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1 cnh 1.28 % $Header: /u/gcmpack/manual/part3/getting_started.tex,v 1.27 2004/10/14 14:24:28 cnh 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    
21 edhill 1.15 A web site is maintained for release 2 (``Pelican'') of MITgcm:
22     \begin{rawhtml} <A href=http://mitgcm.org/pelican/ target="idontexist"> \end{rawhtml}
23 adcroft 1.4 \begin{verbatim}
24 edhill 1.15 http://mitgcm.org/pelican
25 adcroft 1.4 \end{verbatim}
26 edhill 1.15 \begin{rawhtml} </A> \end{rawhtml}
27 adcroft 1.4 Here you will find an on-line version of this document, a
28     ``browsable'' copy of the code and a searchable database of the model
29     and site, as well as links for downloading the model and
30 edhill 1.15 documentation, to data-sources, and other related sites.
31 adcroft 1.4
32 edhill 1.15 There is also a web-archived support mailing list for the model that
33     you can email at \texttt{MITgcm-support@mitgcm.org} or browse at:
34     \begin{rawhtml} <A href=http://mitgcm.org/mailman/listinfo/mitgcm-support/ target="idontexist"> \end{rawhtml}
35     \begin{verbatim}
36     http://mitgcm.org/mailman/listinfo/mitgcm-support/
37     http://mitgcm.org/pipermail/mitgcm-support/
38     \end{verbatim}
39     \begin{rawhtml} </A> \end{rawhtml}
40     Essentially all of the MITgcm web pages can be searched using a
41     popular web crawler such as Google or through our own search facility:
42 edhill 1.16 \begin{rawhtml} <A href=http://mitgcm.org/mailman/htdig/ target="idontexist"> \end{rawhtml}
43 adcroft 1.1 \begin{verbatim}
44 edhill 1.15 http://mitgcm.org/htdig/
45 adcroft 1.1 \end{verbatim}
46 edhill 1.15 \begin{rawhtml} </A> \end{rawhtml}
47     %%% http://www.google.com/search?q=hydrostatic+site%3Amitgcm.org
48    
49    
50 adcroft 1.4
51     \section{Obtaining the code}
52     \label{sect:obtainingCode}
53 adcroft 1.1
54 cnh 1.7 MITgcm can be downloaded from our system by following
55     the instructions below. As a courtesy we ask that you send e-mail to us at
56 edhill 1.14 \begin{rawhtml} <A href=mailto:MITgcm-support@mitgcm.org> \end{rawhtml}
57     MITgcm-support@mitgcm.org
58 cnh 1.7 \begin{rawhtml} </A> \end{rawhtml}
59     to enable us to keep track of who's using the model and in what application.
60     You can download the model two ways:
61    
62     \begin{enumerate}
63 cnh 1.9 \item Using CVS software. CVS is a freely available source code management
64 cnh 1.7 tool. To use CVS you need to have the software installed. Many systems
65     come with CVS pre-installed, otherwise good places to look for
66     the software for a particular platform are
67     \begin{rawhtml} <A href=http://www.cvshome.org/ target="idontexist"> \end{rawhtml}
68     cvshome.org
69     \begin{rawhtml} </A> \end{rawhtml}
70     and
71     \begin{rawhtml} <A href=http://www.wincvs.org/ target="idontexist"> \end{rawhtml}
72     wincvs.org
73     \begin{rawhtml} </A> \end{rawhtml}
74     .
75    
76     \item Using a tar file. This method is simple and does not
77     require any special software. However, this method does not
78     provide easy support for maintenance updates.
79    
80     \end{enumerate}
81    
82 cnh 1.27 \subsection{Method 1 - Checkout from CVS}
83 edhill 1.19 \label{sect:cvs_checkout}
84    
85 adcroft 1.1 If CVS is available on your system, we strongly encourage you to use it. CVS
86     provides an efficient and elegant way of organizing your code and keeping
87     track of your changes. If CVS is not available on your machine, you can also
88     download a tar file.
89    
90 edhill 1.15 Before you can use CVS, the following environment variable(s) should
91     be set within your shell. For a csh or tcsh shell, put the following
92     \begin{verbatim}
93     % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/gcmpack
94     \end{verbatim}
95     in your .cshrc or .tcshrc file. For bash or sh shells, put:
96 adcroft 1.1 \begin{verbatim}
97 edhill 1.15 % export CVSROOT=':pserver:cvsanon@mitgcm.org:/u/gcmpack'
98 adcroft 1.6 \end{verbatim}
99 edhill 1.20 in your \texttt{.profile} or \texttt{.bashrc} file.
