logical variable    \textbf{viscAz} (in m$^{2}$s$^{-1}$) for the ocean and
1281  \textbf{nonHydrostatic} to '.\texttt{TRUE}.'. The pressure field is then    \textbf{viscAp} (in Pa$^{2}$s$^{-1}$) for the atmosphere.  The
1282  inverted through a 3D elliptic equation. (Note: this capability is not    vertical diffusive fluxes can be computed implicitly by setting the
1283  available for the atmosphere yet.) By default, a hydrostatic simulation is    logical variable \textbf{implicitViscosity }to \texttt{'.TRUE.'}.
1284  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
1285  parameters controlling the behaviour of the elliptic solvers are the    variable \textbf{viscA4} (in m$^{4}$s$^{-1}$). On a spherical polar
1286  variables \textbf{cg2dMaxIters}\textit{\ }and \textbf{cg2dTargetResidual }%    grid, you might also need to set the variable \textbf{cosPower}
1287  for the 2D case and \textbf{cg3dMaxIters}\textit{\ }and \textbf{%    which is set to 0 by default and which represents the power of
1288  cg3dTargetResidual }for the 3D case. You probably won't need to alter the    cosine of latitude to multiply viscosity. Slip or no-slip conditions
1289  default values (are we sure of this?).    at lateral and bottom boundaries are specified through the logical
1290      variables \textbf{no\_slip\_sides} and \textbf{no\_slip\_bottom}. If
1291  For the calculation of the surface pressure (for the ocean) or surface    set to \texttt{'.FALSE.'}, free-slip boundary conditions are
1292  geopotential (for the atmosphere) you need to set the logical variables    applied. If no-slip boundary conditions are applied at the bottom, a
1293  \textbf{rigidLid} and \textbf{implicitFreeSurface}\textit{\ }(set one to '.%    bottom drag can be applied as well. Two forms are available: linear
1294  \texttt{TRUE}.' and the other to '.\texttt{FALSE}.' depending on how you    (set the variable \textbf{bottomDragLinear} in s$ ^{-1}$) and
1295  want to deal with the ocean upper or atmosphere lower boundary).    quadratic (set the variable \textbf{bottomDragQuadratic} in
1296      m$^{-1}$).
1297  \subsubsection{Tracer equations}  
1298      The Fourier and Shapiro filters are described elsewhere.
1299  This section covers the tracer equations i.e. the potential temperature  
1300  equation and the salinity (for the ocean) or specific humidity (for the  \item[C-D scheme] \
1301  atmosphere) equation. As for the momentum equations, we only describe for    
1302  now the parameters that you are likely to change. The logical variables    If you run at a sufficiently coarse resolution, you will need the
1303  \textbf{tempDiffusion}\textit{, }\textbf{tempAdvection}\textit{, }\textbf{%    C-D scheme for the computation of the Coriolis terms. The
1304  tempForcing}\textit{,} and \textbf{tempStepping} allow you to turn on/off    variable\textbf{\ tauCD}, which represents the C-D scheme coupling
1305  terms in the temperature equation (same thing for salinity or specific    timescale (in s) needs to be set.
1306  humidity with variables \textbf{saltDiffusion}\textit{, }\textbf{%    
1307  saltAdvection}\textit{\ }etc). These variables are all assumed here to be  \item[calculation of pressure/geopotential] \
1308  set to '.\texttt{TRUE}.'. Look at file \textit{model/inc/PARAMS.h }for a    
1309  precise definition.    First, to run a non-hydrostatic ocean simulation, set the logical
1310      variable \textbf{nonHydrostatic} to \texttt{'.TRUE.'}. The pressure
1311  \begin{itemize}    field is then inverted through a 3D elliptic equation. (Note: this
1312  \item initialization    capability is not available for the atmosphere yet.) By default, a
1313  \end{itemize}    hydrostatic simulation is assumed and a 2D elliptic equation is used
1314      to invert the pressure field. The parameters controlling the
1315  The initial tracer data can be contained in the binary files \textbf{%    behaviour of the elliptic solvers are the variables
1316  hydrogThetaFile }and \textbf{hydrogSaltFile}. These files should contain 3D    \textbf{cg2dMaxIters} and \textbf{cg2dTargetResidual } for
1317  data ordered in an (x, y, r) fashion with k=1 as the first vertical level.    the 2D case and \textbf{cg3dMaxIters} and
1318  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
1319  values of \textbf{tRef }and \textbf{sRef }mentioned above (in the equation    alter the default values (are we sure of this?).
