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1 molod 1.39 % $Header: /u/gcmpack/manual/part3/getting_started.tex,v 1.38 2006/06/28 17:20:51 molod Exp $
2 adcroft 1.2 % $Name: $
3 adcroft 1.1
4 adcroft 1.4 %\section{Getting started}
5 adcroft 1.1
6 molod 1.39 We believe the best way to familiarize yourself with the
7 adcroft 1.4 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
9 molod 1.39 found here as well as a brief description of the model structure
10     directory and the case study examples. Information is also provided
11     here on how to customize the code when you are ready to try implementing
12     the configuration you have in mind. The code and algorithm
13     are described more fully in chapters \ref{chap:discretization} and
14     \ref{chap:sarch}.
15 adcroft 1.4
16     \section{Where to find information}
17     \label{sect:whereToFindInfo}
18 edhill 1.30 \begin{rawhtml}
19     <!-- CMIREDIR:whereToFindInfo: -->
20     \end{rawhtml}
21 adcroft 1.4
22 molod 1.37 There is a web-archived support mailing list for the model that
23 edhill 1.15 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}
26     http://mitgcm.org/mailman/listinfo/mitgcm-support/
27     http://mitgcm.org/pipermail/mitgcm-support/
28     \end{verbatim}
29     \begin{rawhtml} </A> \end{rawhtml}
30 adcroft 1.4
31     \section{Obtaining the code}
32     \label{sect:obtainingCode}
33 edhill 1.30 \begin{rawhtml}
34     <!-- CMIREDIR:obtainingCode: -->
35     \end{rawhtml}
36 adcroft 1.1
37 cnh 1.7 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 edhill 1.14 \begin{rawhtml} <A href=mailto:MITgcm-support@mitgcm.org> \end{rawhtml}
40     MITgcm-support@mitgcm.org
41 cnh 1.7 \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 cnh 1.9 \item Using CVS software. CVS is a freely available source code management
47 cnh 1.7 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 cnh 1.27 \subsection{Method 1 - Checkout from CVS}
66 edhill 1.19 \label{sect:cvs_checkout}
67    
68 adcroft 1.1 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
70     track of your changes. If CVS is not available on your machine, you can also
71     download a tar file.
72    
73 edhill 1.15 Before you can use CVS, the following environment variable(s) should
74     be set within your shell. For a csh or tcsh shell, put the following
75     \begin{verbatim}
76     % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/gcmpack
77     \end{verbatim}
78 edhill 1.31 in your \texttt{.cshrc} or \texttt{.tcshrc} file. For bash or sh
79     shells, put:
80 adcroft 1.1 \begin{verbatim}
81 edhill 1.15 % export CVSROOT=':pserver:cvsanon@mitgcm.org:/u/gcmpack'
82 adcroft 1.6 \end{verbatim}
83 edhill 1.20 in your \texttt{.profile} or \texttt{.bashrc} file.
84 adcroft 1.6
85 edhill 1.15
86     To get MITgcm through CVS, first register with the MITgcm CVS server
87     using command:
88 adcroft 1.6 \begin{verbatim}
89 adcroft 1.1 % cvs login ( CVS password: cvsanon )
90     \end{verbatim}
91 edhill 1.15 You only need to do a ``cvs login'' once.
92 adcroft 1.1
93 edhill 1.15 To obtain the latest sources type:
94     \begin{verbatim}
95     % cvs co MITgcm
96     \end{verbatim}
97     or to get a specific release type:
98 adcroft 1.1 \begin{verbatim}
99 edhill 1.16 % cvs co -P -r checkpoint52i_post MITgcm
100 adcroft 1.1 \end{verbatim}
101 edhill 1.15 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 edhill 1.34 \begin{rawhtml} <A href="http://mitgcm.org/download" target="idontexist"> \end{rawhtml}
106 edhill 1.15 \begin{verbatim}
107 edhill 1.17 http://mitgcm.org/source_code.html
108 edhill 1.15 \end{verbatim}
109     \begin{rawhtml} </A> \end{rawhtml}
110 adcroft 1.1
111 edhill 1.19 As a convenience, the MITgcm CVS server contains aliases which are
112     named subsets of the codebase. These aliases can be especially
113     helpful when used over slow internet connections or on machines with
114     restricted storage space. Table \ref{tab:cvsModules} contains a list
115     of CVS aliases
116     \begin{table}[htb]
117     \centering
118     \begin{tabular}[htb]{|lp{3.25in}|}\hline
119     \textbf{Alias Name} & \textbf{Information (directories) Contained} \\\hline
120     \texttt{MITgcm\_code} & Only the source code -- none of the verification examples. \\
121     \texttt{MITgcm\_verif\_basic}
122     & Source code plus a small set of the verification examples
123     (\texttt{global\_ocean.90x40x15}, \texttt{aim.5l\_cs}, \texttt{hs94.128x64x5},
124     \texttt{front\_relax}, and \texttt{plume\_on\_slope}). \\
125     \texttt{MITgcm\_verif\_atmos} & Source code plus all of the atmospheric examples. \\
126     \texttt{MITgcm\_verif\_ocean} & Source code plus all of the oceanic examples. \\
127     \texttt{MITgcm\_verif\_all} & Source code plus all of the
128     verification examples. \\\hline
129     \end{tabular}
130     \caption{MITgcm CVS Modules}
131     \label{tab:cvsModules}
132     \end{table}
133 edhill 1.15
134 edhill 1.31 The checkout process creates a directory called \texttt{MITgcm}. If
135     the directory \texttt{MITgcm} exists this command updates your code
136 edhill 1.15 based on the repository. Each directory in the source tree contains a
137 edhill 1.31 directory \texttt{CVS}. This information is required by CVS to keep
138 edhill 1.15 track of your file versions with respect to the repository. Don't edit
139 edhill 1.31 the files in \texttt{CVS}! You can also use CVS to download code
140 edhill 1.15 updates. More extensive information on using CVS for maintaining
141     MITgcm code can be found
142 edhill 1.34 \begin{rawhtml} <A href="http://mitgcm.org/usingcvstoget.html" target="idontexist"> \end{rawhtml}
143 cnh 1.7 here
144     \begin{rawhtml} </A> \end{rawhtml}
145     .
