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3    
4  %\section{Getting started}  %\section{Getting started}
5    
6  In this section, we describe how to use the model. In the first  We believe the best way to familiarize yourself with the
 section, we provide enough information to help you get started with  
 the model. We believe the best way to familiarize yourself with the  
7  model is to run the case study examples provided with the base  model is to run the case study examples provided with the base
8  version. Information on how to obtain, compile, and run the code is  version. Information on how to obtain, compile, and run the code is
9  found there as well as a brief description of the model structure  found here as well as a brief description of the model structure
10  directory and the case study examples.  The latter and the code  directory and the case study examples. Information is also provided
11  structure are described more fully in chapters  here on how to customize the code when you are ready to try implementing
12  \ref{chap:discretization} and \ref{chap:sarch}, respectively. Here, in  the configuration you have in mind.  The code and algorithm
13  this section, we provide information on how to customize the code when  are described more fully in chapters \ref{chap:discretization} and
14  you are ready to try implementing the configuration you have in mind.  \ref{chap:sarch}.
15    
16  \section{Where to find information}  \section{Where to find information}
17  \label{sect:whereToFindInfo}  \label{sect:whereToFindInfo}
18    \begin{rawhtml}
19  A web site is maintained for release 1 (Sealion) of MITgcm:  <!-- CMIREDIR:whereToFindInfo: -->
20    \end{rawhtml}
21    
22    There is a web-archived support mailing list for the model that
23    you can email at \texttt{MITgcm-support@mitgcm.org} or browse at:
24    \begin{rawhtml} <A href=http://mitgcm.org/mailman/listinfo/mitgcm-support/ target="idontexist"> \end{rawhtml}
25  \begin{verbatim}  \begin{verbatim}
26  http://mitgcm.org/sealion  http://mitgcm.org/mailman/listinfo/mitgcm-support/
27    http://mitgcm.org/pipermail/mitgcm-support/
28  \end{verbatim}  \end{verbatim}
29  Here you will find an on-line version of this document, a  \begin{rawhtml} </A> \end{rawhtml}
 ``browsable'' copy of the code and a searchable database of the model  
 and site, as well as links for downloading the model and  
 documentation, to data-sources and other related sites.  
   
 There is also a support news group for the model that you can email at  
 \texttt{support@mitgcm.org} or browse at:  
 \begin{verbatim}  
 news://mitgcm.org/mitgcm.support  
 \end{verbatim}  
 A mail to the email list will reach all the developers and be archived  
 on the newsgroup. A users email list will be established at some time  
 in the future.  
   