100 adcroft 1.6
101 edhill 1.15
102     To get MITgcm through CVS, first register with the MITgcm CVS server
103     using command:
104 adcroft 1.6 \begin{verbatim}
105 adcroft 1.1 % cvs login ( CVS password: cvsanon )
106     \end{verbatim}
107 edhill 1.15 You only need to do a ``cvs login'' once.
108 adcroft 1.1
109 edhill 1.15 To obtain the latest sources type:
110     \begin{verbatim}
111     % cvs co MITgcm
112     \end{verbatim}
113     or to get a specific release type:
114 adcroft 1.1 \begin{verbatim}
115 edhill 1.16 % cvs co -P -r checkpoint52i_post MITgcm
116 adcroft 1.1 \end{verbatim}
117 edhill 1.15 The MITgcm web site contains further directions concerning the source
118     code and CVS. It also contains a web interface to our CVS archive so
119     that one may easily view the state of files, revisions, and other
120     development milestones:
121 edhill 1.17 \begin{rawhtml} <A href=''http://mitgcm.org/download'' target="idontexist"> \end{rawhtml}
122 edhill 1.15 \begin{verbatim}
123 edhill 1.17 http://mitgcm.org/source_code.html
124 edhill 1.15 \end{verbatim}
125     \begin{rawhtml} </A> \end{rawhtml}
126 adcroft 1.1
127 edhill 1.19 As a convenience, the MITgcm CVS server contains aliases which are
128     named subsets of the codebase. These aliases can be especially
129     helpful when used over slow internet connections or on machines with
130     restricted storage space. Table \ref{tab:cvsModules} contains a list
131     of CVS aliases
132     \begin{table}[htb]
133     \centering
134     \begin{tabular}[htb]{|lp{3.25in}|}\hline
135     \textbf{Alias Name} & \textbf{Information (directories) Contained} \\\hline
136     \texttt{MITgcm\_code} & Only the source code -- none of the verification examples. \\
137     \texttt{MITgcm\_verif\_basic}
138     & Source code plus a small set of the verification examples
139     (\texttt{global\_ocean.90x40x15}, \texttt{aim.5l\_cs}, \texttt{hs94.128x64x5},
140     \texttt{front\_relax}, and \texttt{plume\_on\_slope}). \\
141     \texttt{MITgcm\_verif\_atmos} & Source code plus all of the atmospheric examples. \\
142     \texttt{MITgcm\_verif\_ocean} & Source code plus all of the oceanic examples. \\
143     \texttt{MITgcm\_verif\_all} & Source code plus all of the
144     verification examples. \\\hline
145     \end{tabular}
146     \caption{MITgcm CVS Modules}
147     \label{tab:cvsModules}
148     \end{table}
149 edhill 1.15
150     The checkout process creates a directory called \textit{MITgcm}. If
151     the directory \textit{MITgcm} exists this command updates your code
152     based on the repository. Each directory in the source tree contains a
153     directory \textit{CVS}. This information is required by CVS to keep
154     track of your file versions with respect to the repository. Don't edit
155     the files in \textit{CVS}! You can also use CVS to download code
156     updates. More extensive information on using CVS for maintaining
157     MITgcm code can be found
158 edhill 1.17 \begin{rawhtml} <A href=''http://mitgcm.org/usingcvstoget.html'' target="idontexist"> \end{rawhtml}
159 cnh 1.7 here
160     \begin{rawhtml} </A> \end{rawhtml}
161     .
162 edhill 1.19 It is important to note that the CVS aliases in Table
163     \ref{tab:cvsModules} cannot be used in conjunction with the CVS
164     \texttt{-d DIRNAME} option. However, the \texttt{MITgcm} directories
165     they create can be changed to a different name following the check-out:
166     \begin{verbatim}
167     % cvs co MITgcm_verif_basic
168     % mv MITgcm MITgcm_verif_basic
169     \end{verbatim}
170 cnh 1.7
171 adcroft 1.1
172 cnh 1.27 \subsection{Method 2 - Tar file download}
173 adcroft 1.4 \label{sect:conventionalDownload}
174 adcroft 1.1
175 adcroft 1.4 If you do not have CVS on your system, you can download the model as a
176 edhill 1.15 tar file from the web site at:
177 cnh 1.7 \begin{rawhtml} <A href=http://mitgcm.org/download target="idontexist"> \end{rawhtml}
178 adcroft 1.1 \begin{verbatim}
179     http://mitgcm.org/download/
180     \end{verbatim}
181 cnh 1.7 \begin{rawhtml} </A> \end{rawhtml}
182 adcroft 1.4 The tar file still contains CVS information which we urge you not to
183     delete; even if you do not use CVS yourself the information can help
184 edhill 1.15 us if you should need to send us your copy of the code. If a recent
185     tar file does not exist, then please contact the developers through
186 edhill 1.17 the
187     \begin{rawhtml} <A href=''mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
188     MITgcm-support@mitgcm.org
189     \begin{rawhtml} </A> \end{rawhtml}
190     mailing list.