146 edhill 1.19 It is important to note that the CVS aliases in Table
147     \ref{tab:cvsModules} cannot be used in conjunction with the CVS
148     \texttt{-d DIRNAME} option. However, the \texttt{MITgcm} directories
149     they create can be changed to a different name following the check-out:
150     \begin{verbatim}
151     % cvs co MITgcm_verif_basic
152     % mv MITgcm MITgcm_verif_basic
153     \end{verbatim}
154 cnh 1.7
155 edhill 1.19 \subsubsection{Upgrading from an earlier version}
156 adcroft 1.12
157     If you already have an earlier version of the code you can ``upgrade''
158     your copy instead of downloading the entire repository again. First,
159     ``cd'' (change directory) to the top of your working copy:
160     \begin{verbatim}
161     % cd MITgcm
162     \end{verbatim}
163 edhill 1.15 and then issue the cvs update command such as:
164 adcroft 1.12 \begin{verbatim}
165 edhill 1.16 % cvs -q update -r checkpoint52i_post -d -P
166 adcroft 1.12 \end{verbatim}
167 edhill 1.16 This will update the ``tag'' to ``checkpoint52i\_post'', add any new
168 adcroft 1.12 directories (-d) and remove any empty directories (-P). The -q option
169     means be quiet which will reduce the number of messages you'll see in
170     the terminal. If you have modified the code prior to upgrading, CVS
171     will try to merge your changes with the upgrades. If there is a
172     conflict between your modifications and the upgrade, it will report
173     that file with a ``C'' in front, e.g.:
174     \begin{verbatim}
175     C model/src/ini_parms.F
176     \end{verbatim}
177     If the list of conflicts scrolled off the screen, you can re-issue the
178     cvs update command and it will report the conflicts. Conflicts are
179 edhill 1.15 indicated in the code by the delimites ``$<<<<<<<$'', ``======='' and
180     ``$>>>>>>>$''. For example,
181 edhill 1.17 {\small
182 adcroft 1.12 \begin{verbatim}
183     <<<<<<< ini_parms.F
184     & bottomDragLinear,myOwnBottomDragCoefficient,
185     =======
186     & bottomDragLinear,bottomDragQuadratic,
187     >>>>>>> 1.18
188     \end{verbatim}
189 edhill 1.17 }
190 adcroft 1.12 means that you added ``myOwnBottomDragCoefficient'' to a namelist at
191     the same time and place that we added ``bottomDragQuadratic''. You
192     need to resolve this conflict and in this case the line should be
193     changed to:
194 edhill 1.17 {\small
195 adcroft 1.12 \begin{verbatim}
196     & bottomDragLinear,bottomDragQuadratic,myOwnBottomDragCoefficient,
197     \end{verbatim}
198 edhill 1.17 }
199 edhill 1.15 and the lines with the delimiters ($<<<<<<$,======,$>>>>>>$) be deleted.
200 adcroft 1.12 Unless you are making modifications which exactly parallel
201     developments we make, these types of conflicts should be rare.
202    
203     \paragraph*{Upgrading to the current pre-release version}
204    
205     We don't make a ``release'' for every little patch and bug fix in
206     order to keep the frequency of upgrades to a minimum. However, if you
207     have run into a problem for which ``we have already fixed in the
208     latest code'' and we haven't made a ``tag'' or ``release'' since that
209     patch then you'll need to get the latest code:
210     \begin{verbatim}
211     % cvs -q update -A -d -P
212     \end{verbatim}
213     Unlike, the ``check-out'' and ``update'' procedures above, there is no
214     ``tag'' or release name. The -A tells CVS to upgrade to the
215     very latest version. As a rule, we don't recommend this since you
216     might upgrade while we are in the processes of checking in the code so
217     that you may only have part of a patch. Using this method of updating
218     also means we can't tell what version of the code you are working
219     with. So please be sure you understand what you're doing.
220    
221 molod 1.37 \subsection{Method 2 - Tar file download}
222     \label{sect:conventionalDownload}
223    
224     If you do not have CVS on your system, you can download the model as a
225     tar file from the web site at:
226     \begin{rawhtml} <A href=http://mitgcm.org/download target="idontexist"> \end{rawhtml}
227     \begin{verbatim}
228     http://mitgcm.org/download/
229     \end{verbatim}
230     \begin{rawhtml} </A> \end{rawhtml}
231     The tar file still contains CVS information which we urge you not to
232     delete; even if you do not use CVS yourself the information can help
233     us if you should need to send us your copy of the code. If a recent
234     tar file does not exist, then please contact the developers through
235     the
236     \begin{rawhtml} <A href="mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
237     MITgcm-support@mitgcm.org
238     \begin{rawhtml} </A> \end{rawhtml}
239     mailing list.