30    
31  \section{Obtaining the code}  \section{Obtaining the code}
32  \label{sect:obtainingCode}  \label{sect:obtainingCode}
33    \begin{rawhtml}
34    <!-- CMIREDIR:obtainingCode: -->
35    \end{rawhtml}
36    
37    MITgcm can be downloaded from our system by following
38    the instructions below. As a courtesy we ask that you send e-mail to us at
39    \begin{rawhtml} <A href=mailto:MITgcm-support@mitgcm.org> \end{rawhtml}
40    MITgcm-support@mitgcm.org
41    \begin{rawhtml} </A> \end{rawhtml}
42    to enable us to keep track of who's using the model and in what application.
43    You can download the model two ways:
44    
45    \begin{enumerate}
46    \item Using CVS software. CVS is a freely available source code management
47    tool. To use CVS you need to have the software installed. Many systems
48    come with CVS pre-installed, otherwise good places to look for
49    the software for a particular platform are
50    \begin{rawhtml} <A href=http://www.cvshome.org/ target="idontexist"> \end{rawhtml}
51    cvshome.org
52    \begin{rawhtml} </A> \end{rawhtml}
53    and
54    \begin{rawhtml} <A href=http://www.wincvs.org/ target="idontexist"> \end{rawhtml}
55    wincvs.org
56    \begin{rawhtml} </A> \end{rawhtml}
57    .
58    
59    \item Using a tar file. This method is simple and does not
60    require any special software. However, this method does not
61    provide easy support for maintenance updates.
62    
63    \end{enumerate}
64    
65    \subsection{Method 1 - Checkout from CVS}
66    \label{sect:cvs_checkout}
67    
68  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
69  provides an efficient and elegant way of organizing your code and keeping  provides an efficient and elegant way of organizing your code and keeping
70  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
71  download a tar file.  download a tar file.
72    
73  Before you can use CVS, the following environment variable has to be set in  Before you can use CVS, the following environment variable(s) should
74  your .cshrc or .tcshrc:  be set within your shell.  For a csh or tcsh shell, put the following
75  \begin{verbatim}  \begin{verbatim}
76  % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/u0/gcmpack  % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/gcmpack
77  \end{verbatim}  \end{verbatim}
78    in your \texttt{.cshrc} or \texttt{.tcshrc} file.  For bash or sh
79  To start using CVS, "login" to the server using:  shells, put:
80  \begin{verbatim}  \begin{verbatim}
81  % cvs login ( CVS password: cvsanon )  % export CVSROOT=':pserver:cvsanon@mitgcm.org:/u/gcmpack'
82  \end{verbatim}  \end{verbatim}
83  You only need to do ``cvs login'' once.  in your \texttt{.profile} or \texttt{.bashrc} file.
84    
85    
86  To obtain the source for the release:  To get MITgcm through CVS, first register with the MITgcm CVS server
87    using command:
88  \begin{verbatim}  \begin{verbatim}
89  % cvs co -d directory -P -r release1 MITgcmUV  % cvs login ( CVS password: cvsanon )
90  \end{verbatim}  \end{verbatim}
91    You only need to do a ``cvs login'' once.
92    
93  This creates a directory called \textit{directory}. If \textit{directory}  To obtain the latest sources type:
 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:  
94  \begin{verbatim}  \begin{verbatim}
95  % cvs co -d directory -P -r version MITgcm  % cvs co MITgcm
96  \end{verbatim}  \end{verbatim}
97  or the latest development version:  or to get a specific release type:
98  \begin{verbatim}  \begin{verbatim}
99  % cvs co -d directory -P MITgcm  % cvs co -P -r checkpoint52i_post  MITgcm
100  \end{verbatim}  \end{verbatim}
101    The MITgcm web site contains further directions concerning the source
102    code and CVS.  It also contains a web interface to our CVS archive so
103    that one may easily view the state of files, revisions, and other
104    development milestones:
105    %\begin{rawhtml} <A href="http://mitgcm.org/download" target="idontexist"> \end{rawhtml}
106    \begin{rawhtml} <A href="http://mitgcm.org/viewvc/MITgcm/MITgcm/" target="idontexist"> \end{rawhtml}
107    \begin{verbatim}
108    http://mitgcm.org/source_code.html
109    \end{verbatim}
110    \begin{rawhtml} </A> \end{rawhtml}
111    
112    As a convenience, the MITgcm CVS server contains aliases which are
113    named subsets of the codebase.  These aliases can be especially
114    helpful when used over slow internet connections or on machines with
115    restricted storage space.  Table \ref{tab:cvsModules} contains a list
116    of CVS aliases
117    \begin{table}[htb]
118      \centering
119      \begin{tabular}[htb]{|lp{3.25in}|}\hline
120        \textbf{Alias Name}    &  \textbf{Information (directories) Contained}  \\\hline
121        \texttt{MITgcm\_code}  &  Only the source code -- none of the verification examples.  \\
122        \texttt{MITgcm\_verif\_basic}
123        &  Source code plus a small set of the verification examples
124        (\texttt{global\_ocean.90x40x15}, \texttt{aim.5l\_cs}, \texttt{hs94.128x64x5},
125        \texttt{front\_relax}, and \texttt{plume\_on\_slope}).  \\
126        \texttt{MITgcm\_verif\_atmos}  &  Source code plus all of the atmospheric examples.  \\
127        \texttt{MITgcm\_verif\_ocean}  &  Source code plus all of the oceanic examples.  \\
128        \texttt{MITgcm\_verif\_all}    &  Source code plus all of the
129        verification examples. \\\hline
130      \end{tabular}
131      \caption{MITgcm CVS Modules}
132      \label{tab:cvsModules}
133    \end{table}
134    
135    The checkout process creates a directory called \texttt{MITgcm}. If
136    the directory \texttt{MITgcm} exists this command updates your code
137    based on the repository. Each directory in the source tree contains a
138    directory \texttt{CVS}. This information is required by CVS to keep
139    track of your file versions with respect to the repository. Don't edit
140    the files in \texttt{CVS}!  You can also use CVS to download code
141    updates.  More extensive information on using CVS for maintaining
142    MITgcm code can be found
143    \begin{rawhtml} <A href="http://mitgcm.org/public/using_cvs.html" target="idontexist"> \end{rawhtml}
144    here
145    \begin{rawhtml} </A> \end{rawhtml}
146    .
147    It is important to note that the CVS aliases in Table
148    \ref{tab:cvsModules} cannot be used in conjunction with the CVS
149    \texttt{-d DIRNAME} option.  However, the \texttt{MITgcm} directories
150    they create can be changed to a different name following the check-out:
151    \begin{verbatim}
152       %  cvs co MITgcm_verif_basic
153       %  mv MITgcm MITgcm_verif_basic
154    \end{verbatim}
155    
156    \subsubsection{Upgrading from an earlier version}
157    
158    If you already have an earlier version of the code you can ``upgrade''
159    your copy instead of downloading the entire repository again. First,
160    ``cd'' (change directory) to the top of your working copy:
161    \begin{verbatim}
162    % cd MITgcm
163    \end{verbatim}
164    and then issue the cvs update command such as:
165    \begin{verbatim}
166    % cvs -q update -r checkpoint52i_post -d -P
167    \end{verbatim}
168    This will update the ``tag'' to ``checkpoint52i\_post'', add any new
169    directories (-d) and remove any empty directories (-P). The -q option
170    means be quiet which will reduce the number of messages you'll see in
171    the terminal. If you have modified the code prior to upgrading, CVS
172    will try to merge your changes with the upgrades. If there is a
173    conflict between your modifications and the upgrade, it will report
174    that file with a ``C'' in front, e.g.:
175    \begin{verbatim}
176    C model/src/ini_parms.F
177    \end{verbatim}
178    If the list of conflicts scrolled off the screen, you can re-issue the
179    cvs update command and it will report the conflicts. Conflicts are
180    indicated in the code by the delimites ``$<<<<<<<$'', ``======='' and
181    ``$>>>>>>>$''. For example,
182    {\small
183    \begin{verbatim}
184    <<<<<<< ini_parms.F
185         & bottomDragLinear,myOwnBottomDragCoefficient,
186    =======
187         & bottomDragLinear,bottomDragQuadratic,
188    >>>>>>> 1.18
189    \end{verbatim}
190    }
191    means that you added ``myOwnBottomDragCoefficient'' to a namelist at
192    the same time and place that we added ``bottomDragQuadratic''. You
193    need to resolve this conflict and in this case the line should be
194    changed to:
195    {\small
196    \begin{verbatim}
197         & bottomDragLinear,bottomDragQuadratic,myOwnBottomDragCoefficient,
198    \end{verbatim}
199    }
200    and the lines with the delimiters ($<<<<<<$,======,$>>>>>>$) be deleted.
201    Unless you are making modifications which exactly parallel
202    developments we make, these types of conflicts should be rare.
203    
204    \paragraph*{Upgrading to the current pre-release version}
205    
206    We don't make a ``release'' for every little patch and bug fix in
207    order to keep the frequency of upgrades to a minimum. However, if you
208    have run into a problem for which ``we have already fixed in the
209    latest code'' and we haven't made a ``tag'' or ``release'' since that
210    patch then you'll need to get the latest code:
211    \begin{verbatim}
212    % cvs -q update -A -d -P
213    \end{verbatim}
214    Unlike, the ``check-out'' and ``update'' procedures above, there is no
215    ``tag'' or release name. The -A tells CVS to upgrade to the
216    very latest version. As a rule, we don't recommend this since you
217    might upgrade while we are in the processes of checking in the code so
218    that you may only have part of a patch. Using this method of updating
219    also means we can't tell what version of the code you are working
220    with. So please be sure you understand what you're doing.
221    
222  \paragraph*{Conventional download method}  \subsection{Method 2 - Tar file download}
223  \label{sect:conventionalDownload}  \label{sect:conventionalDownload}
224    
225  If you do not have CVS on your system, you can download the model as a  If you do not have CVS on your system, you can download the model as a
226  tar file from the reference web site at:  tar file from the web site at:
227    \begin{rawhtml} <A href=http://mitgcm.org/download/ target="idontexist"> \end{rawhtml}
228  \begin{verbatim}  \begin{verbatim}
229  http://mitgcm.org/download/  http://mitgcm.org/download/
230  \end{verbatim}  \end{verbatim}
231    \begin{rawhtml} </A> \end{rawhtml}
232  The tar file still contains CVS information which we urge you not to  The tar file still contains CVS information which we urge you not to
233  delete; even if you do not use CVS yourself the information can help  delete; even if you do not use CVS yourself the information can help
234  us if you should need to send us your copy of the code.  us if you should need to send us your copy of the code.  If a recent
235    tar file does not exist, then please contact the developers through
236    the
237    \begin{rawhtml} <A href="mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
238    MITgcm-support@mitgcm.org
239    \begin{rawhtml} </A> \end{rawhtml}
240    mailing list.
241    
242  \section{Model and directory structure}  \section{Model and directory structure}
243    \begin{rawhtml}
244  The ``numerical'' model is contained within a execution environment support  <!-- CMIREDIR:directory_structure: -->
245  wrapper. This wrapper is designed to provide a general framework for  \end{rawhtml}
246  grid-point models. MITgcmUV is a specific numerical model that uses the  
247  framework. Under this structure the model is split into execution  The ``numerical'' model is contained within a execution environment
248  environment support code and conventional numerical model code. The  support wrapper. This wrapper is designed to provide a general
249  execution environment support code is held under the \textit{eesupp}  framework for grid-point models. MITgcmUV is a specific numerical
250  directory. The grid point model code is held under the \textit{model}  model that uses the framework. Under this structure the model is split
251  directory. Code execution actually starts in the \textit{eesupp} routines  into execution environment support code and conventional numerical
252  and not in the \textit{model} routines. For this reason the top-level  model code. The execution environment support code is held under the
253  \textit{MAIN.F} is in the \textit{eesupp/src} directory. In general,  \texttt{eesupp} directory. The grid point model code is held under the
254  end-users should not need to worry about this level. The top-level routine  \texttt{model} directory. Code execution actually starts in the
255  for the numerical part of the code is in \textit{model/src/THE\_MODEL\_MAIN.F%  \texttt{eesupp} routines and not in the \texttt{model} routines. For
256  }. Here is a brief description of the directory structure of the model under  this reason the top-level \texttt{MAIN.F} is in the
257  the root tree (a detailed description is given in section 3: Code structure).  \texttt{eesupp/src} directory. In general, end-users should not need
258    to worry about this level. The top-level routine for the numerical
259  \begin{itemize}  part of the code is in \texttt{model/src/THE\_MODEL\_MAIN.F}. Here is
260  \item \textit{bin}: this directory is initially empty. It is the default  a brief description of the directory structure of the model under the
261  directory in which to compile the code.  root tree (a detailed description is given in section 3: Code
262    structure).
263  \item \textit{diags}: contains the code relative to time-averaged  
264  diagnostics. It is subdivided into two subdirectories \textit{inc} and  \begin{itemize}
265  \textit{src} that contain include files (*.\textit{h} files) and fortran  
266  subroutines (*.\textit{F} files), respectively.  \item \texttt{doc}: contains brief documentation notes.
267      
268  \item \textit{doc}: contains brief documentation notes.  \item \texttt{eesupp}: contains the execution environment source code.
269      Also subdivided into two subdirectories \texttt{inc} and
270  \item \textit{eesupp}: contains the execution environment source code. Also    \texttt{src}.
271  subdivided into two subdirectories \textit{inc} and \textit{src}.    
272    \item \texttt{model}: this directory contains the main source code.
273  \item \textit{exe}: this directory is initially empty. It is the default    Also subdivided into two subdirectories \texttt{inc} and
274  directory in which to execute the code.    \texttt{src}.
275      
276  \item \textit{model}: this directory contains the main source code. Also  \item \texttt{pkg}: contains the source code for the packages. Each
277  subdivided into two subdirectories \textit{inc} and \textit{src}.    package corresponds to a subdirectory. For example, \texttt{gmredi}
278      contains the code related to the Gent-McWilliams/Redi scheme,
279  \item \textit{pkg}: contains the source code for the packages. Each package    \texttt{aim} the code relative to the atmospheric intermediate
280  corresponds to a subdirectory. For example, \textit{gmredi} contains the    physics. The packages are described in detail in chapter \ref{chap.packagesI}.
281  code related to the Gent-McWilliams/Redi scheme, \textit{aim} the code    
282  relative to the atmospheric intermediate physics. The packages are described  \item \texttt{tools}: this directory contains various useful tools.
283  in detail in section 3.    For example, \texttt{genmake2} is a script written in csh (C-shell)
284      that should be used to generate your makefile. The directory
285  \item \textit{tools}: this directory contains various useful tools. For    \texttt{adjoint} contains the makefile specific to the Tangent
286  example, \textit{genmake} is a script written in csh (C-shell) that should    linear and Adjoint Compiler (TAMC) that generates the adjoint code.
287  be used to generate your makefile. The directory \textit{adjoint} contains    The latter is described in detail in part \ref{chap.ecco}.
288  the makefile specific to the Tangent linear and Adjoint Compiler (TAMC) that    This directory also contains the subdirectory build\_options, which
289  generates the adjoint code. The latter is described in details in part V.    contains the `optfiles' with the compiler options for the different
290      compilers and machines that can run MITgcm.
291  \item \textit{utils}: this directory contains various utilities. The    
292  subdirectory \textit{knudsen2} contains code and a makefile that  \item \texttt{utils}: this directory contains various utilities. The
293  compute coefficients of the polynomial approximation to the knudsen    subdirectory \texttt{knudsen2} contains code and a makefile that
294  formula for an ocean nonlinear equation of state. The \textit{matlab}    compute coefficients of the polynomial approximation to the knudsen
295  subdirectory contains matlab scripts for reading model output directly    formula for an ocean nonlinear equation of state. The
296  into matlab. \textit{scripts} contains C-shell post-processing    \texttt{matlab} subdirectory contains matlab scripts for reading
297  scripts for joining processor-based and tiled-based model output.    model output directly into matlab. \texttt{scripts} contains C-shell
298      post-processing scripts for joining processor-based and tiled-based
299  \item \textit{verification}: this directory contains the model examples. See    model output. The subdirectory exch2 contains the code needed for
300  section \ref{sect:modelExamples}.    the exch2 package to work with different combinations of domain
301  \end{itemize}    decompositions.
302      
303  \section{Example experiments}  \item \texttt{verification}: this directory contains the model
304  \label{sect:modelExamples}    examples. See section \ref{sect:modelExamples}.
305    
306  Now that you have successfully downloaded the model code we recommend that  \item \texttt{jobs}: contains sample job scripts for running MITgcm.
307  you first try to run the examples provided with the base version. You will    
308  probably want to run the example that is the closest to the configuration  \item \texttt{lsopt}: Line search code used for optimization.
309  you will use eventually. The examples are located in subdirectories under    
310  the directory \textit{verification} and are briefly described below (a full  \item \texttt{optim}: Interface between MITgcm and line search code.
311  description is given in section 2):    
   
 \subsection{List of model examples}  
   
 \begin{itemize}  
 \item \textit{exp0} - single layer, ocean double gyre (barotropic with  
 free-surface).  
   
 \item \textit{exp1} - 4 layers, ocean double gyre.  
   
 \item \textit{exp2} - 4x4 degree global ocean simulation with steady  
 climatological forcing.  
   
 \item \textit{exp4} - flow over a Gaussian bump in open-water or channel  
 with open boundaries.  
   
 \item \textit{exp5} - inhomogenously forced ocean convection in a doubly  
 periodic box.  
   
 \item \textit{front\_relax} - relaxation of an ocean thermal front (test for  
 Gent/McWilliams scheme). 2D (Y-Z).  
   
 \item \textit{internal wave} - ocean internal wave forced by open boundary  
 conditions.  
   
 \item \textit{natl\_box} - eastern subtropical North Atlantic with KPP  
 scheme; 1 month integration  
   
 \item \textit{hs94.1x64x5} - zonal averaged atmosphere using Held and Suarez  
 '94 forcing.  
   
