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1 molod 1.37 % $Header: /u/gcmpack/manual/part3/getting_started.tex,v 1.36 2006/06/27 19:08:22 molod Exp $
2 adcroft 1.2 % $Name: $
3 adcroft 1.1
4 adcroft 1.4 %\section{Getting started}
5 adcroft 1.1
6 adcroft 1.4 In this section, we describe how to use the model. In the first
7     section, we provide enough information to help you get started with
8     the model. We believe the best way to familiarize yourself with the
9     model is to run the case study examples provided with the base
10     version. Information on how to obtain, compile, and run the code is
11     found there as well as a brief description of the model structure
12     directory and the case study examples. The latter and the code
13     structure are described more fully in chapters
14     \ref{chap:discretization} and \ref{chap:sarch}, respectively. Here, in
15     this section, we provide information on how to customize the code when
16     you are ready to try implementing the configuration you have in mind.
17    
18     \section{Where to find information}
19     \label{sect:whereToFindInfo}
20 edhill 1.30 \begin{rawhtml}
21     <!-- CMIREDIR:whereToFindInfo: -->
22     \end{rawhtml}
23 adcroft 1.4
24 molod 1.37 There is a web-archived support mailing list for the model that
25 edhill 1.15 you can email at \texttt{MITgcm-support@mitgcm.org} or browse at:
26     \begin{rawhtml} <A href=http://mitgcm.org/mailman/listinfo/mitgcm-support/ target="idontexist"> \end{rawhtml}
27     \begin{verbatim}
28     http://mitgcm.org/mailman/listinfo/mitgcm-support/
29     http://mitgcm.org/pipermail/mitgcm-support/
30     \end{verbatim}
31     \begin{rawhtml} </A> \end{rawhtml}
32 adcroft 1.4
33     \section{Obtaining the code}
34     \label{sect:obtainingCode}
35 edhill 1.30 \begin{rawhtml}
36     <!-- CMIREDIR:obtainingCode: -->
37     \end{rawhtml}
38 adcroft 1.1
39 cnh 1.7 MITgcm can be downloaded from our system by following
40     the instructions below. As a courtesy we ask that you send e-mail to us at
41 edhill 1.14 \begin{rawhtml} <A href=mailto:MITgcm-support@mitgcm.org> \end{rawhtml}
42     MITgcm-support@mitgcm.org
43 cnh 1.7 \begin{rawhtml} </A> \end{rawhtml}
44     to enable us to keep track of who's using the model and in what application.
45     You can download the model two ways:
46    
47     \begin{enumerate}
48 cnh 1.9 \item Using CVS software. CVS is a freely available source code management
49 cnh 1.7 tool. To use CVS you need to have the software installed. Many systems
50     come with CVS pre-installed, otherwise good places to look for
51     the software for a particular platform are
52     \begin{rawhtml} <A href=http://www.cvshome.org/ target="idontexist"> \end{rawhtml}
53     cvshome.org
54     \begin{rawhtml} </A> \end{rawhtml}
55     and
56     \begin{rawhtml} <A href=http://www.wincvs.org/ target="idontexist"> \end{rawhtml}
57     wincvs.org
58     \begin{rawhtml} </A> \end{rawhtml}
59     .
60    
61     \item Using a tar file. This method is simple and does not
62     require any special software. However, this method does not
63     provide easy support for maintenance updates.
64    
65     \end{enumerate}
66    
67 cnh 1.27 \subsection{Method 1 - Checkout from CVS}
68 edhill 1.19 \label{sect:cvs_checkout}
69    
70 adcroft 1.1 If CVS is available on your system, we strongly encourage you to use it. CVS
71     provides an efficient and elegant way of organizing your code and keeping
72     track of your changes. If CVS is not available on your machine, you can also
73     download a tar file.
74    
75 edhill 1.15 Before you can use CVS, the following environment variable(s) should
76     be set within your shell. For a csh or tcsh shell, put the following
77     \begin{verbatim}
78     % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/gcmpack
79     \end{verbatim}
80 edhill 1.31 in your \texttt{.cshrc} or \texttt{.tcshrc} file. For bash or sh
81     shells, put:
82 adcroft 1.1 \begin{verbatim}
83 edhill 1.15 % export CVSROOT=':pserver:cvsanon@mitgcm.org:/u/gcmpack'
84 adcroft 1.6 \end{verbatim}
85 edhill 1.20 in your \texttt{.profile} or \texttt{.bashrc} file.
86 adcroft 1.6
87 edhill 1.15
88     To get MITgcm through CVS, first register with the MITgcm CVS server
89     using command:
90 adcroft 1.6 \begin{verbatim}
91 adcroft 1.1 % cvs login ( CVS password: cvsanon )
92     \end{verbatim}
93 edhill 1.15 You only need to do a ``cvs login'' once.