240    
241 adcroft 1.4 \section{Model and directory structure}
242 edhill 1.30 \begin{rawhtml}
243     <!-- CMIREDIR:directory_structure: -->
244     \end{rawhtml}
245 adcroft 1.1
246 adcroft 1.12 The ``numerical'' model is contained within a execution environment
247     support wrapper. This wrapper is designed to provide a general
248     framework for grid-point models. MITgcmUV is a specific numerical
249     model that uses the framework. Under this structure the model is split
250     into execution environment support code and conventional numerical
251     model code. The execution environment support code is held under the
252 edhill 1.31 \texttt{eesupp} directory. The grid point model code is held under the
253     \texttt{model} directory. Code execution actually starts in the
254     \texttt{eesupp} routines and not in the \texttt{model} routines. For
255     this reason the top-level \texttt{MAIN.F} is in the
256     \texttt{eesupp/src} directory. In general, end-users should not need
257 edhill 1.17 to worry about this level. The top-level routine for the numerical
258 edhill 1.31 part of the code is in \texttt{model/src/THE\_MODEL\_MAIN.F}. Here is
259 edhill 1.17 a brief description of the directory structure of the model under the
260     root tree (a detailed description is given in section 3: Code
261     structure).
262 adcroft 1.1
263     \begin{itemize}
264    
265 edhill 1.31 \item \texttt{doc}: contains brief documentation notes.
266    
267     \item \texttt{eesupp}: contains the execution environment source code.
268     Also subdivided into two subdirectories \texttt{inc} and
269     \texttt{src}.
270 edhill 1.17
271 edhill 1.31 \item \texttt{model}: this directory contains the main source code.
272     Also subdivided into two subdirectories \texttt{inc} and
273     \texttt{src}.
274 edhill 1.17
275 edhill 1.31 \item \texttt{pkg}: contains the source code for the packages. Each
276     package corresponds to a subdirectory. For example, \texttt{gmredi}
277 edhill 1.17 contains the code related to the Gent-McWilliams/Redi scheme,
278 edhill 1.31 \texttt{aim} the code relative to the atmospheric intermediate
279 molod 1.37 physics. The packages are described in detail in chapter \ref{chap.packagesI}.
280 edhill 1.17
281 edhill 1.31 \item \texttt{tools}: this directory contains various useful tools.
282     For example, \texttt{genmake2} is a script written in csh (C-shell)
283 edhill 1.17 that should be used to generate your makefile. The directory
284 edhill 1.31 \texttt{adjoint} contains the makefile specific to the Tangent
285 edhill 1.17 linear and Adjoint Compiler (TAMC) that generates the adjoint code.
286 molod 1.37 The latter is described in detail in part \ref{chap.ecco}.
287     This directory also contains the subdirectory build\_options, which
288     contains the `optfiles' with the compiler options for the different
289     compilers and machines that can run MITgcm.
290 edhill 1.17
291 edhill 1.31 \item \texttt{utils}: this directory contains various utilities. The
292     subdirectory \texttt{knudsen2} contains code and a makefile that
293 edhill 1.17 compute coefficients of the polynomial approximation to the knudsen
294     formula for an ocean nonlinear equation of state. The
295 edhill 1.31 \texttt{matlab} subdirectory contains matlab scripts for reading
296     model output directly into matlab. \texttt{scripts} contains C-shell
297 edhill 1.17 post-processing scripts for joining processor-based and tiled-based
298 molod 1.37 model output. The subdirectory exch2 contains the code needed for
299     the exch2 package to work with different combinations of domain
300     decompositions.
301 edhill 1.17
302 edhill 1.31 \item \texttt{verification}: this directory contains the model
303 edhill 1.17 examples. See section \ref{sect:modelExamples}.
304 adcroft 1.1
305 molod 1.37 \item \texttt{jobs}: contains sample job scripts for running MITgcm.
306    
307     \item \texttt{lsopt}: Line search code used for optimization.
308    
309     \item \texttt{optim}: Interface between MITgcm and line search code.
310    
311 adcroft 1.1 \end{itemize}
312    
313 cnh 1.26 \section[Building MITgcm]{Building the code}
314 adcroft 1.4 \label{sect:buildingCode}
315 edhill 1.30 \begin{rawhtml}
316     <!-- CMIREDIR:buildingCode: -->
317     \end{rawhtml}
318 adcroft 1.4
319 edhill 1.31 To compile the code, we use the \texttt{make} program. This uses a
320     file (\texttt{Makefile}) that allows us to pre-process source files,
321     specify compiler and optimization options and also figures out any
322     file dependencies. We supply a script (\texttt{genmake2}), described
323     in section \ref{sect:genmake}, that automatically creates the
324     \texttt{Makefile} for you. You then need to build the dependencies and
325 edhill 1.16 compile the code.
326 adcroft 1.4
327 edhill 1.31 As an example, assume that you want to build and run experiment
328     \texttt{verification/exp2}. The are multiple ways and places to
329 edhill 1.16 actually do this but here let's build the code in
330 edhill 1.31 \texttt{verification/exp2/build}:
331 adcroft 1.4 \begin{verbatim}
332 edhill 1.31 % cd verification/exp2/build
333 adcroft 1.4 \end{verbatim}
334 edhill 1.31 First, build the \texttt{Makefile}:
335 adcroft 1.4 \begin{verbatim}
336 edhill 1.16 % ../../../tools/genmake2 -mods=../code
337 adcroft 1.4 \end{verbatim}
338 edhill 1.31 The command line option tells \texttt{genmake} to override model source
339     code with any files in the directory \texttt{../code/}.
340 adcroft 1.4
341 edhill 1.31 On many systems, the \texttt{genmake2} program will be able to
342 edhill 1.16 automatically recognize the hardware, find compilers and other tools
343 edhill 1.31 within the user's path (``\texttt{echo \$PATH}''), and then choose an
344 edhill 1.29 appropriate set of options from the files (``optfiles'') contained in
345 edhill 1.31 the \texttt{tools/build\_options} directory. Under some
346     circumstances, a user may have to create a new ``optfile'' in order to
347     specify the exact combination of compiler, compiler flags, libraries,
348     and other options necessary to build a particular configuration of
349     MITgcm. In such cases, it is generally helpful to read the existing
350     ``optfiles'' and mimic their syntax.