 \item \textit{hs94.128x64x5} - 3D atmosphere dynamics using Held and Suarez  
 '94 forcing.  
   
 \item \textit{hs94.cs-32x32x5} - 3D atmosphere dynamics using Held and  
 Suarez '94 forcing on the cubed sphere.  
   
 \item \textit{aim.5l\_zon-ave} - Intermediate Atmospheric physics, 5 layers  
 Molteni physics package. Global Zonal Mean configuration, 1x64x5 resolution.  
   
 \item \textit{aim.5l\_XZ\_Equatorial\_Slice} - Intermediate Atmospheric  
 physics, 5 layers Molteni physics package. Equatorial Slice configuration.  
 2D (X-Z).  
   
 \item \textit{aim.5l\_Equatorial\_Channel} - Intermediate Atmospheric  
 physics, 5 layers Molteni physics package. 3D Equatorial Channel  
 configuration (not completely tested).  
   
 \item \textit{aim.5l\_LatLon} - Intermediate Atmospheric physics, 5 layers  
 Molteni physics package. Global configuration, 128x64x5 resolution.  
   
 \item \textit{adjustment.128x64x1}  
   
 \item \textit{adjustment.cs-32x32x1}  
312  \end{itemize}  \end{itemize}
313    
314  \subsection{Directory structure of model examples}  \section[Building MITgcm]{Building the code}
   
 Each example directory has the following subdirectories:  
   
 \begin{itemize}  
 \item \textit{code}: contains the code particular to the example. At a  
 minimum, this directory includes the following files:  
   
 \begin{itemize}  
 \item \textit{code/CPP\_EEOPTIONS.h}: declares CPP keys relative to the  
 ``execution environment'' part of the code. The default version is located  
 in \textit{eesupp/inc}.  
   
 \item \textit{code/CPP\_OPTIONS.h}: declares CPP keys relative to the  
 ``numerical model'' part of the code. The default version is located in  
 \textit{model/inc}.  
   
 \item \textit{code/SIZE.h}: declares size of underlying computational grid.  
 The default version is located in \textit{model/inc}.  
 \end{itemize}  
   
 In addition, other include files and subroutines might be present in \textit{%  
 code} depending on the particular experiment. See section 2 for more details.  
   
 \item \textit{input}: contains the input data files required to run the  
 example. At a mimimum, the \textit{input} directory contains the following  
 files:  
   
 \begin{itemize}  
 \item \textit{input/data}: this file, written as a namelist, specifies the  
 main parameters for the experiment.  
   
 \item \textit{input/data.pkg}: contains parameters relative to the packages  
 used in the experiment.  
   
 \item \textit{input/eedata}: this file contains ``execution environment''  
 data. At present, this consists of a specification of the number of threads  
 to use in $X$ and $Y$ under multithreaded execution.  
 \end{itemize}  
   
 In addition, you will also find in this directory the forcing and topography  
 files as well as the files describing the initial state of the experiment.  
 This varies from experiment to experiment. See section 2 for more details.  
   
 \item \textit{results}: this directory contains the output file \textit{%  
 output.txt} produced by the simulation example. This file is useful for  
 comparison with your own output when you run the experiment.  
 \end{itemize}  
   
 Once you have chosen the example you want to run, you are ready to compile  
 the code.  
   
 \section{Building the code}  
315  \label{sect:buildingCode}  \label{sect:buildingCode}
316    \begin{rawhtml}
317    <!-- CMIREDIR:buildingCode: -->
318    \end{rawhtml}
319    
320    To compile the code, we use the \texttt{make} program. This uses a
321    file (\texttt{Makefile}) that allows us to pre-process source files,
322    specify compiler and optimization options and also figures out any
323    file dependencies. We supply a script (\texttt{genmake2}), described
324    in section \ref{sect:genmake}, that automatically creates the
325    \texttt{Makefile} for you. You then need to build the dependencies and
326    compile the code.
327    
328    As an example, assume that you want to build and run experiment
329    \texttt{verification/exp2}. The are multiple ways and places to
330    actually do this but here let's build the code in
331    \texttt{verification/exp2/build}:
332    \begin{verbatim}
333    % cd verification/exp2/build
334    \end{verbatim}
335    First, build the \texttt{Makefile}:
336    \begin{verbatim}
337    % ../../../tools/genmake2 -mods=../code
338    \end{verbatim}
339    The command line option tells \texttt{genmake} to override model source
340    code with any files in the directory \texttt{../code/}.
341    
342    On many systems, the \texttt{genmake2} program will be able to
343    automatically recognize the hardware, find compilers and other tools
344    within the user's path (``\texttt{echo \$PATH}''), and then choose an
345    appropriate set of options from the files (``optfiles'') contained in
346    the \texttt{tools/build\_options} directory.  Under some
347    circumstances, a user may have to create a new ``optfile'' in order to
348    specify the exact combination of compiler, compiler flags, libraries,
349    and other options necessary to build a particular configuration of
350    MITgcm.  In such cases, it is generally helpful to read the existing
351    ``optfiles'' and mimic their syntax.
352    
353    Through the MITgcm-support list, the MITgcm developers are willing to
354    provide help writing or modifing ``optfiles''.  And we encourage users
355    to post new ``optfiles'' (particularly ones for new machines or
356    architectures) to the
357    \begin{rawhtml} <A href="mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
358    MITgcm-support@mitgcm.org
359    \begin{rawhtml} </A> \end{rawhtml}
360    list.
361    
362  To compile the code, we use the {\em make} program. This uses a file  To specify an optfile to \texttt{genmake2}, the syntax is:
 ({\em Makefile}) that allows us to pre-process source files, specify  
 compiler and optimization options and also figures out any file  
 dependancies. We supply a script ({\em genmake}), described in section  
 \ref{sect:genmake}, that automatically creates the {\em Makefile} for  
 you. You then need to build the dependancies and compile the code.  
   
 As an example, let's assume that you want to build and run experiment  
 \textit{verification/exp2}. The are multiple ways and places to actually  
 do this but here let's build the code in  
 \textit{verification/exp2/input}:  
 \begin{verbatim}  
 % cd verification/exp2/input  
 \end{verbatim}  
 First, build the {\em Makefile}:  
363  \begin{verbatim}  \begin{verbatim}
364  % ../../../tools/genmake -mods=../code  % ../../../tools/genmake2 -mods=../code -of /path/to/optfile
365  \end{verbatim}  \end{verbatim}
 The command line option tells {\em genmake} to override model source  
 code with any files in the directory {\em ./code/}.  
366    
367  If there is no \textit{.genmakerc} in the \textit{input} directory, you have  Once a \texttt{Makefile} has been generated, we create the
368  to use the following options when invoking \textit{genmake}:  dependencies with the command:
 \begin{verbatim}  
 % ../../../tools/genmake  -mods=../code  
 \end{verbatim}  
   
 Next, create the dependancies:  
369  \begin{verbatim}  \begin{verbatim}
370  % make depend  % make depend
371  \end{verbatim}  \end{verbatim}
372  This modifies {\em Makefile} by attaching a [long] list of files on  This modifies the \texttt{Makefile} by attaching a (usually, long)
373  which other files depend. The purpose of this is to reduce  list of files upon which other files depend. The purpose of this is to
374  re-compilation if and when you start to modify the code. {\tt make  reduce re-compilation if and when you start to modify the code. The
375  depend} also created links from the model source to this directory.  {\tt make depend} command also creates links from the model source to
376    this directory.  It is important to note that the {\tt make depend}
377    stage will occasionally produce warnings or errors since the
378    dependency parsing tool is unable to find all of the necessary header
379    files (\textit{eg.}  \texttt{netcdf.inc}).  In these circumstances, it
380    is usually OK to ignore the warnings/errors and proceed to the next
381    step.
382    
383  Now compile the code:  Next one can compile the code using:
384  \begin{verbatim}  \begin{verbatim}
385  % make  % make
386  \end{verbatim}  \end{verbatim}
387  The {\tt make} command creates an executable called \textit{mitgcmuv}.  The {\tt make} command creates an executable called \texttt{mitgcmuv}.
388    Additional make ``targets'' are defined within the makefile to aid in
389    the production of adjoint and other versions of MITgcm.  On SMP
390    (shared multi-processor) systems, the build process can often be sped
391    up appreciably using the command:
392    \begin{verbatim}
393    % make -j 2
394    \end{verbatim}
395    where the ``2'' can be replaced with a number that corresponds to the
396    number of CPUs available.
397    
398  Now you are ready to run the model. General instructions for doing so are  Now you are ready to run the model. General instructions for doing so are
399  given in section \ref{sect:runModel}. Here, we can run the model with:  given in section \ref{sect:runModel}. Here, we can run the model by
400    first creating links to all the input files:
401    \begin{verbatim}
402    ln -s ../input/* .
403    \end{verbatim}
404    and then calling the executable with:
405  \begin{verbatim}  \begin{verbatim}
406  ./mitgcmuv > output.txt  ./mitgcmuv > output.txt
407  \end{verbatim}  \end{verbatim}
408  where we are re-directing the stream of text output to the file {\em  where we are re-directing the stream of text output to the file
409  output.txt}.  \texttt{output.txt}.
   