94 adcroft 1.1
95 edhill 1.15 To obtain the latest sources type:
96     \begin{verbatim}
97     % cvs co MITgcm
98     \end{verbatim}
99     or to get a specific release type:
100 adcroft 1.1 \begin{verbatim}
101 edhill 1.16 % cvs co -P -r checkpoint52i_post MITgcm
102 adcroft 1.1 \end{verbatim}
103 edhill 1.15 The MITgcm web site contains further directions concerning the source
104     code and CVS. It also contains a web interface to our CVS archive so
105     that one may easily view the state of files, revisions, and other
106     development milestones:
107 edhill 1.34 \begin{rawhtml} <A href="http://mitgcm.org/download" target="idontexist"> \end{rawhtml}
108 edhill 1.15 \begin{verbatim}
109 edhill 1.17 http://mitgcm.org/source_code.html
110 edhill 1.15 \end{verbatim}
111     \begin{rawhtml} </A> \end{rawhtml}
112 adcroft 1.1
113 edhill 1.19 As a convenience, the MITgcm CVS server contains aliases which are
114     named subsets of the codebase. These aliases can be especially
115     helpful when used over slow internet connections or on machines with
116     restricted storage space. Table \ref{tab:cvsModules} contains a list
117     of CVS aliases
118     \begin{table}[htb]
119     \centering
120     \begin{tabular}[htb]{|lp{3.25in}|}\hline
121     \textbf{Alias Name} & \textbf{Information (directories) Contained} \\\hline
122     \texttt{MITgcm\_code} & Only the source code -- none of the verification examples. \\
123     \texttt{MITgcm\_verif\_basic}
124     & Source code plus a small set of the verification examples
125     (\texttt{global\_ocean.90x40x15}, \texttt{aim.5l\_cs}, \texttt{hs94.128x64x5},
126     \texttt{front\_relax}, and \texttt{plume\_on\_slope}). \\
127     \texttt{MITgcm\_verif\_atmos} & Source code plus all of the atmospheric examples. \\
128     \texttt{MITgcm\_verif\_ocean} & Source code plus all of the oceanic examples. \\
129     \texttt{MITgcm\_verif\_all} & Source code plus all of the
130     verification examples. \\\hline
131     \end{tabular}
132     \caption{MITgcm CVS Modules}
133     \label{tab:cvsModules}
134     \end{table}
135 edhill 1.15
136 edhill 1.31 The checkout process creates a directory called \texttt{MITgcm}. If
137     the directory \texttt{MITgcm} exists this command updates your code
138 edhill 1.15 based on the repository. Each directory in the source tree contains a
139 edhill 1.31 directory \texttt{CVS}. This information is required by CVS to keep
140 edhill 1.15 track of your file versions with respect to the repository. Don't edit
141 edhill 1.31 the files in \texttt{CVS}! You can also use CVS to download code
142 edhill 1.15 updates. More extensive information on using CVS for maintaining
143     MITgcm code can be found
144 edhill 1.34 \begin{rawhtml} <A href="http://mitgcm.org/usingcvstoget.html" target="idontexist"> \end{rawhtml}
145 cnh 1.7 here
146     \begin{rawhtml} </A> \end{rawhtml}
147     .
148 edhill 1.19 It is important to note that the CVS aliases in Table
149     \ref{tab:cvsModules} cannot be used in conjunction with the CVS
150     \texttt{-d DIRNAME} option. However, the \texttt{MITgcm} directories
151     they create can be changed to a different name following the check-out:
152     \begin{verbatim}
153     % cvs co MITgcm_verif_basic
154     % mv MITgcm MITgcm_verif_basic
155     \end{verbatim}
156 cnh 1.7
157 edhill 1.19 \subsubsection{Upgrading from an earlier version}
158 adcroft 1.12
159     If you already have an earlier version of the code you can ``upgrade''
160     your copy instead of downloading the entire repository again. First,
161     ``cd'' (change directory) to the top of your working copy:
162     \begin{verbatim}
163     % cd MITgcm
164     \end{verbatim}
165 edhill 1.15 and then issue the cvs update command such as:
166 adcroft 1.12 \begin{verbatim}
167 edhill 1.16 % cvs -q update -r checkpoint52i_post -d -P
168 adcroft 1.12 \end{verbatim}
169 edhill 1.16 This will update the ``tag'' to ``checkpoint52i\_post'', add any new
170 adcroft 1.12 directories (-d) and remove any empty directories (-P). The -q option
171     means be quiet which will reduce the number of messages you'll see in
172     the terminal. If you have modified the code prior to upgrading, CVS
173     will try to merge your changes with the upgrades. If there is a
174     conflict between your modifications and the upgrade, it will report
175     that file with a ``C'' in front, e.g.:
176     \begin{verbatim}
177     C model/src/ini_parms.F
178     \end{verbatim}
179     If the list of conflicts scrolled off the screen, you can re-issue the
180     cvs update command and it will report the conflicts. Conflicts are
181 edhill 1.15 indicated in the code by the delimites ``$<<<<<<<$'', ``======='' and
182     ``$>>>>>>>$''. For example,
183 edhill 1.17 {\small
184 adcroft 1.12 \begin{verbatim}
185     <<<<<<< ini_parms.F
186     & bottomDragLinear,myOwnBottomDragCoefficient,
187     =======
188     & bottomDragLinear,bottomDragQuadratic,
189     >>>>>>> 1.18
190     \end{verbatim}
191 edhill 1.17 }
192 adcroft 1.12 means that you added ``myOwnBottomDragCoefficient'' to a namelist at
193     the same time and place that we added ``bottomDragQuadratic''. You
194     need to resolve this conflict and in this case the line should be
195     changed to:
196 edhill 1.17 {\small
197 adcroft 1.12 \begin{verbatim}
198     & bottomDragLinear,bottomDragQuadratic,myOwnBottomDragCoefficient,
199     \end{verbatim}
200 edhill 1.17 }
201 edhill 1.15 and the lines with the delimiters ($<<<<<<$,======,$>>>>>>$) be deleted.
202 adcroft 1.12 Unless you are making modifications which exactly parallel
203     developments we make, these types of conflicts should be rare.
204    
205     \paragraph*{Upgrading to the current pre-release version}
206    
207     We don't make a ``release'' for every little patch and bug fix in
208     order to keep the frequency of upgrades to a minimum. However, if you
209     have run into a problem for which ``we have already fixed in the
210     latest code'' and we haven't made a ``tag'' or ``release'' since that
211     patch then you'll need to get the latest code:
212     \begin{verbatim}
213     % cvs -q update -A -d -P
214     \end{verbatim}
215     Unlike, the ``check-out'' and ``update'' procedures above, there is no
216     ``tag'' or release name. The -A tells CVS to upgrade to the
217     very latest version. As a rule, we don't recommend this since you
218     might upgrade while we are in the processes of checking in the code so
219     that you may only have part of a patch. Using this method of updating
220     also means we can't tell what version of the code you are working
221     with. So please be sure you understand what you're doing.