191 adcroft 1.1
192 edhill 1.19 \subsubsection{Upgrading from an earlier version}
193 adcroft 1.12
194     If you already have an earlier version of the code you can ``upgrade''
195     your copy instead of downloading the entire repository again. First,
196     ``cd'' (change directory) to the top of your working copy:
197     \begin{verbatim}
198     % cd MITgcm
199     \end{verbatim}
200 edhill 1.15 and then issue the cvs update command such as:
201 adcroft 1.12 \begin{verbatim}
202 edhill 1.16 % cvs -q update -r checkpoint52i_post -d -P
203 adcroft 1.12 \end{verbatim}
204 edhill 1.16 This will update the ``tag'' to ``checkpoint52i\_post'', add any new
205 adcroft 1.12 directories (-d) and remove any empty directories (-P). The -q option
206     means be quiet which will reduce the number of messages you'll see in
207     the terminal. If you have modified the code prior to upgrading, CVS
208     will try to merge your changes with the upgrades. If there is a
209     conflict between your modifications and the upgrade, it will report
210     that file with a ``C'' in front, e.g.:
211     \begin{verbatim}
212     C model/src/ini_parms.F
213     \end{verbatim}
214     If the list of conflicts scrolled off the screen, you can re-issue the
215     cvs update command and it will report the conflicts. Conflicts are
216 edhill 1.15 indicated in the code by the delimites ``$<<<<<<<$'', ``======='' and
217     ``$>>>>>>>$''. For example,
218 edhill 1.17 {\small
219 adcroft 1.12 \begin{verbatim}
220     <<<<<<< ini_parms.F
221     & bottomDragLinear,myOwnBottomDragCoefficient,
222     =======
223     & bottomDragLinear,bottomDragQuadratic,
224     >>>>>>> 1.18
225     \end{verbatim}
226 edhill 1.17 }
227 adcroft 1.12 means that you added ``myOwnBottomDragCoefficient'' to a namelist at
228     the same time and place that we added ``bottomDragQuadratic''. You
229     need to resolve this conflict and in this case the line should be
230     changed to:
231 edhill 1.17 {\small
232 adcroft 1.12 \begin{verbatim}
233     & bottomDragLinear,bottomDragQuadratic,myOwnBottomDragCoefficient,
234     \end{verbatim}
235 edhill 1.17 }
236 edhill 1.15 and the lines with the delimiters ($<<<<<<$,======,$>>>>>>$) be deleted.
237 adcroft 1.12 Unless you are making modifications which exactly parallel
238     developments we make, these types of conflicts should be rare.
239    
240     \paragraph*{Upgrading to the current pre-release version}
241    
242     We don't make a ``release'' for every little patch and bug fix in
243     order to keep the frequency of upgrades to a minimum. However, if you
244     have run into a problem for which ``we have already fixed in the
245     latest code'' and we haven't made a ``tag'' or ``release'' since that
246     patch then you'll need to get the latest code:
247     \begin{verbatim}
248     % cvs -q update -A -d -P
249     \end{verbatim}
250     Unlike, the ``check-out'' and ``update'' procedures above, there is no
251     ``tag'' or release name. The -A tells CVS to upgrade to the
252     very latest version. As a rule, we don't recommend this since you
253     might upgrade while we are in the processes of checking in the code so
254     that you may only have part of a patch. Using this method of updating
255     also means we can't tell what version of the code you are working
256     with. So please be sure you understand what you're doing.