410    
411  \subsection{Building/compiling the code elsewhere}  \subsection{Building/compiling the code elsewhere}
412    
# Line 326  executable in the {\em input} directory Line 415  executable in the {\em input} directory
415  convenience. You can also configure and compile the code in other  convenience. You can also configure and compile the code in other
416  locations, for example on a scratch disk with out having to copy the  locations, for example on a scratch disk with out having to copy the
417  entire source tree. The only requirement to do so is you have {\tt  entire source tree. The only requirement to do so is you have {\tt
418  genmake} in your path or you know the absolute path to {\tt genmake}.    genmake2} in your path or you know the absolute path to {\tt
419      genmake2}.
420    
421  The following sections outline some possible methods of organizing you  The following sections outline some possible methods of organizing
422  source and data.  your source and data.
423    
424  \subsubsection{Building from the {\em ../code directory}}  \subsubsection{Building from the {\em ../code directory}}
425    
426  This is just as simple as building in the {\em input/} directory:  This is just as simple as building in the {\em input/} directory:
427  \begin{verbatim}  \begin{verbatim}
428  % cd verification/exp2/code  % cd verification/exp2/code
429  % ../../../tools/genmake  % ../../../tools/genmake2
430  % make depend  % make depend
431  % make  % make
432  \end{verbatim}  \end{verbatim}
# Line 347  files must be in the same place. If you Line 437  files must be in the same place. If you
437  % cp ../code/mitgcmuv ./  % cp ../code/mitgcmuv ./
438  % ./mitgcmuv > output.txt  % ./mitgcmuv > output.txt
439  \end{verbatim}  \end{verbatim}
440  or if you will be making muliple runs with the same executable:  or if you will be making multiple runs with the same executable:
441  \begin{verbatim}  \begin{verbatim}
442  % cd ../  % cd ../
443  % cp -r input run1  % cp -r input run1
# Line 359  or if you will be making muliple runs wi Line 449  or if you will be making muliple runs wi
449  \subsubsection{Building from a new directory}  \subsubsection{Building from a new directory}
450    
451  Since the {\em input} directory contains input files it is often more  Since the {\em input} directory contains input files it is often more
452  useful to keep {\em input} prestine and build in a new directory  useful to keep {\em input} pristine and build in a new directory
453  within {\em verification/exp2/}:  within {\em verification/exp2/}:
454  \begin{verbatim}  \begin{verbatim}
455  % cd verification/exp2  % cd verification/exp2
456  % mkdir build  % mkdir build
457  % cd build  % cd build
458  % ../../../tools/genmake -mods=../code  % ../../../tools/genmake2 -mods=../code
459  % make depend  % make depend
460  % make  % make
461  \end{verbatim}  \end{verbatim}
# Line 387  running in a new directory each time mig Line 477  running in a new directory each time mig
477  % ./mitgcmuv > output.txt  % ./mitgcmuv > output.txt
478  \end{verbatim}  \end{verbatim}
479    
480  \subsubsection{Building from on a scratch disk}  \subsubsection{Building on a scratch disk}
481    
482  Model object files and output data can use up large amounts of disk  Model object files and output data can use up large amounts of disk
483  space so it is often the case that you will be operating on a large  space so it is often the case that you will be operating on a large
# Line 395  scratch disk. Assuming the model source Line 485  scratch disk. Assuming the model source
485  following commands will build the model in {\em /scratch/exp2-run1}:  following commands will build the model in {\em /scratch/exp2-run1}:
486  \begin{verbatim}  \begin{verbatim}
487  % cd /scratch/exp2-run1  % cd /scratch/exp2-run1
488  % ~/MITgcm/tools/genmake -rootdir=~/MITgcm -mods=~/MITgcm/verification/exp2/code  % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
489      -mods=~/MITgcm/verification/exp2/code
490  % make depend  % make depend
491  % make  % make
492  \end{verbatim}  \end{verbatim}
# Line 411  the one experiment: Line 502  the one experiment:
502  % cd /scratch/exp2  % cd /scratch/exp2
503  % mkdir build  % mkdir build
504  % cd build  % cd build
505  % ~/MITgcm/tools/genmake -rootdir=~/MITgcm -mods=~/MITgcm/verification/exp2/code  % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
506      -mods=~/MITgcm/verification/exp2/code
507  % make depend  % make depend
508  % make  % make
509  % cd ../  % cd ../
# Line 421  the one experiment: Line 513  the one experiment:
513  \end{verbatim}  \end{verbatim}
514    
515    
516    \subsection{Using \texttt{genmake2}}
 \subsection{\textit{genmake}}  
517  \label{sect:genmake}  \label{sect:genmake}
518    
519  To compile the code, use the script \textit{genmake} located in the \textit{%  To compile the code, first use the program \texttt{genmake2} (located
520  tools} directory. \textit{genmake} is a script that generates the makefile.  in the \texttt{tools} directory) to generate a Makefile.
521  It has been written so that the code can be compiled on a wide diversity of  \texttt{genmake2} is a shell script written to work with all
522  machines and systems. However, if it doesn't work the first time on your  ``sh''--compatible shells including bash v1, bash v2, and Bourne.
523  platform, you might need to edit certain lines of \textit{genmake} in the  Internally, \texttt{genmake2} determines the locations of needed
524  section containing the setups for the different machines. The file is  files, the compiler, compiler options, libraries, and Unix tools.  It
525  structured like this:  relies upon a number of ``optfiles'' located in the
526  \begin{verbatim}  \texttt{tools/build\_options} directory.
527          .  
528          .  The purpose of the optfiles is to provide all the compilation options
529          .  for particular ``platforms'' (where ``platform'' roughly means the
530  general instructions (machine independent)  combination of the hardware and the compiler) and code configurations.
531          .  Given the combinations of possible compilers and library dependencies
532          .  ({\it eg.}  MPI and NetCDF) there may be numerous optfiles available
533          .  for a single machine.  The naming scheme for the majority of the
534      - setup machine 1  optfiles shipped with the code is
535      - setup machine 2  \begin{center}
536      - setup machine 3    {\bf OS\_HARDWARE\_COMPILER }
537      - setup machine 4  \end{center}
538         etc  where
539          .  \begin{description}
540          .  \item[OS] is the name of the operating system (generally the
541          .    lower-case output of the {\tt 'uname'} command)
542  \end{verbatim}  \item[HARDWARE] is a string that describes the CPU type and
543      corresponds to output from the  {\tt 'uname -m'} command:
544  For example, the setup corresponding to a DEC alpha machine is reproduced    \begin{description}
545  here:    \item[ia32] is for ``x86'' machines such as i386, i486, i586, i686,
546  \begin{verbatim}      and athlon
547    case OSF1+mpi:    \item[ia64] is for Intel IA64 systems (eg. Itanium, Itanium2)
548      echo "Configuring for DEC Alpha"    \item[amd64] is AMD x86\_64 systems
549      set CPP        = ( '/usr/bin/cpp -P' )    \item[ppc] is for Mac PowerPC systems
550      set DEFINES    = ( ${DEFINES}  '-DTARGET_DEC -DWORDLENGTH=1' )    \end{description}
551      set KPP        = ( 'kapf' )  \item[COMPILER] is the compiler name (generally, the name of the
552      set KPPFILES   = ( 'main.F' )    FORTRAN executable)
553      set KFLAGS1    = ( '-scan=132 -noconc -cmp=' )  \end{description}
554      set FC         = ( 'f77' )  
555      set FFLAGS     = ( '-convert big_endian -r8 -extend_source -automatic -call_shared -notransform_loops -align dcommons' )  In many cases, the default optfiles are sufficient and will result in
556      set FOPTIM     = ( '-O5 -fast -tune host -inline all' )  usable Makefiles.  However, for some machines or code configurations,
557      set NOOPTFLAGS = ( '-O0' )  new ``optfiles'' must be written. To create a new optfile, it is
558      set LIBS       = ( '-lfmpi -lmpi -lkmp_osfp10 -pthread' )  generally best to start with one of the defaults and modify it to suit
559      set NOOPTFILES = ( 'barrier.F different_multiple.F external_fields_load.F')  your needs.  Like \texttt{genmake2}, the optfiles are all written
560      set RMFILES    = ( '*.p.out' )  using a simple ``sh''--compatible syntax.  While nearly all variables
561      breaksw  used within \texttt{genmake2} may be specified in the optfiles, the
562  \end{verbatim}  critical ones that should be defined are:
563    
564  Typically, these are the lines that you might need to edit to make \textit{%  \begin{description}
565  genmake} work on your platform if it doesn't work the first time. \textit{%  \item[FC] the FORTRAN compiler (executable) to use
566  genmake} understands several options that are described here:  \item[DEFINES] the command-line DEFINE options passed to the compiler
567    \item[CPP] the C pre-processor to use
568  \begin{itemize}  \item[NOOPTFLAGS] options flags for special files that should not be
569  \item -rootdir=dir    optimized
570    \end{description}
571  indicates where the model root directory is relative to the directory where  
572  you are compiling. This option is not needed if you compile in the \textit{%  For example, the optfile for a typical Red Hat Linux machine (``ia32''
573  bin} directory (which is the default compilation directory) or within the  architecture) using the GCC (g77) compiler is
574  \textit{verification} tree.  \begin{verbatim}
575    FC=g77
576  \item -mods=dir1,dir2,...  DEFINES='-D_BYTESWAPIO -DWORDLENGTH=4'
577    CPP='cpp  -traditional -P'
578  indicates the relative or absolute paths directories where the sources  NOOPTFLAGS='-O0'
579  should take precedence over the default versions (located in \textit{model},  #  For IEEE, use the "-ffloat-store" option
580  \textit{eesupp},...). Typically, this option is used when running the  if test "x$IEEE" = x ; then
581  examples, see below.      FFLAGS='-Wimplicit -Wunused -Wuninitialized'
582        FOPTIM='-O3 -malign-double -funroll-loops'
583  \item -enable=pkg1,pkg2,...  else
584        FFLAGS='-Wimplicit -Wunused -ffloat-store'
585  enables packages source code \textit{pkg1}, \textit{pkg2},... when creating      FOPTIM='-O0 -malign-double'
586  the makefile.  fi
587    \end{verbatim}
588  \item -disable=pkg1,pkg2,...  
589    If you write an optfile for an unrepresented machine or compiler, you