222    
223 molod 1.37 \subsection{Method 2 - Tar file download}
224     \label{sect:conventionalDownload}
225    
226     If you do not have CVS on your system, you can download the model as a
227     tar file from the web site at:
228     \begin{rawhtml} <A href=http://mitgcm.org/download target="idontexist"> \end{rawhtml}
229     \begin{verbatim}
230     http://mitgcm.org/download/
231     \end{verbatim}
232     \begin{rawhtml} </A> \end{rawhtml}
233     The tar file still contains CVS information which we urge you not to
234     delete; even if you do not use CVS yourself the information can help
235     us if you should need to send us your copy of the code. If a recent
236     tar file does not exist, then please contact the developers through
237     the
238     \begin{rawhtml} <A href="mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
239     MITgcm-support@mitgcm.org
240     \begin{rawhtml} </A> \end{rawhtml}
241     mailing list.
242    
243 adcroft 1.4 \section{Model and directory structure}
244 edhill 1.30 \begin{rawhtml}
245     <!-- CMIREDIR:directory_structure: -->
246     \end{rawhtml}
247 adcroft 1.1
248 adcroft 1.12 The ``numerical'' model is contained within a execution environment
249     support wrapper. This wrapper is designed to provide a general
250     framework for grid-point models. MITgcmUV is a specific numerical
251     model that uses the framework. Under this structure the model is split
252     into execution environment support code and conventional numerical
253     model code. The execution environment support code is held under the
254 edhill 1.31 \texttt{eesupp} directory. The grid point model code is held under the
255     \texttt{model} directory. Code execution actually starts in the
256     \texttt{eesupp} routines and not in the \texttt{model} routines. For
257     this reason the top-level \texttt{MAIN.F} is in the
258     \texttt{eesupp/src} directory. In general, end-users should not need
259 edhill 1.17 to worry about this level. The top-level routine for the numerical
260 edhill 1.31 part of the code is in \texttt{model/src/THE\_MODEL\_MAIN.F}. Here is
261 edhill 1.17 a brief description of the directory structure of the model under the
262     root tree (a detailed description is given in section 3: Code
263     structure).
264 adcroft 1.1
265     \begin{itemize}
266    
267 edhill 1.31 \item \texttt{doc}: contains brief documentation notes.
268    
269     \item \texttt{eesupp}: contains the execution environment source code.
270     Also subdivided into two subdirectories \texttt{inc} and
271     \texttt{src}.
272 edhill 1.17
273 edhill 1.31 \item \texttt{model}: this directory contains the main source code.
274     Also subdivided into two subdirectories \texttt{inc} and
275     \texttt{src}.
276 edhill 1.17
277 edhill 1.31 \item \texttt{pkg}: contains the source code for the packages. Each
278     package corresponds to a subdirectory. For example, \texttt{gmredi}
279 edhill 1.17 contains the code related to the Gent-McWilliams/Redi scheme,
280 edhill 1.31 \texttt{aim} the code relative to the atmospheric intermediate
281 molod 1.37 physics. The packages are described in detail in chapter \ref{chap.packagesI}.
282 edhill 1.17
283 edhill 1.31 \item \texttt{tools}: this directory contains various useful tools.
284     For example, \texttt{genmake2} is a script written in csh (C-shell)
285 edhill 1.17 that should be used to generate your makefile. The directory
286 edhill 1.31 \texttt{adjoint} contains the makefile specific to the Tangent
287 edhill 1.17 linear and Adjoint Compiler (TAMC) that generates the adjoint code.
288 molod 1.37 The latter is described in detail in part \ref{chap.ecco}.
289     This directory also contains the subdirectory build\_options, which
290     contains the `optfiles' with the compiler options for the different
291     compilers and machines that can run MITgcm.
292 edhill 1.17
293 edhill 1.31 \item \texttt{utils}: this directory contains various utilities. The
294     subdirectory \texttt{knudsen2} contains code and a makefile that
295 edhill 1.17 compute coefficients of the polynomial approximation to the knudsen
296     formula for an ocean nonlinear equation of state. The
297 edhill 1.31 \texttt{matlab} subdirectory contains matlab scripts for reading
298     model output directly into matlab. \texttt{scripts} contains C-shell
299 edhill 1.17 post-processing scripts for joining processor-based and tiled-based
300 molod 1.37 model output. The subdirectory exch2 contains the code needed for
301     the exch2 package to work with different combinations of domain
302     decompositions.
303 edhill 1.17
304 edhill 1.31 \item \texttt{verification}: this directory contains the model
305 edhill 1.17 examples. See section \ref{sect:modelExamples}.
306 adcroft 1.1
307 molod 1.37 \item \texttt{jobs}: contains sample job scripts for running MITgcm.
308    
309     \item \texttt{lsopt}: Line search code used for optimization.
310    
311     \item \texttt{optim}: Interface between MITgcm and line search code.
312    
313 adcroft 1.1 \end{itemize}
314    
315 cnh 1.26 \section[Building MITgcm]{Building the code}
316 adcroft 1.4 \label{sect:buildingCode}
317 edhill 1.30 \begin{rawhtml}
318     <!-- CMIREDIR:buildingCode: -->
319     \end{rawhtml}
320 adcroft 1.4
321 edhill 1.31 To compile the code, we use the \texttt{make} program. This uses a
322     file (\texttt{Makefile}) that allows us to pre-process source files,
323     specify compiler and optimization options and also figures out any
324     file dependencies. We supply a script (\texttt{genmake2}), described
325     in section \ref{sect:genmake}, that automatically creates the
326     \texttt{Makefile} for you. You then need to build the dependencies and
327 edhill 1.16 compile the code.