351 edhill 1.16
352     Through the MITgcm-support list, the MITgcm developers are willing to
353     provide help writing or modifing ``optfiles''. And we encourage users
354     to post new ``optfiles'' (particularly ones for new machines or
355 edhill 1.17 architectures) to the
356 edhill 1.34 \begin{rawhtml} <A href="mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
357 edhill 1.17 MITgcm-support@mitgcm.org
358     \begin{rawhtml} </A> \end{rawhtml}
359     list.
360 edhill 1.16
361 edhill 1.31 To specify an optfile to \texttt{genmake2}, the syntax is:
362 adcroft 1.4 \begin{verbatim}
363 edhill 1.16 % ../../../tools/genmake2 -mods=../code -of /path/to/optfile
364 adcroft 1.4 \end{verbatim}
365    
366 edhill 1.31 Once a \texttt{Makefile} has been generated, we create the
367     dependencies with the command:
368 adcroft 1.4 \begin{verbatim}
369     % make depend
370     \end{verbatim}
371 edhill 1.31 This modifies the \texttt{Makefile} by attaching a (usually, long)
372     list of files upon which other files depend. The purpose of this is to
373     reduce re-compilation if and when you start to modify the code. The
374     {\tt make depend} command also creates links from the model source to
375     this directory. It is important to note that the {\tt make depend}
376     stage will occasionally produce warnings or errors since the
377     dependency parsing tool is unable to find all of the necessary header
378     files (\textit{eg.} \texttt{netcdf.inc}). In these circumstances, it
379     is usually OK to ignore the warnings/errors and proceed to the next
380     step.
381 adcroft 1.1
382 edhill 1.31 Next one can compile the code using:
383 adcroft 1.4 \begin{verbatim}
384     % make
385     \end{verbatim}
386 edhill 1.31 The {\tt make} command creates an executable called \texttt{mitgcmuv}.
387 edhill 1.16 Additional make ``targets'' are defined within the makefile to aid in
388 edhill 1.31 the production of adjoint and other versions of MITgcm. On SMP
389     (shared multi-processor) systems, the build process can often be sped
390     up appreciably using the command:
391     \begin{verbatim}
392     % make -j 2
393     \end{verbatim}
394     where the ``2'' can be replaced with a number that corresponds to the
395     number of CPUs available.
396 adcroft 1.4
397     Now you are ready to run the model. General instructions for doing so are
398 edhill 1.31 given in section \ref{sect:runModel}. Here, we can run the model by
399     first creating links to all the input files:
400     \begin{verbatim}
401     ln -s ../input/* .
402     \end{verbatim}
403     and then calling the executable with:
404 adcroft 1.4 \begin{verbatim}
405     ./mitgcmuv > output.txt
406     \end{verbatim}
407 edhill 1.31 where we are re-directing the stream of text output to the file
408     \texttt{output.txt}.
409 adcroft 1.4
410 molod 1.35 \subsection{Building/compiling the code elsewhere}
411    
412     In the example above (section \ref{sect:buildingCode}) we built the
413     executable in the {\em input} directory of the experiment for
414     convenience. You can also configure and compile the code in other
415     locations, for example on a scratch disk with out having to copy the
416     entire source tree. The only requirement to do so is you have {\tt
417     genmake2} in your path or you know the absolute path to {\tt
418     genmake2}.
419    
420     The following sections outline some possible methods of organizing
421     your source and data.
422    
423     \subsubsection{Building from the {\em ../code directory}}
424    
425     This is just as simple as building in the {\em input/} directory:
426     \begin{verbatim}
427     % cd verification/exp2/code
428     % ../../../tools/genmake2
429     % make depend
430     % make
431     \end{verbatim}
432     However, to run the model the executable ({\em mitgcmuv}) and input
433     files must be in the same place. If you only have one calculation to make:
434     \begin{verbatim}
435     % cd ../input
436     % cp ../code/mitgcmuv ./
437     % ./mitgcmuv > output.txt
438     \end{verbatim}
439     or if you will be making multiple runs with the same executable:
440     \begin{verbatim}
441     % cd ../
442     % cp -r input run1
443     % cp code/mitgcmuv run1
444     % cd run1
445     % ./mitgcmuv > output.txt
446     \end{verbatim}
447    
448     \subsubsection{Building from a new directory}
449    
450     Since the {\em input} directory contains input files it is often more
451     useful to keep {\em input} pristine and build in a new directory
452     within {\em verification/exp2/}:
453     \begin{verbatim}
454     % cd verification/exp2
455     % mkdir build
456     % cd build
457     % ../../../tools/genmake2 -mods=../code
458     % make depend
459     % make
460     \end{verbatim}
461     This builds the code exactly as before but this time you need to copy
462     either the executable or the input files or both in order to run the
463     model. For example,
464     \begin{verbatim}
465     % cp ../input/* ./
466     % ./mitgcmuv > output.txt
467     \end{verbatim}
468     or if you tend to make multiple runs with the same executable then
469     running in a new directory each time might be more appropriate:
470     \begin{verbatim}
471     % cd ../
472     % mkdir run1
473     % cp build/mitgcmuv run1/
474     % cp input/* run1/
475     % cd run1
476     % ./mitgcmuv > output.txt
477     \end{verbatim}
478    
479     \subsubsection{Building on a scratch disk}
480    
481     Model object files and output data can use up large amounts of disk
482     space so it is often the case that you will be operating on a large
483     scratch disk. Assuming the model source is in {\em ~/MITgcm} then the
484     following commands will build the model in {\em /scratch/exp2-run1}:
485     \begin{verbatim}
486     % cd /scratch/exp2-run1
487     % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
488     -mods=~/MITgcm/verification/exp2/code
489     % make depend
490     % make
491     \end{verbatim}
492     To run the model here, you'll need the input files:
493     \begin{verbatim}
494     % cp ~/MITgcm/verification/exp2/input/* ./
495     % ./mitgcmuv > output.txt
496     \end{verbatim}
497    
498     As before, you could build in one directory and make multiple runs of
499     the one experiment:
500     \begin{verbatim}
501     % cd /scratch/exp2
502     % mkdir build
503     % cd build
504     % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
505     -mods=~/MITgcm/verification/exp2/code
506     % make depend
507     % make
508     % cd ../
509     % cp -r ~/MITgcm/verification/exp2/input run2
510     % cd run2
511     % ./mitgcmuv > output.txt
512     \end{verbatim}
513    
514    
515     \subsection{Using \texttt{genmake2}}
516     \label{sect:genmake}
517    
518     To compile the code, first use the program \texttt{genmake2} (located
519     in the \texttt{tools} directory) to generate a Makefile.