1320  of state section). In this case, the initial tracer data are uniform in x    
1321  and y for each depth level.    For the calculation of the surface pressure (for the ocean) or
1322      surface geopotential (for the atmosphere) you need to set the
1323  \begin{itemize}    logical variables \textbf{rigidLid} and \textbf{implicitFreeSurface}
1324  \item forcing    (set one to \texttt{'.TRUE.'} and the other to \texttt{'.FALSE.'}
1325  \end{itemize}    depending on how you want to deal with the ocean upper or atmosphere
1326      lower boundary).
1327  This part is more relevant for the ocean, the procedure for the atmosphere  
1328  not being completely stabilized at the moment.  \end{description}
1329    
1330  A combination of fluxes data and relaxation terms can be used for driving  \subsection{Tracer equations}
1331  the tracer equations. \ For potential temperature, heat flux data (in W/m$%  
1332  ^{2}$) can be stored in the 2D binary file \textbf{surfQfile}\textit{. }%  This section covers the tracer equations i.e. the potential
1333  Alternatively or in addition, the forcing can be specified through a  temperature equation and the salinity (for the ocean) or specific
1334  relaxation term. The SST data to which the model surface temperatures are  humidity (for the atmosphere) equation. As for the momentum equations,
1335  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.
1336  thetaClimFile}\textit{. }The corresponding relaxation time scale coefficient  The logical variables \textbf{tempDiffusion} \textbf{tempAdvection}
1337  is set through the variable \textbf{tauThetaClimRelax}\textit{\ }(in s). The  \textbf{tempForcing}, and \textbf{tempStepping} allow you to turn
1338  same procedure applies for salinity with the variable names \textbf{EmPmRfile%  on/off terms in the temperature equation (same thing for salinity or
1339  }\textit{, }\textbf{saltClimFile}\textit{, }and \textbf{tauSaltClimRelax}%  specific humidity with variables \textbf{saltDiffusion},
1340  \textit{\ }for freshwater flux (in m/s) and surface salinity (in ppt) data  \textbf{saltAdvection} etc.). These variables are all assumed here to
1341  files and relaxation time scale coefficient (in s), respectively. Also for  be set to \texttt{'.TRUE.'}. Look at file \textit{model/inc/PARAMS.h}
1342  salinity, if the CPP key \textbf{USE\_NATURAL\_BCS} is turned on, natural  for a precise definition.
1343  boundary conditions are applied i.e. when computing the surface salinity  
1344  tendency, the freshwater flux is multiplied by the model surface salinity  \begin{description}
1345  instead of a constant salinity value.  \item[initialization] \
1346      
1347  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
1348  controlled by the variable \textbf{readBinaryPrec}. Time-dependent, periodic    \textbf{hydrogThetaFile} and \textbf{hydrogSaltFile}. These files
1349  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
1350  wind forcing data (see above).    first vertical level.  If no file names are provided, the tracers
1351      are then initialized with the values of \textbf{tRef} and
1352  \begin{itemize}    \textbf{sRef} mentioned above (in the equation of state section). In
1353  \item dissipation    this case, the initial tracer data are uniform in x and y for each
1354  \end{itemize}    depth level.
1355    
1356  Lateral eddy diffusivities for temperature and salinity/specific humidity  \item[forcing] \
1357  are specified through the variables \textbf{diffKhT }and \textbf{diffKhS }%    
1358  (in m$^{2}$/s). Vertical eddy diffusivities are specified through the    This part is more relevant for the ocean, the procedure for the
1359  variables \textbf{diffKzT }and \textbf{diffKzS }(in m$^{2}$/s) for the ocean    atmosphere not being completely stabilized at the moment.