328 adcroft 1.4
329 edhill 1.31 As an example, assume that you want to build and run experiment
330     \texttt{verification/exp2}. The are multiple ways and places to
331 edhill 1.16 actually do this but here let's build the code in
332 edhill 1.31 \texttt{verification/exp2/build}:
333 adcroft 1.4 \begin{verbatim}
334 edhill 1.31 % cd verification/exp2/build
335 adcroft 1.4 \end{verbatim}
336 edhill 1.31 First, build the \texttt{Makefile}:
337 adcroft 1.4 \begin{verbatim}
338 edhill 1.16 % ../../../tools/genmake2 -mods=../code
339 adcroft 1.4 \end{verbatim}
340 edhill 1.31 The command line option tells \texttt{genmake} to override model source
341     code with any files in the directory \texttt{../code/}.
342 adcroft 1.4
343 edhill 1.31 On many systems, the \texttt{genmake2} program will be able to
344 edhill 1.16 automatically recognize the hardware, find compilers and other tools
345 edhill 1.31 within the user's path (``\texttt{echo \$PATH}''), and then choose an
346 edhill 1.29 appropriate set of options from the files (``optfiles'') contained in
347 edhill 1.31 the \texttt{tools/build\_options} directory. Under some
348     circumstances, a user may have to create a new ``optfile'' in order to
349     specify the exact combination of compiler, compiler flags, libraries,
350     and other options necessary to build a particular configuration of
351     MITgcm. In such cases, it is generally helpful to read the existing
352     ``optfiles'' and mimic their syntax.
353 edhill 1.16
354     Through the MITgcm-support list, the MITgcm developers are willing to
355     provide help writing or modifing ``optfiles''. And we encourage users
356     to post new ``optfiles'' (particularly ones for new machines or
357 edhill 1.17 architectures) to the
358 edhill 1.34 \begin{rawhtml} <A href="mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
359 edhill 1.17 MITgcm-support@mitgcm.org
360     \begin{rawhtml} </A> \end{rawhtml}
361     list.
362 edhill 1.16
363 edhill 1.31 To specify an optfile to \texttt{genmake2}, the syntax is:
364 adcroft 1.4 \begin{verbatim}
365 edhill 1.16 % ../../../tools/genmake2 -mods=../code -of /path/to/optfile
366 adcroft 1.4 \end{verbatim}
367    
368 edhill 1.31 Once a \texttt{Makefile} has been generated, we create the
369     dependencies with the command:
370 adcroft 1.4 \begin{verbatim}
371     % make depend
372     \end{verbatim}
373 edhill 1.31 This modifies the \texttt{Makefile} by attaching a (usually, long)
374     list of files upon which other files depend. The purpose of this is to
375     reduce re-compilation if and when you start to modify the code. The
376     {\tt make depend} command also creates links from the model source to
377     this directory. It is important to note that the {\tt make depend}
378     stage will occasionally produce warnings or errors since the
379     dependency parsing tool is unable to find all of the necessary header
380     files (\textit{eg.} \texttt{netcdf.inc}). In these circumstances, it
381     is usually OK to ignore the warnings/errors and proceed to the next
382     step.
383 adcroft 1.1
384 edhill 1.31 Next one can compile the code using:
385 adcroft 1.4 \begin{verbatim}
386     % make
387     \end{verbatim}
388 edhill 1.31 The {\tt make} command creates an executable called \texttt{mitgcmuv}.
389 edhill 1.16 Additional make ``targets'' are defined within the makefile to aid in
390 edhill 1.31 the production of adjoint and other versions of MITgcm. On SMP
391     (shared multi-processor) systems, the build process can often be sped
392     up appreciably using the command:
393     \begin{verbatim}
394     % make -j 2
395     \end{verbatim}
396     where the ``2'' can be replaced with a number that corresponds to the
397     number of CPUs available.
398 adcroft 1.4
399     Now you are ready to run the model. General instructions for doing so are
400 edhill 1.31 given in section \ref{sect:runModel}. Here, we can run the model by
401     first creating links to all the input files:
402     \begin{verbatim}
403     ln -s ../input/* .
404     \end{verbatim}
405     and then calling the executable with:
406 adcroft 1.4 \begin{verbatim}
407     ./mitgcmuv > output.txt
408     \end{verbatim}
409 edhill 1.31 where we are re-directing the stream of text output to the file
410     \texttt{output.txt}.
411 adcroft 1.4
412 molod 1.35 \subsection{Building/compiling the code elsewhere}
413    
414     In the example above (section \ref{sect:buildingCode}) we built the
415     executable in the {\em input} directory of the experiment for
416     convenience. You can also configure and compile the code in other
417     locations, for example on a scratch disk with out having to copy the
418     entire source tree. The only requirement to do so is you have {\tt
419     genmake2} in your path or you know the absolute path to {\tt
420     genmake2}.
421    
422     The following sections outline some possible methods of organizing
423     your source and data.