520     \texttt{genmake2} is a shell script written to work with all
521     ``sh''--compatible shells including bash v1, bash v2, and Bourne.
522     Internally, \texttt{genmake2} determines the locations of needed
523     files, the compiler, compiler options, libraries, and Unix tools. It
524     relies upon a number of ``optfiles'' located in the
525     \texttt{tools/build\_options} directory.
526    
527     The purpose of the optfiles is to provide all the compilation options
528     for particular ``platforms'' (where ``platform'' roughly means the
529     combination of the hardware and the compiler) and code configurations.
530     Given the combinations of possible compilers and library dependencies
531     ({\it eg.} MPI and NetCDF) there may be numerous optfiles available
532     for a single machine. The naming scheme for the majority of the
533     optfiles shipped with the code is
534     \begin{center}
535     {\bf OS\_HARDWARE\_COMPILER }
536     \end{center}
537     where
538     \begin{description}
539     \item[OS] is the name of the operating system (generally the
540     lower-case output of the {\tt 'uname'} command)
541     \item[HARDWARE] is a string that describes the CPU type and
542     corresponds to output from the {\tt 'uname -m'} command:
543     \begin{description}
544     \item[ia32] is for ``x86'' machines such as i386, i486, i586, i686,
545     and athlon
546     \item[ia64] is for Intel IA64 systems (eg. Itanium, Itanium2)
547     \item[amd64] is AMD x86\_64 systems
548     \item[ppc] is for Mac PowerPC systems
549     \end{description}
550     \item[COMPILER] is the compiler name (generally, the name of the
551     FORTRAN executable)
552     \end{description}
553    
554     In many cases, the default optfiles are sufficient and will result in
555     usable Makefiles. However, for some machines or code configurations,
556     new ``optfiles'' must be written. To create a new optfile, it is
557     generally best to start with one of the defaults and modify it to suit
558     your needs. Like \texttt{genmake2}, the optfiles are all written
559     using a simple ``sh''--compatible syntax. While nearly all variables
560     used within \texttt{genmake2} may be specified in the optfiles, the
561     critical ones that should be defined are:
562    
563     \begin{description}
564     \item[FC] the FORTRAN compiler (executable) to use
565     \item[DEFINES] the command-line DEFINE options passed to the compiler
566     \item[CPP] the C pre-processor to use
567     \item[NOOPTFLAGS] options flags for special files that should not be
568     optimized
569     \end{description}
570    
571     For example, the optfile for a typical Red Hat Linux machine (``ia32''
572     architecture) using the GCC (g77) compiler is
573     \begin{verbatim}
574     FC=g77
575     DEFINES='-D_BYTESWAPIO -DWORDLENGTH=4'
576     CPP='cpp -traditional -P'
577     NOOPTFLAGS='-O0'
578     # For IEEE, use the "-ffloat-store" option
579     if test "x$IEEE" = x ; then
580     FFLAGS='-Wimplicit -Wunused -Wuninitialized'
581     FOPTIM='-O3 -malign-double -funroll-loops'
582     else
583     FFLAGS='-Wimplicit -Wunused -ffloat-store'
584     FOPTIM='-O0 -malign-double'
585     fi
586     \end{verbatim}
587    
588     If you write an optfile for an unrepresented machine or compiler, you
589     are strongly encouraged to submit the optfile to the MITgcm project
590     for inclusion. Please send the file to the
591     \begin{rawhtml} <A href="mail-to:MITgcm-support@mitgcm.org"> \end{rawhtml}
592     \begin{center}
593     MITgcm-support@mitgcm.org
594     \end{center}
595     \begin{rawhtml} </A> \end{rawhtml}
596     mailing list.
597    
598     In addition to the optfiles, \texttt{genmake2} supports a number of
599     helpful command-line options. A complete list of these options can be
600     obtained from:
601     \begin{verbatim}
602     % genmake2 -h
603     \end{verbatim}
604    
605     The most important command-line options are:
606     \begin{description}
607    
608     \item[\texttt{--optfile=/PATH/FILENAME}] specifies the optfile that
609     should be used for a particular build.
610    
611     If no "optfile" is specified (either through the command line or the
612     MITGCM\_OPTFILE environment variable), genmake2 will try to make a
613     reasonable guess from the list provided in {\em
614     tools/build\_options}. The method used for making this guess is
615     to first determine the combination of operating system and hardware
616     (eg. "linux\_ia32") and then find a working FORTRAN compiler within
617     the user's path. When these three items have been identified,
618     genmake2 will try to find an optfile that has a matching name.