1360  and \textbf{diffKpT }and \textbf{diffKpS }(in Pa$^{2}$/s) for the    
1361  atmosphere. The vertical diffusive fluxes can be computed implicitly by    A combination of fluxes data and relaxation terms can be used for
1362  setting the logical variable \textbf{implicitDiffusion }to '.\texttt{TRUE}%    driving the tracer equations.  For potential temperature, heat flux
1363  .'. In addition, biharmonic diffusivities can be specified as well through    data (in W/m$ ^{2}$) can be stored in the 2D binary file
1364  the coefficients \textbf{diffK4T }and \textbf{diffK4S }(in m$^{4}$/s). Note    \textbf{surfQfile}.  Alternatively or in addition, the forcing can
1365  that the cosine power scaling (specified through \textbf{cosPower }- see the    be specified through a relaxation term. The SST data to which the
1366  momentum equations section) is applied to the tracer diffusivities    model surface temperatures are restored to are supposed to be stored
1367  (Laplacian and biharmonic) as well. The Gent and McWilliams parameterization    in the 2D binary file \textbf{thetaClimFile}. The corresponding
1368  for oceanic tracers is described in the package section. Finally, note that    relaxation time scale coefficient is set through the variable
1369  tracers can be also subject to Fourier and Shapiro filtering (see the    \textbf{tauThetaClimRelax} (in s). The same procedure applies for
1370  corresponding section on these filters).    salinity with the variable names \textbf{EmPmRfile},
1371      \textbf{saltClimFile}, and \textbf{tauSaltClimRelax} for freshwater
1372  \begin{itemize}    flux (in m/s) and surface salinity (in ppt) data files and
1373  \item ocean convection    relaxation time scale coefficient (in s), respectively. Also for
1374  \end{itemize}    salinity, if the CPP key \textbf{USE\_NATURAL\_BCS} is turned on,
1375      natural boundary conditions are applied i.e. when computing the
1376  Two options are available to parameterize ocean convection: one is to use    surface salinity tendency, the freshwater flux is multiplied by the
1377  the convective adjustment scheme. In this case, you need to set the variable    model surface salinity instead of a constant salinity value.
1378  \textbf{cadjFreq}, which represents the frequency (in s) with which the    
1379  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
1380  value by the user, the model will set it to the tracer time step). The other    data is controlled by the variable \textbf{readBinaryPrec}.
1381  option is to parameterize convection with implicit vertical diffusion. To do    Time-dependent, periodic forcing can be applied as well following
1382  this, set the logical variable \textbf{implicitDiffusion }to '.\texttt{TRUE}%    the same procedure used for the wind forcing data (see above).
1383  .' and the real variable \textbf{ivdc\_kappa }to a value (in m$^{2}$/s) you  
1384  wish the tracer vertical diffusivities to have when mixing tracers  \item[dissipation] \
1385  vertically due to static instabilities. Note that \textbf{cadjFreq }and    
1386  \textbf{ivdc\_kappa }can not both have non-zero value.    Lateral eddy diffusivities for temperature and salinity/specific
1387      humidity are specified through the variables \textbf{diffKhT} and
1388  \subsubsection{Simulation controls}    \textbf{diffKhS} (in m$^{2}$/s). Vertical eddy diffusivities are
1389      specified through the variables \textbf{diffKzT} and
1390  The model ''clock'' is defined by the variable \textbf{deltaTClock }(in s)    \textbf{diffKzS} (in m$^{2}$/s) for the ocean and \textbf{diffKpT
1391  which determines the IO frequencies and is used in tagging output.    }and \textbf{diffKpS} (in Pa$^{2}$/s) for the atmosphere. The
1392  Typically, you will set it to the tracer time step for accelerated runs    vertical diffusive fluxes can be computed implicitly by setting the
1393  (otherwise it is simply set to the default time step \textbf{deltaT}).    logical variable \textbf{implicitDiffusion} to \texttt{'.TRUE.'}.
1394  Frequency of checkpointing and dumping of the model state are referenced to    In addition, biharmonic diffusivities can be specified as well
1395  this clock (see below).    through the coefficients \textbf{diffK4T} and \textbf{diffK4S} (in
1396      m$^{4}$/s). Note that the cosine power scaling (specified through
1397  \begin{itemize}    \textbf{cosPower}---see the momentum equations section) is applied to
1398  \item run duration    the tracer diffusivities (Laplacian and biharmonic) as well. The
1399  \end{itemize}    Gent and McWilliams parameterization for oceanic tracers is
1400      described in the package section. Finally, note that tracers can be
1401  The beginning of a simulation is set by specifying a start time (in s)    also subject to Fourier and Shapiro filtering (see the corresponding
1402  through the real variable \textbf{startTime }or by specifying an initial    section on these filters).