424    
425     \subsubsection{Building from the {\em ../code directory}}
426    
427     This is just as simple as building in the {\em input/} directory:
428     \begin{verbatim}
429     % cd verification/exp2/code
430     % ../../../tools/genmake2
431     % make depend
432     % make
433     \end{verbatim}
434     However, to run the model the executable ({\em mitgcmuv}) and input
435     files must be in the same place. If you only have one calculation to make:
436     \begin{verbatim}
437     % cd ../input
438     % cp ../code/mitgcmuv ./
439     % ./mitgcmuv > output.txt
440     \end{verbatim}
441     or if you will be making multiple runs with the same executable:
442     \begin{verbatim}
443     % cd ../
444     % cp -r input run1
445     % cp code/mitgcmuv run1
446     % cd run1
447     % ./mitgcmuv > output.txt
448     \end{verbatim}
449    
450     \subsubsection{Building from a new directory}
451    
452     Since the {\em input} directory contains input files it is often more
453     useful to keep {\em input} pristine and build in a new directory
454     within {\em verification/exp2/}:
455     \begin{verbatim}
456     % cd verification/exp2
457     % mkdir build
458     % cd build
459     % ../../../tools/genmake2 -mods=../code
460     % make depend
461     % make
462     \end{verbatim}
463     This builds the code exactly as before but this time you need to copy
464     either the executable or the input files or both in order to run the
465     model. For example,
466     \begin{verbatim}
467     % cp ../input/* ./
468     % ./mitgcmuv > output.txt
469     \end{verbatim}
470     or if you tend to make multiple runs with the same executable then
471     running in a new directory each time might be more appropriate:
472     \begin{verbatim}
473     % cd ../
474     % mkdir run1
475     % cp build/mitgcmuv run1/
476     % cp input/* run1/
477     % cd run1
478     % ./mitgcmuv > output.txt
479     \end{verbatim}
480    
481     \subsubsection{Building on a scratch disk}
482    
483     Model object files and output data can use up large amounts of disk
484     space so it is often the case that you will be operating on a large
485     scratch disk. Assuming the model source is in {\em ~/MITgcm} then the
486     following commands will build the model in {\em /scratch/exp2-run1}:
487     \begin{verbatim}
488     % cd /scratch/exp2-run1
489     % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
490     -mods=~/MITgcm/verification/exp2/code
491     % make depend
492     % make
493     \end{verbatim}
494     To run the model here, you'll need the input files:
495     \begin{verbatim}
496     % cp ~/MITgcm/verification/exp2/input/* ./
497     % ./mitgcmuv > output.txt
498     \end{verbatim}
499    
500     As before, you could build in one directory and make multiple runs of
501     the one experiment:
502     \begin{verbatim}
503     % cd /scratch/exp2
504     % mkdir build
505     % cd build
506     % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
507     -mods=~/MITgcm/verification/exp2/code
508     % make depend
509     % make
510     % cd ../
511     % cp -r ~/MITgcm/verification/exp2/input run2
512     % cd run2
513     % ./mitgcmuv > output.txt
514     \end{verbatim}
515    
516    
517     \subsection{Using \texttt{genmake2}}
518     \label{sect:genmake}
519    
520     To compile the code, first use the program \texttt{genmake2} (located
521     in the \texttt{tools} directory) to generate a Makefile.
522     \texttt{genmake2} is a shell script written to work with all
523     ``sh''--compatible shells including bash v1, bash v2, and Bourne.
524     Internally, \texttt{genmake2} determines the locations of needed
525     files, the compiler, compiler options, libraries, and Unix tools. It
526     relies upon a number of ``optfiles'' located in the
527     \texttt{tools/build\_options} directory.
528    
529     The purpose of the optfiles is to provide all the compilation options
530     for particular ``platforms'' (where ``platform'' roughly means the
531     combination of the hardware and the compiler) and code configurations.
532     Given the combinations of possible compilers and library dependencies
533     ({\it eg.} MPI and NetCDF) there may be numerous optfiles available
534     for a single machine. The naming scheme for the majority of the
535     optfiles shipped with the code is
536     \begin{center}
537     {\bf OS\_HARDWARE\_COMPILER }
538     \end{center}
539     where
540     \begin{description}
541     \item[OS] is the name of the operating system (generally the
542     lower-case output of the {\tt 'uname'} command)
543     \item[HARDWARE] is a string that describes the CPU type and
544     corresponds to output from the {\tt 'uname -m'} command:
545     \begin{description}
546     \item[ia32] is for ``x86'' machines such as i386, i486, i586, i686,
547     and athlon
548     \item[ia64] is for Intel IA64 systems (eg. Itanium, Itanium2)
549     \item[amd64] is AMD x86\_64 systems
550     \item[ppc] is for Mac PowerPC systems
551     \end{description}
552     \item[COMPILER] is the compiler name (generally, the name of the
553     FORTRAN executable)
554     \end{description}
555    
556     In many cases, the default optfiles are sufficient and will result in
557     usable Makefiles. However, for some machines or code configurations,
558     new ``optfiles'' must be written. To create a new optfile, it is
559     generally best to start with one of the defaults and modify it to suit
560     your needs. Like \texttt{genmake2}, the optfiles are all written
561     using a simple ``sh''--compatible syntax. While nearly all variables
562     used within \texttt{genmake2} may be specified in the optfiles, the
563     critical ones that should be defined are:
564    
565     \begin{description}
566     \item[FC] the FORTRAN compiler (executable) to use
567     \item[DEFINES] the command-line DEFINE options passed to the compiler
568     \item[CPP] the C pre-processor to use
569     \item[NOOPTFLAGS] options flags for special files that should not be
570     optimized
571     \end{description}
572    
573     For example, the optfile for a typical Red Hat Linux machine (``ia32''
574     architecture) using the GCC (g77) compiler is
575     \begin{verbatim}
576     FC=g77
577     DEFINES='-D_BYTESWAPIO -DWORDLENGTH=4'
578     CPP='cpp -traditional -P'
579     NOOPTFLAGS='-O0'
580     # For IEEE, use the "-ffloat-store" option
581     if test "x$IEEE" = x ; then
582     FFLAGS='-Wimplicit -Wunused -Wuninitialized'
583     FOPTIM='-O3 -malign-double -funroll-loops'
584     else
585     FFLAGS='-Wimplicit -Wunused -ffloat-store'
586     FOPTIM='-O0 -malign-double'
587     fi
588     \end{verbatim}
589    
590     If you write an optfile for an unrepresented machine or compiler, you
591     are strongly encouraged to submit the optfile to the MITgcm project
592     for inclusion. Please send the file to the
593     \begin{rawhtml} <A href="mail-to:MITgcm-support@mitgcm.org"> \end{rawhtml}
594     \begin{center}
595     MITgcm-support@mitgcm.org
596     \end{center}
597     \begin{rawhtml} </A> \end{rawhtml}
598     mailing list.
599    
600     In addition to the optfiles, \texttt{genmake2} supports a number of
601     helpful command-line options. A complete list of these options can be
602     obtained from:
603     \begin{verbatim}
604     % genmake2 -h
605     \end{verbatim}
606    
607     The most important command-line options are:
608     \begin{description}
609    
610     \item[\texttt{--optfile=/PATH/FILENAME}] specifies the optfile that
611     should be used for a particular build.