257    
258 adcroft 1.4 \section{Model and directory structure}
259 adcroft 1.1
260 adcroft 1.12 The ``numerical'' model is contained within a execution environment
261     support wrapper. This wrapper is designed to provide a general
262     framework for grid-point models. MITgcmUV is a specific numerical
263     model that uses the framework. Under this structure the model is split
264     into execution environment support code and conventional numerical
265     model code. The execution environment support code is held under the
266     \textit{eesupp} directory. The grid point model code is held under the
267     \textit{model} directory. Code execution actually starts in the
268     \textit{eesupp} routines and not in the \textit{model} routines. For
269 edhill 1.17 this reason the top-level \textit{MAIN.F} is in the
270     \textit{eesupp/src} directory. In general, end-users should not need
271     to worry about this level. The top-level routine for the numerical
272     part of the code is in \textit{model/src/THE\_MODEL\_MAIN.F}. Here is
273     a brief description of the directory structure of the model under the
274     root tree (a detailed description is given in section 3: Code
275     structure).
276 adcroft 1.1
277     \begin{itemize}
278    
279 edhill 1.17 \item \textit{bin}: this directory is initially empty. It is the
280     default directory in which to compile the code.
281    
282 adcroft 1.1 \item \textit{diags}: contains the code relative to time-averaged
283 edhill 1.17 diagnostics. It is subdivided into two subdirectories \textit{inc}
284     and \textit{src} that contain include files (*.\textit{h} files) and
285     Fortran subroutines (*.\textit{F} files), respectively.
286 adcroft 1.1
287     \item \textit{doc}: contains brief documentation notes.
288 edhill 1.17
289     \item \textit{eesupp}: contains the execution environment source code.
290     Also subdivided into two subdirectories \textit{inc} and
291     \textit{src}.
292    
293     \item \textit{exe}: this directory is initially empty. It is the
294     default directory in which to execute the code.
295    
296     \item \textit{model}: this directory contains the main source code.
297     Also subdivided into two subdirectories \textit{inc} and
298     \textit{src}.
299    
300     \item \textit{pkg}: contains the source code for the packages. Each
301     package corresponds to a subdirectory. For example, \textit{gmredi}
302     contains the code related to the Gent-McWilliams/Redi scheme,
303     \textit{aim} the code relative to the atmospheric intermediate
304     physics. The packages are described in detail in section 3.
305    
306     \item \textit{tools}: this directory contains various useful tools.
307     For example, \textit{genmake2} is a script written in csh (C-shell)
308     that should be used to generate your makefile. The directory
309     \textit{adjoint} contains the makefile specific to the Tangent
310     linear and Adjoint Compiler (TAMC) that generates the adjoint code.
311     The latter is described in details in part V.
312    
313 adcroft 1.1 \item \textit{utils}: this directory contains various utilities. The
314 edhill 1.17 subdirectory \textit{knudsen2} contains code and a makefile that
315     compute coefficients of the polynomial approximation to the knudsen
316     formula for an ocean nonlinear equation of state. The
317     \textit{matlab} subdirectory contains matlab scripts for reading
318     model output directly into matlab. \textit{scripts} contains C-shell
319     post-processing scripts for joining processor-based and tiled-based
320     model output.
321    
322     \item \textit{verification}: this directory contains the model
323     examples. See section \ref{sect:modelExamples}.
324 adcroft 1.1
325     \end{itemize}
326    
327 cnh 1.26 \section[MITgcm Example Experiments]{Example experiments}
328 adcroft 1.4 \label{sect:modelExamples}
329 adcroft 1.1
330 edhill 1.15 %% a set of twenty-four pre-configured numerical experiments
331    
332     The MITgcm distribution comes with more than a dozen pre-configured
333     numerical experiments. Some of these example experiments are tests of
334     individual parts of the model code, but many are fully fledged
335     numerical simulations. A few of the examples are used for tutorial
336     documentation in sections \ref{sect:eg-baro} - \ref{sect:eg-global}.
337     The other examples follow the same general structure as the tutorial
338     examples. However, they only include brief instructions in a text file
339     called {\it README}. The examples are located in subdirectories under
340     the directory \textit{verification}. Each example is briefly described
341     below.
342 adcroft 1.1
343 cnh 1.8 \subsection{Full list of model examples}
344 adcroft 1.1
345 cnh 1.8 \begin{enumerate}
346 edhill 1.17
347 adcroft 1.1 \item \textit{exp0} - single layer, ocean double gyre (barotropic with
348 edhill 1.15 free-surface). This experiment is described in detail in section
349     \ref{sect:eg-baro}.
350 adcroft 1.1
351 edhill 1.15 \item \textit{exp1} - Four layer, ocean double gyre. This experiment
352     is described in detail in section \ref{sect:eg-baroc}.
353    
354 adcroft 1.1 \item \textit{exp2} - 4x4 degree global ocean simulation with steady
355 edhill 1.15 climatological forcing. This experiment is described in detail in
356     section \ref{sect:eg-global}.