590  disables packages source code \textit{pkg1}, \textit{pkg2},... when creating  are strongly encouraged to submit the optfile to the MITgcm project
591  the makefile.  for inclusion.  Please send the file to the
592    \begin{rawhtml} <A href="mail-to:MITgcm-support@mitgcm.org"> \end{rawhtml}
593  \item -platform=machine  \begin{center}
594      MITgcm-support@mitgcm.org
595    \end{center}
596    \begin{rawhtml} </A> \end{rawhtml}
597    mailing list.
598    
599    In addition to the optfiles, \texttt{genmake2} supports a number of
600    helpful command-line options.  A complete list of these options can be
601    obtained from:
602    \begin{verbatim}
603    % genmake2 -h
604    \end{verbatim}
605    
606    The most important command-line options are:
607    \begin{description}
608      
609    \item[\texttt{--optfile=/PATH/FILENAME}] specifies the optfile that
610      should be used for a particular build.
611      
612      If no "optfile" is specified (either through the command line or the
613      MITGCM\_OPTFILE environment variable), genmake2 will try to make a
614      reasonable guess from the list provided in {\em
615        tools/build\_options}.  The method used for making this guess is
616      to first determine the combination of operating system and hardware
617      (eg. "linux\_ia32") and then find a working FORTRAN compiler within
618      the user's path.  When these three items have been identified,
619      genmake2 will try to find an optfile that has a matching name.
620      
621    \item[\texttt{--pdefault='PKG1 PKG2 PKG3 ...'}] specifies the default
622      set of packages to be used.  The normal order of precedence for
623      packages is as follows:
624      \begin{enumerate}
625      \item If available, the command line (\texttt{--pdefault}) settings
626        over-rule any others.
627    
628      \item Next, \texttt{genmake2} will look for a file named
629        ``\texttt{packages.conf}'' in the local directory or in any of the
630        directories specified with the \texttt{--mods} option.
631        
632      \item Finally, if neither of the above are available,
633        \texttt{genmake2} will use the \texttt{/pkg/pkg\_default} file.
634      \end{enumerate}
635      
636    \item[\texttt{--pdepend=/PATH/FILENAME}] specifies the dependency file
637      used for packages.
638      
639      If not specified, the default dependency file {\em pkg/pkg\_depend}
640      is used.  The syntax for this file is parsed on a line-by-line basis
641      where each line containes either a comment ("\#") or a simple
642      "PKGNAME1 (+|-)PKGNAME2" pairwise rule where the "+" or "-" symbol
643      specifies a "must be used with" or a "must not be used with"
644      relationship, respectively.  If no rule is specified, then it is
645      assumed that the two packages are compatible and will function
646      either with or without each other.
647      
648    \item[\texttt{--adof=/path/to/file}] specifies the "adjoint" or
649      automatic differentiation options file to be used.  The file is
650      analogous to the ``optfile'' defined above but it specifies
651      information for the AD build process.
652      
653      The default file is located in {\em
654        tools/adjoint\_options/adjoint\_default} and it defines the "TAF"
655      and "TAMC" compilers.  An alternate version is also available at
656      {\em tools/adjoint\_options/adjoint\_staf} that selects the newer
657      "STAF" compiler.  As with any compilers, it is helpful to have their
658      directories listed in your {\tt \$PATH} environment variable.
659      
660    \item[\texttt{--mods='DIR1 DIR2 DIR3 ...'}] specifies a list of
661      directories containing ``modifications''.  These directories contain
662      files with names that may (or may not) exist in the main MITgcm
663      source tree but will be overridden by any identically-named sources
664      within the ``MODS'' directories.
665      
666      The order of precedence for this "name-hiding" is as follows:
667      \begin{itemize}
668      \item ``MODS'' directories (in the order given)
669      \item Packages either explicitly specified or provided by default
670        (in the order given)
671      \item Packages included due to package dependencies (in the order
672        that that package dependencies are parsed)
673      \item The "standard dirs" (which may have been specified by the
674        ``-standarddirs'' option)
675      \end{itemize}
676      
677    \item[\texttt{--mpi}] This option enables certain MPI features (using
678      CPP \texttt{\#define}s) within the code and is necessary for MPI
679      builds (see Section \ref{sect:mpi-build}).
680      
681    \item[\texttt{--make=/path/to/gmake}] Due to the poor handling of
682      soft-links and other bugs common with the \texttt{make} versions
683      provided by commercial Unix vendors, GNU \texttt{make} (sometimes
684      called \texttt{gmake}) should be preferred.  This option provides a
685      means for specifying the make executable to be used.
686      
687    \item[\texttt{--bash=/path/to/sh}] On some (usually older UNIX)
688      machines, the ``bash'' shell is unavailable.  To run on these
689      systems, \texttt{genmake2} can be invoked using an ``sh'' (that is,
690      a Bourne, POSIX, or compatible) shell.  The syntax in these
691      circumstances is:
692      \begin{center}
693        \texttt{\%  /bin/sh genmake2 -bash=/bin/sh [...options...]}
694      \end{center}
695      where \texttt{/bin/sh} can be replaced with the full path and name
696      of the desired shell.
697    
698    \end{description}
699    
700    
701    \subsection{Building with MPI}
702    \label{sect:mpi-build}
703    
704    Building MITgcm to use MPI libraries can be complicated due to the
705    variety of different MPI implementations available, their dependencies
706    or interactions with different compilers, and their often ad-hoc
707    locations within file systems.  For these reasons, its generally a
708    good idea to start by finding and reading the documentation for your
709    machine(s) and, if necessary, seeking help from your local systems
710    administrator.
711    
712    The steps for building MITgcm with MPI support are:
713    \begin{enumerate}
714      
715    \item Determine the locations of your MPI-enabled compiler and/or MPI
716      libraries and put them into an options file as described in Section
717      \ref{sect:genmake}.  One can start with one of the examples in:
718      \begin{rawhtml} <A
719        href="http://mitgcm.org/viewvc/MITgcm/MITgcm/tools/build_options/">
720      \end{rawhtml}
721      \begin{center}
722        \texttt{MITgcm/tools/build\_options/}
723      \end{center}
724      \begin{rawhtml} </A> \end{rawhtml}
725      such as \texttt{linux\_ia32\_g77+mpi\_cg01} or
726      \texttt{linux\_ia64\_efc+mpi} and then edit it to suit the machine at
727      hand.  You may need help from your user guide or local systems
728      administrator to determine the exact location of the MPI libraries.
729      If libraries are not installed, MPI implementations and related
730      tools are available including:
731      \begin{itemize}
732      \item \begin{rawhtml} <A
733          href="http://www-unix.mcs.anl.gov/mpi/mpich/">
734        \end{rawhtml}
735        MPICH
736        \begin{rawhtml} </A> \end{rawhtml}
737    
738      \item \begin{rawhtml} <A
739          href="http://www.lam-mpi.org/">
740        \end{rawhtml}
741        LAM/MPI
742        \begin{rawhtml} </A> \end{rawhtml}
743    
744      \item \begin{rawhtml} <A
745          href="http://www.osc.edu/~pw/mpiexec/">
746        \end{rawhtml}
747        MPIexec
748        \begin{rawhtml} </A> \end{rawhtml}
749      \end{itemize}
750      
751    \item Build the code with the \texttt{genmake2} \texttt{-mpi} option
752      (see Section \ref{sect:genmake}) using commands such as:
753    {\footnotesize \begin{verbatim}
754      %  ../../../tools/genmake2 -mods=../code -mpi -of=YOUR_OPTFILE
755      %  make depend
756      %  make
757    \end{verbatim} }
758      
759    \item Run the code with the appropriate MPI ``run'' or ``exec''
760      program provided with your particular implementation of MPI.
761      Typical MPI packages such as MPICH will use something like:
762    \begin{verbatim}
763      %  mpirun -np 4 -machinefile mf ./mitgcmuv
764    \end{verbatim}
765      Sightly more complicated scripts may be needed for many machines
766      since execution of the code may be controlled by both the MPI
767      library and a job scheduling and queueing system such as PBS,
768      LoadLeveller, Condor, or any of a number of similar tools.  A few
769      example scripts (those used for our \begin{rawhtml} <A
770        href="http://mitgcm.org/public/testing.html"> \end{rawhtml}regular
771      verification runs\begin{rawhtml} </A> \end{rawhtml}) are available
772      at:
773      \begin{rawhtml} <A
774        href="http://mitgcm.org/viewvc/MITgcm/MITgcm/tools/example_scripts/">
775      \end{rawhtml}
776      {\footnotesize \tt
777        http://mitgcm.org/viewvc/MITgcm/MITgcm/tools/example\_scripts/ }
778      \begin{rawhtml} </A> \end{rawhtml}
779      or at:
780      \begin{rawhtml} <A
781        href="http://mitgcm.org/viewvc/MITgcm/MITgcm_contrib/test_scripts/">
782      \end{rawhtml}
783      {\footnotesize \tt
784        http://mitgcm.org/viewvc/MITgcm/MITgcm\_contrib/test\_scripts/ }
785      \begin{rawhtml} </A> \end{rawhtml}
786    
787    \end{enumerate}
788    
789    An example of the above process on the MITgcm cluster (``cg01'') using
790    the GNU g77 compiler and the mpich MPI library is:
791    
792    {\footnotesize \begin{verbatim}
793      %  cd MITgcm/verification/exp5
794      %  mkdir build
795      %  cd build
796      %  ../../../tools/genmake2 -mpi -mods=../code \
797           -of=../../../tools/build_options/linux_ia32_g77+mpi_cg01
798      %  make depend
799      %  make
800      %  cd ../input
801      %  /usr/local/pkg/mpi/mpi-1.2.4..8a-gm-1.5/g77/bin/mpirun.ch_gm \
802           -machinefile mf --gm-kill 5 -v -np 2  ../build/mitgcmuv
803    \end{verbatim} }
804    
805  specifies the platform for which you want the makefile. In general, you  \section[Running MITgcm]{Running the model in prognostic mode}
 won't need this option. \textit{genmake} will select the right machine for  
 you (the one you're working on!). However, this option is useful if you have  
 a choice of several compilers on one machine and you want to use the one  
 that is not the default (ex: \texttt{pgf77} instead of \texttt{f77} under  
 Linux).  
   