1403  iteration number through the integer variable \textbf{nIter0}. If these  
1404  variables are set to nonzero values, the model will look for a ''pickup''  \item[ocean convection] \
1405  file \textit{pickup.0000nIter0 }to restart the integration\textit{. }The end    
1406  of a simulation is set through the real variable \textbf{endTime }(in s).    Two options are available to parameterize ocean convection: one is
1407  Alternatively, you can specify instead the number of time steps to execute    to use the convective adjustment scheme. In this case, you need to
1408  through the integer variable \textbf{nTimeSteps}.    set the variable \textbf{cadjFreq}, which represents the frequency
1409      (in s) with which the adjustment algorithm is called, to a non-zero
1410  \begin{itemize}    value (if set to a negative value by the user, the model will set it
1411  \item frequency of output    to the tracer time step). The other option is to parameterize
1412  \end{itemize}    convection with implicit vertical diffusion. To do this, set the
1413      logical variable \textbf{implicitDiffusion} to \texttt{'.TRUE.'}
1414  Real variables defining frequencies (in s) with which output files are    and the real variable \textbf{ivdc\_kappa} to a value (in m$^{2}$/s)
1415  written on disk need to be set up. \textbf{dumpFreq }controls the frequency    you wish the tracer vertical diffusivities to have when mixing
1416  with which the instantaneous state of the model is saved. \textbf{chkPtFreq }%    tracers vertically due to static instabilities. Note that
1417  and \textbf{pchkPtFreq }control the output frequency of rolling and    \textbf{cadjFreq} and \textbf{ivdc\_kappa}can not both have non-zero
1418  permanent checkpoint files, respectively. See section 1.5.1 Output files for the    value.
1419  definition of model state and checkpoint files. In addition, time-averaged  
1420  fields can be written out by setting the variable \textbf{taveFreq} (in s).  \end{description}
1421  The precision with which to write the binary data is controlled by the  
1422  integer variable w\textbf{riteBinaryPrec }(set it to \texttt{32} or \texttt{%  \subsection{Simulation controls}
1423  64}).  
1424    The model ''clock'' is defined by the variable \textbf{deltaTClock}
1425    (in s) which determines the IO frequencies and is used in tagging
1426    output.  Typically, you will set it to the tracer time step for
1427    accelerated runs (otherwise it is simply set to the default time step
1428    \textbf{deltaT}).  Frequency of checkpointing and dumping of the model
1429    state are referenced to this clock (see below).
1430    
1431    \begin{description}
1432    \item[run duration] \
1433      
1434      The beginning of a simulation is set by specifying a start time (in
1435      s) through the real variable \textbf{startTime} or by specifying an
1436      initial iteration number through the integer variable
1437      \textbf{nIter0}. If these variables are set to nonzero values, the
1438      model will look for a ''pickup'' file \textit{pickup.0000nIter0} to
1439      restart the integration. The end of a simulation is set through the
1440      real variable \textbf{endTime} (in s).  Alternatively, you can
1441      specify instead the number of time steps to execute through the
1442      integer variable \textbf{nTimeSteps}.
1443    
1444    \item[frequency of output] \
1445      
1446      Real variables defining frequencies (in s) with which output files
1447      are written on disk need to be set up. \textbf{dumpFreq} controls
1448      the frequency with which the instantaneous state of the model is
1449      saved. \textbf{chkPtFreq} and \textbf{pchkPtFreq} control the output
1450      frequency of rolling and permanent checkpoint files, respectively.
1451      See section 1.5.1 Output files for the definition of model state and
1452      checkpoint files. In addition, time-averaged fields can be written
1453      out by setting the variable \textbf{taveFreq} (in s).  The precision
1454      with which to write the binary data is controlled by the integer
1455      variable w\textbf{riteBinaryPrec} (set it to \texttt{32} or
1456      \texttt{64}).
1457    
1458    \end{description}
1459    
1460    
1461    %%% Local Variables:
1462    %%% mode: latex
1463    %%% TeX-master: t
1464    %%% End:

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