357    
358     \item \textit{exp4} - Flow over a Gaussian bump in open-water or
359     channel with open boundaries.
360    
361     \item \textit{exp5} - Inhomogenously forced ocean convection in a
362     doubly periodic box.
363 adcroft 1.1
364 cnh 1.8 \item \textit{front\_relax} - Relaxation of an ocean thermal front (test for
365 adcroft 1.1 Gent/McWilliams scheme). 2D (Y-Z).
366    
367 edhill 1.15 \item \textit{internal wave} - Ocean internal wave forced by open
368     boundary conditions.
369    
370 cnh 1.8 \item \textit{natl\_box} - Eastern subtropical North Atlantic with KPP
371 edhill 1.15 scheme; 1 month integration
372    
373     \item \textit{hs94.1x64x5} - Zonal averaged atmosphere using Held and
374     Suarez '94 forcing.
375    
376     \item \textit{hs94.128x64x5} - 3D atmosphere dynamics using Held and
377     Suarez '94 forcing.
378    
379 adcroft 1.1 \item \textit{hs94.cs-32x32x5} - 3D atmosphere dynamics using Held and
380 edhill 1.15 Suarez '94 forcing on the cubed sphere.
381    
382     \item \textit{aim.5l\_zon-ave} - Intermediate Atmospheric physics.
383     Global Zonal Mean configuration, 1x64x5 resolution.
384    
385     \item \textit{aim.5l\_XZ\_Equatorial\_Slice} - Intermediate
386     Atmospheric physics, equatorial Slice configuration. 2D (X-Z).
387    
388 adcroft 1.1 \item \textit{aim.5l\_Equatorial\_Channel} - Intermediate Atmospheric
389 edhill 1.15 physics. 3D Equatorial Channel configuration.
390    
391 cnh 1.8 \item \textit{aim.5l\_LatLon} - Intermediate Atmospheric physics.
392 edhill 1.15 Global configuration, on latitude longitude grid with 128x64x5 grid
393     points ($2.8^\circ{\rm degree}$ resolution).
394    
395     \item \textit{adjustment.128x64x1} Barotropic adjustment problem on
396     latitude longitude grid with 128x64 grid points ($2.8^\circ{\rm
397     degree}$ resolution).
398    
399     \item \textit{adjustment.cs-32x32x1} Barotropic adjustment problem on
400     cube sphere grid with 32x32 points per face ( roughly $2.8^\circ{\rm
401     degree}$ resolution).
402    
403 cnh 1.8 \item \textit{advect\_cs} Two-dimensional passive advection test on
404 edhill 1.15 cube sphere grid.
405    
406     \item \textit{advect\_xy} Two-dimensional (horizontal plane) passive
407     advection test on Cartesian grid.
408    
409     \item \textit{advect\_yz} Two-dimensional (vertical plane) passive
410     advection test on Cartesian grid.
411    
412     \item \textit{carbon} Simple passive tracer experiment. Includes
413     derivative calculation. Described in detail in section
414     \ref{sect:eg-carbon-ad}.
415 cnh 1.8
416     \item \textit{flt\_example} Example of using float package.
417 edhill 1.15
418     \item \textit{global\_ocean.90x40x15} Global circulation with GM, flux
419     boundary conditions and poles.
420 cnh 1.8
421 mlosch 1.13 \item \textit{global\_ocean\_pressure} Global circulation in pressure
422     coordinate (non-Boussinesq ocean model). Described in detail in
423     section \ref{sect:eg-globalpressure}.
424 edhill 1.15
425     \item \textit{solid-body.cs-32x32x1} Solid body rotation test for cube
426     sphere grid.
427 cnh 1.8
428     \end{enumerate}
429 adcroft 1.1
430 adcroft 1.4 \subsection{Directory structure of model examples}
431 adcroft 1.1
432     Each example directory has the following subdirectories:
433    
434     \begin{itemize}
435     \item \textit{code}: contains the code particular to the example. At a
436 edhill 1.16 minimum, this directory includes the following files:
437 adcroft 1.1
438 edhill 1.16 \begin{itemize}
439     \item \textit{code/CPP\_EEOPTIONS.h}: declares CPP keys relative to
440     the ``execution environment'' part of the code. The default
441     version is located in \textit{eesupp/inc}.
442    
443     \item \textit{code/CPP\_OPTIONS.h}: declares CPP keys relative to
444     the ``numerical model'' part of the code. The default version is
445     located in \textit{model/inc}.