 \item -mpi  
   
 this is used when you want to run the model in parallel processing mode  
 under mpi (see section on parallel computation for more details).  
   
 \item -jam  
   
 this is used when you want to run the model in parallel processing mode  
 under jam (see section on parallel computation for more details).  
 \end{itemize}  
   
 For some of the examples, there is a file called \textit{.genmakerc} in the  
 \textit{input} directory that has the relevant \textit{genmake} options for  
 that particular example. In this way you don't need to type the options when  
 invoking \textit{genmake}.  
   
   
 \section{Running the model}  
806  \label{sect:runModel}  \label{sect:runModel}
807    \begin{rawhtml}
808    <!-- CMIREDIR:runModel: -->
809    \end{rawhtml}
810    
811    If compilation finished succesfully (section \ref{sect:buildingCode})
812    then an executable called \texttt{mitgcmuv} will now exist in the
813    local directory.
814    
815  If compilation finished succesfuully (section \ref{sect:buildModel})  To run the model as a single process (\textit{ie.} not in parallel)
816  then an executable called {\em mitgcmuv} will now exist in the local  simply type:
 directory.  
   
 To run the model as a single process (ie. not in parallel) simply  
 type:  
817  \begin{verbatim}  \begin{verbatim}
818  % ./mitgcmuv  % ./mitgcmuv
819  \end{verbatim}  \end{verbatim}
# Line 543  do!). The above command will spew out ma Line 823  do!). The above command will spew out ma
823  your screen.  This output contains details such as parameter values as  your screen.  This output contains details such as parameter values as
824  well as diagnostics such as mean Kinetic energy, largest CFL number,  well as diagnostics such as mean Kinetic energy, largest CFL number,
825  etc. It is worth keeping this text output with the binary output so we  etc. It is worth keeping this text output with the binary output so we
826  normally re-direct the {\em stdout} stream as follows:  normally re-direct the \texttt{stdout} stream as follows:
827  \begin{verbatim}  \begin{verbatim}
828  % ./mitgcmuv > output.txt  % ./mitgcmuv > output.txt
829  \end{verbatim}  \end{verbatim}
830    In the event that the model encounters an error and stops, it is very
831  For the example experiments in {\em vericication}, an example of the  helpful to include the last few line of this \texttt{output.txt} file
832  output is kept in {\em results/output.txt} for comparison. You can compare  along with the (\texttt{stderr}) error message within any bug reports.
833  your {\em output.txt} with this one to check that the set-up works.  
834    For the example experiments in \texttt{verification}, an example of the
835    output is kept in \texttt{results/output.txt} for comparison. You can
836    compare your \texttt{output.txt} with the corresponding one for that
837    experiment to check that the set-up works.
838    
839    
840    
841  \subsection{Output files}  \subsection{Output files}
842    
843  The model produces various output files. At a minimum, the instantaneous  The model produces various output files and, when using \texttt{mnc},
844  ``state'' of the model is written out, which is made of the following files:  sometimes even directories.  Depending upon the I/O package(s)
845    selected at compile time (either \texttt{mdsio} or \texttt{mnc} or
846    both as determined by \texttt{code/packages.conf}) and the run-time
847    flags set (in \texttt{input/data.pkg}), the following output may
848    appear.
849    
850    
851    \subsubsection{MDSIO output files}
852    
853    The ``traditional'' output files are generated by the \texttt{mdsio}
854    package.  At a minimum, the instantaneous ``state'' of the model is
855    written out, which is made of the following files:
856    
857  \begin{itemize}  \begin{itemize}
858  \item \textit{U.00000nIter} - zonal component of velocity field (m/s and $>  \item \texttt{U.00000nIter} - zonal component of velocity field (m/s
859  0 $ eastward).    and positive eastward).
860    
861  \item \textit{V.00000nIter} - meridional component of velocity field (m/s  \item \texttt{V.00000nIter} - meridional component of velocity field
862  and $> 0$ northward).    (m/s and positive northward).
863    
864  \item \textit{W.00000nIter} - vertical component of velocity field (ocean:  \item \texttt{W.00000nIter} - vertical component of velocity field
865  m/s and $> 0$ upward, atmosphere: Pa/s and $> 0$ towards increasing pressure    (ocean: m/s and positive upward, atmosphere: Pa/s and positive
866  i.e. downward).    towards increasing pressure i.e. downward).
867    
868  \item \textit{T.00000nIter} - potential temperature (ocean: $^{0}$C,  \item \texttt{T.00000nIter} - potential temperature (ocean:
869  atmosphere: $^{0}$K).    $^{\circ}\mathrm{C}$, atmosphere: $^{\circ}\mathrm{K}$).
870    
871  \item \textit{S.00000nIter} - ocean: salinity (psu), atmosphere: water vapor  \item \texttt{S.00000nIter} - ocean: salinity (psu), atmosphere: water
872  (g/kg).    vapor (g/kg).
873    
874  \item \textit{Eta.00000nIter} - ocean: surface elevation (m), atmosphere:  \item \texttt{Eta.00000nIter} - ocean: surface elevation (m),
875  surface pressure anomaly (Pa).    atmosphere: surface pressure anomaly (Pa).
876  \end{itemize}  \end{itemize}
877    
878  The chain \textit{00000nIter} consists of ten figures that specify the  The chain \texttt{00000nIter} consists of ten figures that specify the
879  iteration number at which the output is written out. For example, \textit{%  iteration number at which the output is written out. For example,
880  U.0000000300} is the zonal velocity at iteration 300.  \texttt{U.0000000300} is the zonal velocity at iteration 300.
881    
882  In addition, a ``pickup'' or ``checkpoint'' file called:  In addition, a ``pickup'' or ``checkpoint'' file called:
883    
884  \begin{itemize}  \begin{itemize}
885  \item \textit{pickup.00000nIter}  \item \texttt{pickup.00000nIter}
886  \end{itemize}  \end{itemize}
887    
888  is written out. This file represents the state of the model in a condensed  is written out. This file represents the state of the model in a condensed
# Line 595  form and is used for restarting the inte Line 890  form and is used for restarting the inte
890  there is an additional ``pickup'' file:  there is an additional ``pickup'' file:
891    
892  \begin{itemize}  \begin{itemize}
893  \item \textit{pickup\_cd.00000nIter}  \item \texttt{pickup\_cd.00000nIter}
894  \end{itemize}  \end{itemize}
895    
896  containing the D-grid velocity data and that has to be written out as well  containing the D-grid velocity data and that has to be written out as well
897  in order to restart the integration. Rolling checkpoint files are the same  in order to restart the integration. Rolling checkpoint files are the same
898  as the pickup files but are named differently. Their name contain the chain  as the pickup files but are named differently. Their name contain the chain
899  \textit{ckptA} or \textit{ckptB} instead of \textit{00000nIter}. They can be  \texttt{ckptA} or \texttt{ckptB} instead of \texttt{00000nIter}. They can be
900  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
901  output to save disk space during long integrations.  output to save disk space during long integrations.
902    
903    \subsubsection{MNC output files}
904    
905    Unlike the \texttt{mdsio} output, the \texttt{mnc}--generated output
906    is usually (though not necessarily) placed within a subdirectory with
907    a name such as \texttt{mnc\_test\_\${DATE}\_\${SEQ}}.  
908    
909  \subsection{Looking at the output}  \subsection{Looking at the output}
910    
911  All the model data are written according to a ``meta/data'' file format.  The ``traditional'' or mdsio model data are written according to a
912  Each variable is associated with two files with suffix names \textit{.data}  ``meta/data'' file format.  Each variable is associated with two files
913  and \textit{.meta}. The \textit{.data} file contains the data written in  with suffix names \texttt{.data} and \texttt{.meta}. The
914  binary form (big\_endian by default). The \textit{.meta} file is a  \texttt{.data} file contains the data written in binary form
915  ``header'' file that contains information about the size and the structure  (big\_endian by default). The \texttt{.meta} file is a ``header'' file
916  of the \textit{.data} file. This way of organizing the output is  that contains information about the size and the structure of the
917  particularly useful when running multi-processors calculations. The base  \texttt{.data} file. This way of organizing the output is particularly
918  version of the model includes a few matlab utilities to read output files  useful when running multi-processors calculations. The base version of
919  written in this format. The matlab scripts are located in the directory  the model includes a few matlab utilities to read output files written
920  \textit{utils/matlab} under the root tree. The script \textit{rdmds.m} reads  in this format. The matlab scripts are located in the directory
921  the data. Look at the comments inside the script to see how to use it.  \texttt{utils/matlab} under the root tree. The script \texttt{rdmds.m}
922    reads the data. Look at the comments inside the script to see how to
923    use it.
924    
925  Some examples of reading and visualizing some output in {\em Matlab}:  Some examples of reading and visualizing some output in {\em Matlab}:
926  \begin{verbatim}  \begin{verbatim}
# Line 634  Some examples of reading and visualizing Line 937  Some examples of reading and visualizing
937  >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end  >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end
938  \end{verbatim}  \end{verbatim}
939    
940  \section{Doing it yourself: customizing the code}  Similar scripts for netCDF output (\texttt{rdmnc.m}) are available and
941    they are described in Section \ref{sec:pkg:mnc}.
 When you are ready to run the model in the configuration you want, the  
 easiest thing is to use and adapt the setup of the case studies experiment  
 (described previously) that is the closest to your configuration. Then, the  
 amount of setup will be minimized. In this section, we focus on the setup  
 relative to the ''numerical model'' part of the code (the setup relative to  
 the ''execution environment'' part is covered in the parallel implementation  
 section) and on the variables and parameters that you are likely to change.  
   
 \subsection{Configuration and setup}  
   
 The CPP keys relative to the ''numerical model'' part of the code are all  
 defined and set in the file \textit{CPP\_OPTIONS.h }in the directory \textit{%  
 model/inc }or in one of the \textit{code }directories of the case study  
 experiments under \textit{verification.} The model parameters are defined  
 and declared in the file \textit{model/inc/PARAMS.h }and their default  
 values are set in the routine \textit{model/src/set\_defaults.F. }The  
 default values can be modified in the namelist file \textit{data }which  
 needs to be located in the directory where you will run the model. The  
 parameters are initialized in the routine \textit{model/src/ini\_parms.F}.  
 Look at this routine to see in what part of the namelist the parameters are  
 located.  
   
 In what follows the parameters are grouped into categories related to the  
 computational domain, the equations solved in the model, and the simulation  
 controls.  
   