612    
613     If no "optfile" is specified (either through the command line or the
614     MITGCM\_OPTFILE environment variable), genmake2 will try to make a
615     reasonable guess from the list provided in {\em
616     tools/build\_options}. The method used for making this guess is
617     to first determine the combination of operating system and hardware
618     (eg. "linux\_ia32") and then find a working FORTRAN compiler within
619     the user's path. When these three items have been identified,
620     genmake2 will try to find an optfile that has a matching name.
621    
622     \item[\texttt{--pdefault='PKG1 PKG2 PKG3 ...'}] specifies the default
623     set of packages to be used. The normal order of precedence for
624     packages is as follows:
625     \begin{enumerate}
626     \item If available, the command line (\texttt{--pdefault}) settings
627     over-rule any others.
628    
629     \item Next, \texttt{genmake2} will look for a file named
630     ``\texttt{packages.conf}'' in the local directory or in any of the
631     directories specified with the \texttt{--mods} option.
632    
633     \item Finally, if neither of the above are available,
634     \texttt{genmake2} will use the \texttt{/pkg/pkg\_default} file.
635     \end{enumerate}
636    
637     \item[\texttt{--pdepend=/PATH/FILENAME}] specifies the dependency file
638     used for packages.
639    
640     If not specified, the default dependency file {\em pkg/pkg\_depend}
641     is used. The syntax for this file is parsed on a line-by-line basis
642     where each line containes either a comment ("\#") or a simple
643     "PKGNAME1 (+|-)PKGNAME2" pairwise rule where the "+" or "-" symbol
644     specifies a "must be used with" or a "must not be used with"
645     relationship, respectively. If no rule is specified, then it is
646     assumed that the two packages are compatible and will function
647     either with or without each other.
648    
649     \item[\texttt{--adof=/path/to/file}] specifies the "adjoint" or
650     automatic differentiation options file to be used. The file is
651     analogous to the ``optfile'' defined above but it specifies
652     information for the AD build process.
653    
654     The default file is located in {\em
655     tools/adjoint\_options/adjoint\_default} and it defines the "TAF"
656     and "TAMC" compilers. An alternate version is also available at
657     {\em tools/adjoint\_options/adjoint\_staf} that selects the newer
658     "STAF" compiler. As with any compilers, it is helpful to have their
659     directories listed in your {\tt \$PATH} environment variable.
660    
661     \item[\texttt{--mods='DIR1 DIR2 DIR3 ...'}] specifies a list of
662     directories containing ``modifications''. These directories contain
663     files with names that may (or may not) exist in the main MITgcm
664     source tree but will be overridden by any identically-named sources
665     within the ``MODS'' directories.
666    
667     The order of precedence for this "name-hiding" is as follows:
668     \begin{itemize}
669     \item ``MODS'' directories (in the order given)
670     \item Packages either explicitly specified or provided by default
671     (in the order given)
672     \item Packages included due to package dependencies (in the order
673     that that package dependencies are parsed)
674     \item The "standard dirs" (which may have been specified by the
675     ``-standarddirs'' option)
676     \end{itemize}
677    
678     \item[\texttt{--mpi}] This option enables certain MPI features (using
679     CPP \texttt{\#define}s) within the code and is necessary for MPI
680     builds (see Section \ref{sect:mpi-build}).
681    
682     \item[\texttt{--make=/path/to/gmake}] Due to the poor handling of
683     soft-links and other bugs common with the \texttt{make} versions
684     provided by commercial Unix vendors, GNU \texttt{make} (sometimes
685     called \texttt{gmake}) should be preferred. This option provides a
686     means for specifying the make executable to be used.
687    
688     \item[\texttt{--bash=/path/to/sh}] On some (usually older UNIX)
689     machines, the ``bash'' shell is unavailable. To run on these
690     systems, \texttt{genmake2} can be invoked using an ``sh'' (that is,
691     a Bourne, POSIX, or compatible) shell. The syntax in these
692     circumstances is:
693     \begin{center}
694     \texttt{\% /bin/sh genmake2 -bash=/bin/sh [...options...]}
695     \end{center}
696     where \texttt{/bin/sh} can be replaced with the full path and name
697     of the desired shell.
698    
699     \end{description}
700    
701    
702     \subsection{Building with MPI}
703     \label{sect:mpi-build}
704    
705     Building MITgcm to use MPI libraries can be complicated due to the
706     variety of different MPI implementations available, their dependencies
707     or interactions with different compilers, and their often ad-hoc
708     locations within file systems. For these reasons, its generally a
709     good idea to start by finding and reading the documentation for your
710     machine(s) and, if necessary, seeking help from your local systems
711     administrator.
712    
713     The steps for building MITgcm with MPI support are:
714     \begin{enumerate}
715    
716     \item Determine the locations of your MPI-enabled compiler and/or MPI
717     libraries and put them into an options file as described in Section
718     \ref{sect:genmake}. One can start with one of the examples in:
719     \begin{rawhtml} <A
720     href="http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm/tools/build_options/">
721     \end{rawhtml}
722     \begin{center}
723     \texttt{MITgcm/tools/build\_options/}
724     \end{center}
725     \begin{rawhtml} </A> \end{rawhtml}
726     such as \texttt{linux\_ia32\_g77+mpi\_cg01} or
727     \texttt{linux\_ia64\_efc+mpi} and then edit it to suit the machine at
728     hand. You may need help from your user guide or local systems
729     administrator to determine the exact location of the MPI libraries.