619    
620     \item[\texttt{--pdefault='PKG1 PKG2 PKG3 ...'}] specifies the default
621     set of packages to be used. The normal order of precedence for
622     packages is as follows:
623     \begin{enumerate}
624     \item If available, the command line (\texttt{--pdefault}) settings
625     over-rule any others.
626    
627     \item Next, \texttt{genmake2} will look for a file named
628     ``\texttt{packages.conf}'' in the local directory or in any of the
629     directories specified with the \texttt{--mods} option.
630    
631     \item Finally, if neither of the above are available,
632     \texttt{genmake2} will use the \texttt{/pkg/pkg\_default} file.
633     \end{enumerate}
634    
635     \item[\texttt{--pdepend=/PATH/FILENAME}] specifies the dependency file
636     used for packages.
637    
638     If not specified, the default dependency file {\em pkg/pkg\_depend}
639     is used. The syntax for this file is parsed on a line-by-line basis
640     where each line containes either a comment ("\#") or a simple
641     "PKGNAME1 (+|-)PKGNAME2" pairwise rule where the "+" or "-" symbol
642     specifies a "must be used with" or a "must not be used with"
643     relationship, respectively. If no rule is specified, then it is
644     assumed that the two packages are compatible and will function
645     either with or without each other.
646    
647     \item[\texttt{--adof=/path/to/file}] specifies the "adjoint" or
648     automatic differentiation options file to be used. The file is
649     analogous to the ``optfile'' defined above but it specifies
650     information for the AD build process.
651    
652     The default file is located in {\em
653     tools/adjoint\_options/adjoint\_default} and it defines the "TAF"
654     and "TAMC" compilers. An alternate version is also available at
655     {\em tools/adjoint\_options/adjoint\_staf} that selects the newer
656     "STAF" compiler. As with any compilers, it is helpful to have their
657     directories listed in your {\tt \$PATH} environment variable.
658    
659     \item[\texttt{--mods='DIR1 DIR2 DIR3 ...'}] specifies a list of
660     directories containing ``modifications''. These directories contain
661     files with names that may (or may not) exist in the main MITgcm
662     source tree but will be overridden by any identically-named sources
663     within the ``MODS'' directories.
664    
665     The order of precedence for this "name-hiding" is as follows:
666     \begin{itemize}
667     \item ``MODS'' directories (in the order given)
668     \item Packages either explicitly specified or provided by default
669     (in the order given)
670     \item Packages included due to package dependencies (in the order
671     that that package dependencies are parsed)
672     \item The "standard dirs" (which may have been specified by the
673     ``-standarddirs'' option)
674     \end{itemize}
675    
676     \item[\texttt{--mpi}] This option enables certain MPI features (using
677     CPP \texttt{\#define}s) within the code and is necessary for MPI
678     builds (see Section \ref{sect:mpi-build}).
679    
680     \item[\texttt{--make=/path/to/gmake}] Due to the poor handling of
681     soft-links and other bugs common with the \texttt{make} versions
682     provided by commercial Unix vendors, GNU \texttt{make} (sometimes
683     called \texttt{gmake}) should be preferred. This option provides a
684     means for specifying the make executable to be used.
685    
686     \item[\texttt{--bash=/path/to/sh}] On some (usually older UNIX)
687     machines, the ``bash'' shell is unavailable. To run on these
688     systems, \texttt{genmake2} can be invoked using an ``sh'' (that is,
689     a Bourne, POSIX, or compatible) shell. The syntax in these
690     circumstances is:
691     \begin{center}
692     \texttt{\% /bin/sh genmake2 -bash=/bin/sh [...options...]}
693     \end{center}
694     where \texttt{/bin/sh} can be replaced with the full path and name
695     of the desired shell.
696    
697     \end{description}
698    
699    
700     \subsection{Building with MPI}
701     \label{sect:mpi-build}
702    
703     Building MITgcm to use MPI libraries can be complicated due to the
704     variety of different MPI implementations available, their dependencies
705     or interactions with different compilers, and their often ad-hoc
706     locations within file systems. For these reasons, its generally a
707     good idea to start by finding and reading the documentation for your
708     machine(s) and, if necessary, seeking help from your local systems
709     administrator.
710    
711     The steps for building MITgcm with MPI support are:
712     \begin{enumerate}
713    
714     \item Determine the locations of your MPI-enabled compiler and/or MPI
715     libraries and put them into an options file as described in Section
716     \ref{sect:genmake}. One can start with one of the examples in:
717     \begin{rawhtml} <A
718     href="http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm/tools/build_options/">
719     \end{rawhtml}
720     \begin{center}
721     \texttt{MITgcm/tools/build\_options/}
722     \end{center}
723     \begin{rawhtml} </A> \end{rawhtml}
724     such as \texttt{linux\_ia32\_g77+mpi\_cg01} or
725     \texttt{linux\_ia64\_efc+mpi} and then edit it to suit the machine at
726     hand. You may need help from your user guide or local systems
727     administrator to determine the exact location of the MPI libraries.