 \subsection{Computational domain, geometry and time-discretization}  
   
 \begin{itemize}  
 \item dimensions  
 \end{itemize}  
   
 The number of points in the x, y,\textit{\ }and r\textit{\ }directions are  
 represented by the variables \textbf{sNx}\textit{, }\textbf{sNy}\textit{, }%  
 and \textbf{Nr}\textit{\ }respectively which are declared and set in the  
 file \textit{model/inc/SIZE.h. }(Again, this assumes a mono-processor  
 calculation. For multiprocessor calculations see section on parallel  
 implementation.)  
   
 \begin{itemize}  
 \item grid  
 \end{itemize}  
   
 Three different grids are available: cartesian, spherical polar, and  
 curvilinear (including the cubed sphere). The grid is set through the  
 logical variables \textbf{usingCartesianGrid}\textit{, }\textbf{%  
 usingSphericalPolarGrid}\textit{, }and \textit{\ }\textbf{%  
 usingCurvilinearGrid}\textit{. }In the case of spherical and curvilinear  
 grids, the southern boundary is defined through the variable \textbf{phiMin}%  
 \textit{\ }which corresponds to the latitude of the southern most cell face  
 (in degrees). The resolution along the x and y directions is controlled by  
 the 1D arrays \textbf{delx}\textit{\ }and \textbf{dely}\textit{\ }(in meters  
 in the case of a cartesian grid, in degrees otherwise). The vertical grid  
 spacing is set through the 1D array \textbf{delz }for the ocean (in meters)  
 or \textbf{delp}\textit{\ }for the atmosphere (in Pa). The variable \textbf{%  
 Ro\_SeaLevel} represents the standard position of Sea-Level in ''R''  
 coordinate. This is typically set to 0m for the ocean (default value) and 10$%  
 ^{5}$Pa for the atmosphere. For the atmosphere, also set the logical  
 variable \textbf{groundAtK1} to '.\texttt{TRUE}.'. which put the first level  
 (k=1) at the lower boundary (ground).  
   
 For the cartesian grid case, the Coriolis parameter $f$ is set through the  
 variables \textbf{f0}\textit{\ }and \textbf{beta}\textit{\ }which correspond  
 to the reference Coriolis parameter (in s$^{-1}$) and $\frac{\partial f}{%  
 \partial y}$(in m$^{-1}$s$^{-1}$) respectively. If \textbf{beta }\textit{\ }%  
 is set to a nonzero value, \textbf{f0}\textit{\ }is the value of $f$ at the  
 southern edge of the domain.  
   
 \begin{itemize}  
 \item topography - full and partial cells  
 \end{itemize}  
   
 The domain bathymetry is read from a file that contains a 2D (x,y) map of  
 depths (in m) for the ocean or pressures (in Pa) for the atmosphere. The  
 file name is represented by the variable \textbf{bathyFile}\textit{. }The  
 file is assumed to contain binary numbers giving the depth (pressure) of the  
 model at each grid cell, ordered with the x coordinate varying fastest. The  
 points are ordered from low coordinate to high coordinate for both axes. The  
 model code applies without modification to enclosed, periodic, and double  
 periodic domains. Periodicity is assumed by default and is suppressed by  
 setting the depths to 0m for the cells at the limits of the computational  
 domain (note: not sure this is the case for the atmosphere). The precision  
 with which to read the binary data is controlled by the integer variable  
 \textbf{readBinaryPrec }which can take the value \texttt{32} (single  
 precision) or \texttt{64} (double precision). See the matlab program \textit{%  
 gendata.m }in the \textit{input }directories under \textit{verification }to  
 see how the bathymetry files are generated for the case study experiments.  
   
 To use the partial cell capability, the variable \textbf{hFacMin}\textit{\ }%  
 needs to be set to a value between 0 and 1 (it is set to 1 by default)  
 corresponding to the minimum fractional size of the cell. For example if the  
 bottom cell is 500m thick and \textbf{hFacMin}\textit{\ }is set to 0.1, the  
 actual thickness of the cell (i.e. used in the code) can cover a range of  
 discrete values 50m apart from 50m to 500m depending on the value of the  
 bottom depth (in \textbf{bathyFile}) at this point.  
   
 Note that the bottom depths (or pressures) need not coincide with the models  
 levels as deduced from \textbf{delz}\textit{\ }or\textit{\ }\textbf{delp}%  
 \textit{. }The model will interpolate the numbers in \textbf{bathyFile}%  
 \textit{\ }so that they match the levels obtained from \textbf{delz}\textit{%  
 \ }or\textit{\ }\textbf{delp}\textit{\ }and \textbf{hFacMin}\textit{. }  
   
 (Note: the atmospheric case is a bit more complicated than what is written  
 here I think. To come soon...)  
   
 \begin{itemize}  
 \item time-discretization  
 \end{itemize}  
   
 The time steps are set through the real variables \textbf{deltaTMom }and  
 \textbf{deltaTtracer }(in s) which represent the time step for the momentum  
 and tracer equations, respectively. For synchronous integrations, simply set  
 the two variables to the same value (or you can prescribe one time step only  
 through the variable \textbf{deltaT}). The Adams-Bashforth stabilizing  
 parameter is set through the variable \textbf{abEps }(dimensionless). The  
 stagger baroclinic time stepping can be activated by setting the logical  
 variable \textbf{staggerTimeStep }to '.\texttt{TRUE}.'.  
   
 \subsection{Equation of state}  
   
 First, because the model equations are written in terms of perturbations, a  
 reference thermodynamic state needs to be specified. This is done through  
 the 1D arrays \textbf{tRef}\textit{\ }and \textbf{sRef}. \textbf{tRef }%  
 specifies the reference potential temperature profile (in $^{o}$C for  
 the ocean and $^{o}$K for the atmosphere) starting from the level  
 k=1. Similarly, \textbf{sRef}\textit{\ }specifies the reference salinity  
 profile (in ppt) for the ocean or the reference specific humidity profile  
 (in g/kg) for the atmosphere.  
   
 The form of the equation of state is controlled by the character variables  
 \textbf{buoyancyRelation}\textit{\ }and \textbf{eosType}\textit{. }\textbf{%  
 buoyancyRelation}\textit{\ }is set to '\texttt{OCEANIC}' by default and  
 needs to be set to '\texttt{ATMOSPHERIC}' for atmosphere simulations. In  
 this case, \textbf{eosType}\textit{\ }must be set to '\texttt{IDEALGAS}'.  
 For the ocean, two forms of the equation of state are available: linear (set  
 \textbf{eosType}\textit{\ }to '\texttt{LINEAR}') and a polynomial  
 approximation to the full nonlinear equation ( set \textbf{eosType}\textit{\  
 }to '\texttt{POLYNOMIAL}'). In the linear case, you need to specify the  
 thermal and haline expansion coefficients represented by the variables  
 \textbf{tAlpha}\textit{\ }(in K$^{-1}$) and \textbf{sBeta}\textit{\ }(in ppt$%  
 ^{-1}$). For the nonlinear case, you need to generate a file of polynomial  
 coefficients called \textit{POLY3.COEFFS. }To do this, use the program  
 \textit{utils/knudsen2/knudsen2.f }under the model tree (a Makefile is  
 available in the same directory and you will need to edit the number and the  
 values of the vertical levels in \textit{knudsen2.f }so that they match  
 those of your configuration). \textit{\ }  
   
 \subsection{Momentum equations}  
   
 In this section, we only focus for now on the parameters that you are likely  
 to change, i.e. the ones relative to forcing and dissipation for example.  
 The details relevant to the vector-invariant form of the equations and the  
 various advection schemes are not covered for the moment. We assume that you  
 use the standard form of the momentum equations (i.e. the flux-form) with  
 the default advection scheme. Also, there are a few logical variables that  
 allow you to turn on/off various terms in the momentum equation. These  
 variables are called \textbf{momViscosity, momAdvection, momForcing,  
 useCoriolis, momPressureForcing, momStepping}\textit{, }and \textit{\ }%  
 \textbf{metricTerms }and are assumed to be set to '.\texttt{TRUE}.' here.  
 Look at the file \textit{model/inc/PARAMS.h }for a precise definition of  
 these variables.  
   
 \begin{itemize}  
 \item initialization  
 \end{itemize}  
   
 The velocity components are initialized to 0 unless the simulation is  
 starting from a pickup file (see section on simulation control parameters).  
   
 \begin{itemize}  
 \item forcing  
 \end{itemize}  
   
 This section only applies to the ocean. You need to generate wind-stress  
 data into two files \textbf{zonalWindFile}\textit{\ }and \textbf{%  
 meridWindFile }corresponding to the zonal and meridional components of the  
 wind stress, respectively (if you want the stress to be along the direction  
 of only one of the model horizontal axes, you only need to generate one  
 file). The format of the files is similar to the bathymetry file. The zonal  
 (meridional) stress data are assumed to be in Pa and located at U-points  
 (V-points). As for the bathymetry, the precision with which to read the  
 binary data is controlled by the variable \textbf{readBinaryPrec}.\textbf{\ }  
 See the matlab program \textit{gendata.m }in the \textit{input }directories  
 under \textit{verification }to see how simple analytical wind forcing data  
 are generated for the case study experiments.  
   
 There is also the possibility of prescribing time-dependent periodic  
 forcing. To do this, concatenate the successive time records into a single  
 file (for each stress component) ordered in a (x, y, t) fashion and set the  
 following variables: \textbf{periodicExternalForcing }to '.\texttt{TRUE}.',  
 \textbf{externForcingPeriod }to the period (in s) of which the forcing  
 varies (typically 1 month), and \textbf{externForcingCycle }to the repeat  
 time (in s) of the forcing (typically 1 year -- note: \textbf{%  
 externForcingCycle }must be a multiple of \textbf{externForcingPeriod}).  
 With these variables set up, the model will interpolate the forcing linearly  
 at each iteration.  
   
 \begin{itemize}  
 \item dissipation  
 \end{itemize}  
   
 The lateral eddy viscosity coefficient is specified through the variable  
 \textbf{viscAh}\textit{\ }(in m$^{2}$s$^{-1}$). The vertical eddy viscosity  
 coefficient is specified through the variable \textbf{viscAz }(in m$^{2}$s$%  
 ^{-1}$) for the ocean and \textbf{viscAp}\textit{\ }(in Pa$^{2}$s$^{-1}$)  
 for the atmosphere. The vertical diffusive fluxes can be computed implicitly  
 by setting the logical variable \textbf{implicitViscosity }to '.\texttt{TRUE}%  
 .'. In addition, biharmonic mixing can be added as well through the variable  
 \textbf{viscA4}\textit{\ }(in m$^{4}$s$^{-1}$). On a spherical polar grid,  
 you might also need to set the variable \textbf{cosPower} which is set to 0  
 by default and which represents the power of cosine of latitude to multiply  
 viscosity. Slip or no-slip conditions at lateral and bottom boundaries are  
 specified through the logical variables \textbf{no\_slip\_sides}\textit{\ }%  
 and \textbf{no\_slip\_bottom}. If set to '\texttt{.FALSE.}', free-slip  
 boundary conditions are applied. If no-slip boundary conditions are applied  
 at the bottom, a bottom drag can be applied as well. Two forms are  
 available: linear (set the variable \textbf{bottomDragLinear}\textit{\ }in s$%  
 ^{-1}$) and quadratic (set the variable \textbf{bottomDragQuadratic}\textit{%  
 \ }in m$^{-1}$).  
   