730     If libraries are not installed, MPI implementations and related
731     tools are available including:
732     \begin{itemize}
733     \item \begin{rawhtml} <A
734     href="http://www-unix.mcs.anl.gov/mpi/mpich/">
735     \end{rawhtml}
736     MPICH
737     \begin{rawhtml} </A> \end{rawhtml}
738    
739     \item \begin{rawhtml} <A
740     href="http://www.lam-mpi.org/">
741     \end{rawhtml}
742     LAM/MPI
743     \begin{rawhtml} </A> \end{rawhtml}
744    
745     \item \begin{rawhtml} <A
746     href="http://www.osc.edu/~pw/mpiexec/">
747     \end{rawhtml}
748     MPIexec
749     \begin{rawhtml} </A> \end{rawhtml}
750     \end{itemize}
751    
752     \item Build the code with the \texttt{genmake2} \texttt{-mpi} option
753     (see Section \ref{sect:genmake}) using commands such as:
754     {\footnotesize \begin{verbatim}
755     % ../../../tools/genmake2 -mods=../code -mpi -of=YOUR_OPTFILE
756     % make depend
757     % make
758     \end{verbatim} }
759    
760     \item Run the code with the appropriate MPI ``run'' or ``exec''
761     program provided with your particular implementation of MPI.
762     Typical MPI packages such as MPICH will use something like:
763     \begin{verbatim}
764     % mpirun -np 4 -machinefile mf ./mitgcmuv
765     \end{verbatim}
766     Sightly more complicated scripts may be needed for many machines
767     since execution of the code may be controlled by both the MPI
768     library and a job scheduling and queueing system such as PBS,
769     LoadLeveller, Condor, or any of a number of similar tools. A few
770     example scripts (those used for our \begin{rawhtml} <A
771     href="http://mitgcm.org/testing.html"> \end{rawhtml}regular
772     verification runs\begin{rawhtml} </A> \end{rawhtml}) are available
773     at:
774     \begin{rawhtml} <A
775     href="http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm_contrib/test_scripts/">
776     \end{rawhtml}
777     {\footnotesize \tt
778     http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm\_contrib/test\_scripts/ }
779     \begin{rawhtml} </A> \end{rawhtml}
780    
781     \end{enumerate}
782    
783     An example of the above process on the MITgcm cluster (``cg01'') using
784     the GNU g77 compiler and the mpich MPI library is:
785    
786     {\footnotesize \begin{verbatim}
787     % cd MITgcm/verification/exp5
788     % mkdir build
789     % cd build
790     % ../../../tools/genmake2 -mpi -mods=../code \
791     -of=../../../tools/build_options/linux_ia32_g77+mpi_cg01
792     % make depend
793     % make
794     % cd ../input
795     % /usr/local/pkg/mpi/mpi-1.2.4..8a-gm-1.5/g77/bin/mpirun.ch_gm \
796     -machinefile mf --gm-kill 5 -v -np 2 ../build/mitgcmuv
797     \end{verbatim} }
798 adcroft 1.4
799 cnh 1.26 \section[Running MITgcm]{Running the model in prognostic mode}
800 adcroft 1.4 \label{sect:runModel}
801 edhill 1.30 \begin{rawhtml}
802     <!-- CMIREDIR:runModel: -->
803     \end{rawhtml}
804 adcroft 1.4
805 edhill 1.31 If compilation finished succesfully (section \ref{sect:buildingCode})
806 edhill 1.23 then an executable called \texttt{mitgcmuv} will now exist in the
807     local directory.
808 adcroft 1.1
809 edhill 1.29 To run the model as a single process (\textit{ie.} not in parallel)
810     simply type:
811 adcroft 1.1 \begin{verbatim}
812 adcroft 1.4 % ./mitgcmuv
813 adcroft 1.1 \end{verbatim}
814 adcroft 1.4 The ``./'' is a safe-guard to make sure you use the local executable
815     in case you have others that exist in your path (surely odd if you
816     do!). The above command will spew out many lines of text output to
817     your screen. This output contains details such as parameter values as
818     well as diagnostics such as mean Kinetic energy, largest CFL number,
819     etc. It is worth keeping this text output with the binary output so we
820 edhill 1.31 normally re-direct the \texttt{stdout} stream as follows:
821 adcroft 1.1 \begin{verbatim}
822 adcroft 1.4 % ./mitgcmuv > output.txt
823 adcroft 1.1 \end{verbatim}
824 edhill 1.29 In the event that the model encounters an error and stops, it is very
825     helpful to include the last few line of this \texttt{output.txt} file
826     along with the (\texttt{stderr}) error message within any bug reports.
827 adcroft 1.1
828 edhill 1.31 For the example experiments in \texttt{verification}, an example of the
829     output is kept in \texttt{results/output.txt} for comparison. You can
830     compare your \texttt{output.txt} with the corresponding one for that
831 edhill 1.29 experiment to check that the set-up works.
832 adcroft 1.1
833    
834    
835 adcroft 1.4 \subsection{Output files}
836 adcroft 1.1
837 edhill 1.31 The model produces various output files and, when using \texttt{mnc},
838     sometimes even directories. Depending upon the I/O package(s)
839     selected at compile time (either \texttt{mdsio} or \texttt{mnc} or
840     both as determined by \texttt{code/packages.conf}) and the run-time
841     flags set (in \texttt{input/data.pkg}), the following output may
842     appear.
843 edhill 1.29
844    
845     \subsubsection{MDSIO output files}
846    
847     The ``traditional'' output files are generated by the \texttt{mdsio}
848     package. At a minimum, the instantaneous ``state'' of the model is
849     written out, which is made of the following files:
850 adcroft 1.1
851     \begin{itemize}
852 edhill 1.34 \item \texttt{U.00000nIter} - zonal component of velocity field (m/s
853     and positive eastward).
854 adcroft 1.1
855 edhill 1.34 \item \texttt{V.00000nIter} - meridional component of velocity field
856     (m/s and positive northward).
857 adcroft 1.1
858 edhill 1.34 \item \texttt{W.00000nIter} - vertical component of velocity field
859     (ocean: m/s and positive upward, atmosphere: Pa/s and positive
860     towards increasing pressure i.e. downward).