728     If libraries are not installed, MPI implementations and related
729     tools are available including:
730     \begin{itemize}
731     \item \begin{rawhtml} <A
732     href="http://www-unix.mcs.anl.gov/mpi/mpich/">
733     \end{rawhtml}
734     MPICH
735     \begin{rawhtml} </A> \end{rawhtml}
736    
737     \item \begin{rawhtml} <A
738     href="http://www.lam-mpi.org/">
739     \end{rawhtml}
740     LAM/MPI
741     \begin{rawhtml} </A> \end{rawhtml}
742    
743     \item \begin{rawhtml} <A
744     href="http://www.osc.edu/~pw/mpiexec/">
745     \end{rawhtml}
746     MPIexec
747     \begin{rawhtml} </A> \end{rawhtml}
748     \end{itemize}
749    
750     \item Build the code with the \texttt{genmake2} \texttt{-mpi} option
751     (see Section \ref{sect:genmake}) using commands such as:
752     {\footnotesize \begin{verbatim}
753     % ../../../tools/genmake2 -mods=../code -mpi -of=YOUR_OPTFILE
754     % make depend
755     % make
756     \end{verbatim} }
757    
758     \item Run the code with the appropriate MPI ``run'' or ``exec''
759     program provided with your particular implementation of MPI.
760     Typical MPI packages such as MPICH will use something like:
761     \begin{verbatim}
762     % mpirun -np 4 -machinefile mf ./mitgcmuv
763     \end{verbatim}
764     Sightly more complicated scripts may be needed for many machines
765     since execution of the code may be controlled by both the MPI
766     library and a job scheduling and queueing system such as PBS,
767     LoadLeveller, Condor, or any of a number of similar tools. A few
768     example scripts (those used for our \begin{rawhtml} <A
769     href="http://mitgcm.org/testing.html"> \end{rawhtml}regular
770     verification runs\begin{rawhtml} </A> \end{rawhtml}) are available
771     at:
772     \begin{rawhtml} <A
773     href="http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm_contrib/test_scripts/">
774     \end{rawhtml}
775     {\footnotesize \tt
776     http://mitgcm.org/cgi-bin/viewcvs.cgi/MITgcm\_contrib/test\_scripts/ }
777     \begin{rawhtml} </A> \end{rawhtml}
778    
779     \end{enumerate}
780    
781     An example of the above process on the MITgcm cluster (``cg01'') using
782     the GNU g77 compiler and the mpich MPI library is:
783    
784     {\footnotesize \begin{verbatim}
785     % cd MITgcm/verification/exp5
786     % mkdir build
787     % cd build
788     % ../../../tools/genmake2 -mpi -mods=../code \
789     -of=../../../tools/build_options/linux_ia32_g77+mpi_cg01
790     % make depend
791     % make
792     % cd ../input
793     % /usr/local/pkg/mpi/mpi-1.2.4..8a-gm-1.5/g77/bin/mpirun.ch_gm \
794     -machinefile mf --gm-kill 5 -v -np 2 ../build/mitgcmuv
795     \end{verbatim} }
796 adcroft 1.4
797 cnh 1.26 \section[Running MITgcm]{Running the model in prognostic mode}
798 adcroft 1.4 \label{sect:runModel}
799 edhill 1.30 \begin{rawhtml}
800     <!-- CMIREDIR:runModel: -->
801     \end{rawhtml}
802 adcroft 1.4
803 edhill 1.31 If compilation finished succesfully (section \ref{sect:buildingCode})
804 edhill 1.23 then an executable called \texttt{mitgcmuv} will now exist in the
805     local directory.
806 adcroft 1.1
807 edhill 1.29 To run the model as a single process (\textit{ie.} not in parallel)
808     simply type:
809 adcroft 1.1 \begin{verbatim}
810 adcroft 1.4 % ./mitgcmuv
811 adcroft 1.1 \end{verbatim}
812 adcroft 1.4 The ``./'' is a safe-guard to make sure you use the local executable
813     in case you have others that exist in your path (surely odd if you
814     do!). The above command will spew out many lines of text output to
815     your screen. This output contains details such as parameter values as
816     well as diagnostics such as mean Kinetic energy, largest CFL number,
817     etc. It is worth keeping this text output with the binary output so we
818 edhill 1.31 normally re-direct the \texttt{stdout} stream as follows:
819 adcroft 1.1 \begin{verbatim}
820 adcroft 1.4 % ./mitgcmuv > output.txt
821 adcroft 1.1 \end{verbatim}
822 edhill 1.29 In the event that the model encounters an error and stops, it is very
823     helpful to include the last few line of this \texttt{output.txt} file
824     along with the (\texttt{stderr}) error message within any bug reports.
825 adcroft 1.1
826 edhill 1.31 For the example experiments in \texttt{verification}, an example of the
827     output is kept in \texttt{results/output.txt} for comparison. You can
828     compare your \texttt{output.txt} with the corresponding one for that
829 edhill 1.29 experiment to check that the set-up works.
830 adcroft 1.1
831    
832    
833 adcroft 1.4 \subsection{Output files}
834 adcroft 1.1
835 edhill 1.31 The model produces various output files and, when using \texttt{mnc},
836     sometimes even directories. Depending upon the I/O package(s)
837     selected at compile time (either \texttt{mdsio} or \texttt{mnc} or
838     both as determined by \texttt{code/packages.conf}) and the run-time
839     flags set (in \texttt{input/data.pkg}), the following output may
840     appear.
841 edhill 1.29
842    
843     \subsubsection{MDSIO output files}
844    
845     The ``traditional'' output files are generated by the \texttt{mdsio}
846     package. At a minimum, the instantaneous ``state'' of the model is
847     written out, which is made of the following files:
848 adcroft 1.1
849     \begin{itemize}
850 edhill 1.34 \item \texttt{U.00000nIter} - zonal component of velocity field (m/s
851     and positive eastward).
852 adcroft 1.1
853 edhill 1.34 \item \texttt{V.00000nIter} - meridional component of velocity field
854     (m/s and positive northward).
855 adcroft 1.1
856 edhill 1.34 \item \texttt{W.00000nIter} - vertical component of velocity field
857     (ocean: m/s and positive upward, atmosphere: Pa/s and positive
858     towards increasing pressure i.e. downward).