 The Fourier and Shapiro filters are described elsewhere.  
   
 \begin{itemize}  
 \item C-D scheme  
 \end{itemize}  
   
 If you run at a sufficiently coarse resolution, you will need the C-D scheme  
 for the computation of the Coriolis terms. The variable\textbf{\ tauCD},  
 which represents the C-D scheme coupling timescale (in s) needs to be set.  
   
 \begin{itemize}  
 \item calculation of pressure/geopotential  
 \end{itemize}  
   
 First, to run a non-hydrostatic ocean simulation, set the logical variable  
 \textbf{nonHydrostatic} to '.\texttt{TRUE}.'. The pressure field is then  
 inverted through a 3D elliptic equation. (Note: this capability is not  
 available for the atmosphere yet.) By default, a hydrostatic simulation is  
 assumed and a 2D elliptic equation is used to invert the pressure field. The  
 parameters controlling the behaviour of the elliptic solvers are the  
 variables \textbf{cg2dMaxIters}\textit{\ }and \textbf{cg2dTargetResidual }%  
 for the 2D case and \textbf{cg3dMaxIters}\textit{\ }and \textbf{%  
 cg3dTargetResidual }for the 3D case. You probably won't need to alter the  
 default values (are we sure of this?).  
   
 For the calculation of the surface pressure (for the ocean) or surface  
 geopotential (for the atmosphere) you need to set the logical variables  
 \textbf{rigidLid} and \textbf{implicitFreeSurface}\textit{\ }(set one to '.%  
 \texttt{TRUE}.' and the other to '.\texttt{FALSE}.' depending on how you  
 want to deal with the ocean upper or atmosphere lower boundary).  
   
 \subsection{Tracer equations}  
   
 This section covers the tracer equations i.e. the potential temperature  
 equation and the salinity (for the ocean) or specific humidity (for the  
 atmosphere) equation. As for the momentum equations, we only describe for  
 now the parameters that you are likely to change. The logical variables  
 \textbf{tempDiffusion}\textit{, }\textbf{tempAdvection}\textit{, }\textbf{%  
 tempForcing}\textit{,} and \textbf{tempStepping} allow you to turn on/off  
 terms in the temperature equation (same thing for salinity or specific  
 humidity with variables \textbf{saltDiffusion}\textit{, }\textbf{%  
 saltAdvection}\textit{\ }etc). These variables are all assumed here to be  
 set to '.\texttt{TRUE}.'. Look at file \textit{model/inc/PARAMS.h }for a  
 precise definition.  
   
 \begin{itemize}  
 \item initialization  
 \end{itemize}  
   
 The initial tracer data can be contained in the binary files \textbf{%  
 hydrogThetaFile }and \textbf{hydrogSaltFile}. These files should contain 3D  
 data ordered in an (x, y, r) fashion with k=1 as the first vertical level.  
 If no file names are provided, the tracers are then initialized with the  
 values of \textbf{tRef }and \textbf{sRef }mentioned above (in the equation  
 of state section). In this case, the initial tracer data are uniform in x  
 and y for each depth level.  
   
 \begin{itemize}  
 \item forcing  
 \end{itemize}  
   
 This part is more relevant for the ocean, the procedure for the atmosphere  
 not being completely stabilized at the moment.  
   
 A combination of fluxes data and relaxation terms can be used for driving  
 the tracer equations. \ For potential temperature, heat flux data (in W/m$%  
 ^{2}$) can be stored in the 2D binary file \textbf{surfQfile}\textit{. }%  
 Alternatively or in addition, the forcing can be specified through a  
 relaxation term. The SST data to which the model surface temperatures are  
 restored to are supposed to be stored in the 2D binary file \textbf{%  
 thetaClimFile}\textit{. }The corresponding relaxation time scale coefficient  
 is set through the variable \textbf{tauThetaClimRelax}\textit{\ }(in s). The  
 same procedure applies for salinity with the variable names \textbf{EmPmRfile%  
 }\textit{, }\textbf{saltClimFile}\textit{, }and \textbf{tauSaltClimRelax}%  
 \textit{\ }for freshwater flux (in m/s) and surface salinity (in ppt) data  
 files and relaxation time scale coefficient (in s), respectively. Also for  
 salinity, if the CPP key \textbf{USE\_NATURAL\_BCS} is turned on, natural  
 boundary conditions are applied i.e. when computing the surface salinity  
 tendency, the freshwater flux is multiplied by the model surface salinity  
 instead of a constant salinity value.  
   
 As for the other input files, the precision with which to read the data is  
 controlled by the variable \textbf{readBinaryPrec}. Time-dependent, periodic  
 forcing can be applied as well following the same procedure used for the  
 wind forcing data (see above).  
942    
943    The MNC output files are all in the ``self-describing'' netCDF
944    format and can thus be browsed and/or plotted using tools such as:
945  \begin{itemize}  \begin{itemize}
946  \item dissipation  \item \texttt{ncdump} is a utility which is typically included
947  \end{itemize}    with every netCDF install:
948      \begin{rawhtml} <A href="http://www.unidata.ucar.edu/packages/netcdf/"> \end{rawhtml}
949  Lateral eddy diffusivities for temperature and salinity/specific humidity  \begin{verbatim}
950  are specified through the variables \textbf{diffKhT }and \textbf{diffKhS }%  http://www.unidata.ucar.edu/packages/netcdf/
951  (in m$^{2}$/s). Vertical eddy diffusivities are specified through the  \end{verbatim}
952  variables \textbf{diffKzT }and \textbf{diffKzS }(in m$^{2}$/s) for the ocean    \begin{rawhtml} </A> \end{rawhtml} and it converts the netCDF
953  and \textbf{diffKpT }and \textbf{diffKpS }(in Pa$^{2}$/s) for the    binaries into formatted ASCII text files.
 atmosphere. The vertical diffusive fluxes can be computed implicitly by  
 setting the logical variable \textbf{implicitDiffusion }to '.\texttt{TRUE}%  
 .'. In addition, biharmonic diffusivities can be specified as well through  
 the coefficients \textbf{diffK4T }and \textbf{diffK4S }(in m$^{4}$/s). Note  
 that the cosine power scaling (specified through \textbf{cosPower }- see the  
 momentum equations section) is applied to the tracer diffusivities  
 (Laplacian and biharmonic) as well. The Gent and McWilliams parameterization  
 for oceanic tracers is described in the package section. Finally, note that  
 tracers can be also subject to Fourier and Shapiro filtering (see the  
 corresponding section on these filters).  
   
 \begin{itemize}  
 \item ocean convection  
 \end{itemize}  
   
 Two options are available to parameterize ocean convection: one is to use  
 the convective adjustment scheme. In this case, you need to set the variable  
 \textbf{cadjFreq}, which represents the frequency (in s) with which the  
 adjustment algorithm is called, to a non-zero value (if set to a negative  
 value by the user, the model will set it to the tracer time step). The other  
 option is to parameterize convection with implicit vertical diffusion. To do  
 this, set the logical variable \textbf{implicitDiffusion }to '.\texttt{TRUE}%  
 .' and the real variable \textbf{ivdc\_kappa }to a value (in m$^{2}$/s) you  
 wish the tracer vertical diffusivities to have when mixing tracers  
 vertically due to static instabilities. Note that \textbf{cadjFreq }and  
 \textbf{ivdc\_kappa }can not both have non-zero value.  
   
 \subsection{Simulation controls}  
   
 The model ''clock'' is defined by the variable \textbf{deltaTClock }(in s)  
 which determines the IO frequencies and is used in tagging output.  
 Typically, you will set it to the tracer time step for accelerated runs  
 (otherwise it is simply set to the default time step \textbf{deltaT}).  
 Frequency of checkpointing and dumping of the model state are referenced to  
 this clock (see below).  
   
 \begin{itemize}  
 \item run duration  
 \end{itemize}  
   
 The beginning of a simulation is set by specifying a start time (in s)  
 through the real variable \textbf{startTime }or by specifying an initial  
 iteration number through the integer variable \textbf{nIter0}. If these  
 variables are set to nonzero values, the model will look for a ''pickup''  
 file \textit{pickup.0000nIter0 }to restart the integration\textit{. }The end  
 of a simulation is set through the real variable \textbf{endTime }(in s).  
 Alternatively, you can specify instead the number of time steps to execute  
 through the integer variable \textbf{nTimeSteps}.  
954    
955  \begin{itemize}  \item \texttt{ncview} utility is a very convenient and quick way
956  \item frequency of output    to plot netCDF data and it runs on most OSes:
957      \begin{rawhtml} <A href="http://meteora.ucsd.edu/~pierce/ncview_home_page.html"> \end{rawhtml}
958    \begin{verbatim}
959    http://meteora.ucsd.edu/~pierce/ncview_home_page.html
960    \end{verbatim}
961      \begin{rawhtml} </A> \end{rawhtml}
962      
963    \item MatLAB(c) and other common post-processing environments provide
964      various netCDF interfaces including:
965      \begin{rawhtml} <A href="http://mexcdf.sourceforge.net/"> \end{rawhtml}
966    \begin{verbatim}
967    http://mexcdf.sourceforge.net/
968    \end{verbatim}
969      \begin{rawhtml} </A> \end{rawhtml}
970      \begin{rawhtml} <A href="http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html"> \end{rawhtml}
971    \begin{verbatim}
972    http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html
973    \end{verbatim}
974      \begin{rawhtml} </A> \end{rawhtml}
975  \end{itemize}  \end{itemize}
976    
 Real variables defining frequencies (in s) with which output files are  
 written on disk need to be set up. \textbf{dumpFreq }controls the frequency  
 with which the instantaneous state of the model is saved. \textbf{chkPtFreq }%  
 and \textbf{pchkPtFreq }control the output frequency of rolling and  
 permanent checkpoint files, respectively. See section 1.5.1 Output files for the  
 definition of model state and checkpoint files. In addition, time-averaged  
 fields can be written out by setting the variable \textbf{taveFreq} (in s).  
 The precision with which to write the binary data is controlled by the  
 integer variable w\textbf{riteBinaryPrec }(set it to \texttt{32} or \texttt{%  
 64}).  

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