861 adcroft 1.1
862 edhill 1.34 \item \texttt{T.00000nIter} - potential temperature (ocean:
863     $^{\circ}\mathrm{C}$, atmosphere: $^{\circ}\mathrm{K}$).
864 adcroft 1.1
865 edhill 1.34 \item \texttt{S.00000nIter} - ocean: salinity (psu), atmosphere: water
866     vapor (g/kg).
867 adcroft 1.1
868 edhill 1.34 \item \texttt{Eta.00000nIter} - ocean: surface elevation (m),
869     atmosphere: surface pressure anomaly (Pa).
870 adcroft 1.1 \end{itemize}
871    
872 edhill 1.31 The chain \texttt{00000nIter} consists of ten figures that specify the
873 edhill 1.34 iteration number at which the output is written out. For example,
874     \texttt{U.0000000300} is the zonal velocity at iteration 300.
875 adcroft 1.1
876     In addition, a ``pickup'' or ``checkpoint'' file called:
877    
878     \begin{itemize}
879 edhill 1.31 \item \texttt{pickup.00000nIter}
880 adcroft 1.1 \end{itemize}
881    
882     is written out. This file represents the state of the model in a condensed
883     form and is used for restarting the integration. If the C-D scheme is used,
884     there is an additional ``pickup'' file:
885    
886     \begin{itemize}
887 edhill 1.31 \item \texttt{pickup\_cd.00000nIter}
888 adcroft 1.1 \end{itemize}
889    
890     containing the D-grid velocity data and that has to be written out as well
891     in order to restart the integration. Rolling checkpoint files are the same
892     as the pickup files but are named differently. Their name contain the chain
893 edhill 1.31 \texttt{ckptA} or \texttt{ckptB} instead of \texttt{00000nIter}. They can be
894 adcroft 1.1 used to restart the model but are overwritten every other time they are
895     output to save disk space during long integrations.
896    
897 edhill 1.29
898    
899     \subsubsection{MNC output files}
900    
901     Unlike the \texttt{mdsio} output, the \texttt{mnc}--generated output
902     is usually (though not necessarily) placed within a subdirectory with
903     a name such as \texttt{mnc\_test\_\${DATE}\_\${SEQ}}. The files
904     within this subdirectory are all in the ``self-describing'' netCDF
905     format and can thus be browsed and/or plotted using tools such as:
906     \begin{itemize}
907 edhill 1.31 \item \texttt{ncdump} is a utility which is typically included
908 edhill 1.29 with every netCDF install:
909     \begin{rawhtml} <A href="http://www.unidata.ucar.edu/packages/netcdf/"> \end{rawhtml}
910     \begin{verbatim}
911 edhill 1.34 http://www.unidata.ucar.edu/packages/netcdf/
912 edhill 1.29 \end{verbatim}
913 edhill 1.31 \begin{rawhtml} </A> \end{rawhtml} and it converts the netCDF
914     binaries into formatted ASCII text files.
915 edhill 1.29
916 edhill 1.31 \item \texttt{ncview} utility is a very convenient and quick way
917 edhill 1.29 to plot netCDF data and it runs on most OSes:
918     \begin{rawhtml} <A href="http://meteora.ucsd.edu/~pierce/ncview_home_page.html"> \end{rawhtml}
919     \begin{verbatim}
920 edhill 1.34 http://meteora.ucsd.edu/~pierce/ncview_home_page.html
921 edhill 1.29 \end{verbatim}
922     \begin{rawhtml} </A> \end{rawhtml}
923    
924     \item MatLAB(c) and other common post-processing environments provide
925     various netCDF interfaces including:
926 edhill 1.34 \begin{rawhtml} <A href="http://mexcdf.sourceforge.net/"> \end{rawhtml}
927     \begin{verbatim}
928     http://mexcdf.sourceforge.net/
929     \end{verbatim}
930     \begin{rawhtml} </A> \end{rawhtml}
931 edhill 1.29 \begin{rawhtml} <A href="http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html"> \end{rawhtml}
932     \begin{verbatim}
933     http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html
934     \end{verbatim}
935     \begin{rawhtml} </A> \end{rawhtml}
936     \end{itemize}
937    
938    
939 adcroft 1.4 \subsection{Looking at the output}
940 adcroft 1.1
941 edhill 1.29 The ``traditional'' or mdsio model data are written according to a
942     ``meta/data'' file format. Each variable is associated with two files
943 edhill 1.31 with suffix names \texttt{.data} and \texttt{.meta}. The
944     \texttt{.data} file contains the data written in binary form
945     (big\_endian by default). The \texttt{.meta} file is a ``header'' file
946 edhill 1.29 that contains information about the size and the structure of the
947 edhill 1.31 \texttt{.data} file. This way of organizing the output is particularly
948 edhill 1.29 useful when running multi-processors calculations. The base version of
949     the model includes a few matlab utilities to read output files written
950     in this format. The matlab scripts are located in the directory
951 edhill 1.31 \texttt{utils/matlab} under the root tree. The script \texttt{rdmds.m}
952 edhill 1.29 reads the data. Look at the comments inside the script to see how to
953     use it.
954 adcroft 1.1
955 adcroft 1.4 Some examples of reading and visualizing some output in {\em Matlab}:
956     \begin{verbatim}
957     % matlab
958     >> H=rdmds('Depth');
959     >> contourf(H');colorbar;
960     >> title('Depth of fluid as used by model');
961    
962     >> eta=rdmds('Eta',10);
963     >> imagesc(eta');axis ij;colorbar;
964     >> title('Surface height at iter=10');
965    
966     >> eta=rdmds('Eta',[0:10:100]);
967     >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end
968     \end{verbatim}
969 adcroft 1.1
970 edhill 1.31 Similar scripts for netCDF output (\texttt{rdmnc.m}) are available and
971     they are described in Section \ref{sec:pkg:mnc}.
972    

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