859 adcroft 1.1
860 edhill 1.34 \item \texttt{T.00000nIter} - potential temperature (ocean:
861     $^{\circ}\mathrm{C}$, atmosphere: $^{\circ}\mathrm{K}$).
862 adcroft 1.1
863 edhill 1.34 \item \texttt{S.00000nIter} - ocean: salinity (psu), atmosphere: water
864     vapor (g/kg).
865 adcroft 1.1
866 edhill 1.34 \item \texttt{Eta.00000nIter} - ocean: surface elevation (m),
867     atmosphere: surface pressure anomaly (Pa).
868 adcroft 1.1 \end{itemize}
869    
870 edhill 1.31 The chain \texttt{00000nIter} consists of ten figures that specify the
871 edhill 1.34 iteration number at which the output is written out. For example,
872     \texttt{U.0000000300} is the zonal velocity at iteration 300.
873 adcroft 1.1
874     In addition, a ``pickup'' or ``checkpoint'' file called:
875    
876     \begin{itemize}
877 edhill 1.31 \item \texttt{pickup.00000nIter}
878 adcroft 1.1 \end{itemize}
879    
880     is written out. This file represents the state of the model in a condensed
881     form and is used for restarting the integration. If the C-D scheme is used,
882     there is an additional ``pickup'' file:
883    
884     \begin{itemize}
885 edhill 1.31 \item \texttt{pickup\_cd.00000nIter}
886 adcroft 1.1 \end{itemize}
887    
888     containing the D-grid velocity data and that has to be written out as well
889     in order to restart the integration. Rolling checkpoint files are the same
890     as the pickup files but are named differently. Their name contain the chain
891 edhill 1.31 \texttt{ckptA} or \texttt{ckptB} instead of \texttt{00000nIter}. They can be
892 adcroft 1.1 used to restart the model but are overwritten every other time they are
893     output to save disk space during long integrations.
894    
895 edhill 1.29 \subsubsection{MNC output files}
896    
897     Unlike the \texttt{mdsio} output, the \texttt{mnc}--generated output
898     is usually (though not necessarily) placed within a subdirectory with
899 molod 1.38 a name such as \texttt{mnc\_test\_\${DATE}\_\${SEQ}}.
900 edhill 1.29
901 adcroft 1.4 \subsection{Looking at the output}
902 adcroft 1.1
903 edhill 1.29 The ``traditional'' or mdsio model data are written according to a
904     ``meta/data'' file format. Each variable is associated with two files
905 edhill 1.31 with suffix names \texttt{.data} and \texttt{.meta}. The
906     \texttt{.data} file contains the data written in binary form
907     (big\_endian by default). The \texttt{.meta} file is a ``header'' file
908 edhill 1.29 that contains information about the size and the structure of the
909 edhill 1.31 \texttt{.data} file. This way of organizing the output is particularly
910 edhill 1.29 useful when running multi-processors calculations. The base version of
911     the model includes a few matlab utilities to read output files written
912     in this format. The matlab scripts are located in the directory
913 edhill 1.31 \texttt{utils/matlab} under the root tree. The script \texttt{rdmds.m}
914 edhill 1.29 reads the data. Look at the comments inside the script to see how to
915     use it.
916 adcroft 1.1
917 adcroft 1.4 Some examples of reading and visualizing some output in {\em Matlab}:
918     \begin{verbatim}
919     % matlab
920     >> H=rdmds('Depth');
921     >> contourf(H');colorbar;
922     >> title('Depth of fluid as used by model');
923    
924     >> eta=rdmds('Eta',10);
925     >> imagesc(eta');axis ij;colorbar;
926     >> title('Surface height at iter=10');
927    
928     >> eta=rdmds('Eta',[0:10:100]);
929     >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end
930     \end{verbatim}
931 adcroft 1.1
932 edhill 1.31 Similar scripts for netCDF output (\texttt{rdmnc.m}) are available and
933     they are described in Section \ref{sec:pkg:mnc}.
934    
935 molod 1.38 The MNC output files are all in the ``self-describing'' netCDF
936     format and can thus be browsed and/or plotted using tools such as:
937     \begin{itemize}
938     \item \texttt{ncdump} is a utility which is typically included
939     with every netCDF install:
940     \begin{rawhtml} <A href="http://www.unidata.ucar.edu/packages/netcdf/"> \end{rawhtml}
941     \begin{verbatim}
942     http://www.unidata.ucar.edu/packages/netcdf/
943     \end{verbatim}
944     \begin{rawhtml} </A> \end{rawhtml} and it converts the netCDF
945     binaries into formatted ASCII text files.
946    
947     \item \texttt{ncview} utility is a very convenient and quick way
948     to plot netCDF data and it runs on most OSes:
949     \begin{rawhtml} <A href="http://meteora.ucsd.edu/~pierce/ncview_home_page.html"> \end{rawhtml}
950     \begin{verbatim}
951     http://meteora.ucsd.edu/~pierce/ncview_home_page.html
952     \end{verbatim}
953     \begin{rawhtml} </A> \end{rawhtml}
954    
955     \item MatLAB(c) and other common post-processing environments provide
956     various netCDF interfaces including:
957     \begin{rawhtml} <A href="http://mexcdf.sourceforge.net/"> \end{rawhtml}
958     \begin{verbatim}
959     http://mexcdf.sourceforge.net/
960     \end{verbatim}
961     \begin{rawhtml} </A> \end{rawhtml}
962     \begin{rawhtml} <A href="http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html"> \end{rawhtml}
963     \begin{verbatim}
964     http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html
965     \end{verbatim}
966     \begin{rawhtml} </A> \end{rawhtml}
967     \end{itemize}
968    

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