446    
447     \item \textit{code/SIZE.h}: declares size of underlying
448     computational grid. The default version is located in
449     \textit{model/inc}.
450     \end{itemize}
451    
452     In addition, other include files and subroutines might be present in
453     \textit{code} depending on the particular experiment. See Section 2
454     for more details.
455 edhill 1.15
456     \item \textit{input}: contains the input data files required to run
457     the example. At a minimum, the \textit{input} directory contains the
458     following files:
459 adcroft 1.1
460 edhill 1.16 \begin{itemize}
461     \item \textit{input/data}: this file, written as a namelist,
462     specifies the main parameters for the experiment.
463    
464     \item \textit{input/data.pkg}: contains parameters relative to the
465     packages used in the experiment.
466    
467     \item \textit{input/eedata}: this file contains ``execution
468     environment'' data. At present, this consists of a specification
469     of the number of threads to use in $X$ and $Y$ under multithreaded
470     execution.
471     \end{itemize}
472 edhill 1.17
473     In addition, you will also find in this directory the forcing and
474     topography files as well as the files describing the initial state
475     of the experiment. This varies from experiment to experiment. See
476     section 2 for more details.
477 edhill 1.16
478     \item \textit{results}: this directory contains the output file
479     \textit{output.txt} produced by the simulation example. This file is
480     useful for comparison with your own output when you run the
481     experiment.
482 adcroft 1.1 \end{itemize}
483    
484 edhill 1.17 Once you have chosen the example you want to run, you are ready to
485     compile the code.
486 adcroft 1.1
487 cnh 1.26 \section[Building MITgcm]{Building the code}
488 adcroft 1.4 \label{sect:buildingCode}
489    
490     To compile the code, we use the {\em make} program. This uses a file
491     ({\em Makefile}) that allows us to pre-process source files, specify
492     compiler and optimization options and also figures out any file
493 edhill 1.16 dependencies. We supply a script ({\em genmake2}), described in
494     section \ref{sect:genmake}, that automatically creates the {\em
495     Makefile} for you. You then need to build the dependencies and
496     compile the code.
497 adcroft 1.4
498     As an example, let's assume that you want to build and run experiment
499 edhill 1.16 \textit{verification/exp2}. The are multiple ways and places to
500     actually do this but here let's build the code in
501 adcroft 1.4 \textit{verification/exp2/input}:
502     \begin{verbatim}
503     % cd verification/exp2/input
504     \end{verbatim}
505     First, build the {\em Makefile}:
506     \begin{verbatim}
507 edhill 1.16 % ../../../tools/genmake2 -mods=../code
508 adcroft 1.4 \end{verbatim}
509     The command line option tells {\em genmake} to override model source
510     code with any files in the directory {\em ./code/}.
511    
512 edhill 1.16 On many systems, the {\em genmake2} program will be able to
513     automatically recognize the hardware, find compilers and other tools
514     within the user's path (``echo \$PATH''), and then choose an
515     appropriate set of options from the files contained in the {\em
516     tools/build\_options} directory. Under some circumstances, a user
517     may have to create a new ``optfile'' in order to specify the exact
518     combination of compiler, compiler flags, libraries, and other options
519     necessary to build a particular configuration of MITgcm. In such
520     cases, it is generally helpful to read the existing ``optfiles'' and
521     mimic their syntax.
522    
523     Through the MITgcm-support list, the MITgcm developers are willing to
524     provide help writing or modifing ``optfiles''. And we encourage users
525     to post new ``optfiles'' (particularly ones for new machines or
526 edhill 1.17 architectures) to the
527     \begin{rawhtml} <A href=''mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
528     MITgcm-support@mitgcm.org
529     \begin{rawhtml} </A> \end{rawhtml}
530     list.
531 edhill 1.16
532     To specify an optfile to {\em genmake2}, the syntax is:
533 adcroft 1.4 \begin{verbatim}
534 edhill 1.16 % ../../../tools/genmake2 -mods=../code -of /path/to/optfile
535 adcroft 1.4 \end{verbatim}
536    
537 edhill 1.16 Once a {\em Makefile} has been generated, we create the dependencies:
538 adcroft 1.4 \begin{verbatim}
539     % make depend
540     \end{verbatim}
541 edhill 1.16 This modifies the {\em Makefile} by attaching a [long] list of files
542     upon which other files depend. The purpose of this is to reduce
543     re-compilation if and when you start to modify the code. The {\tt make
544     depend} command also creates links from the model source to this
545     directory.
546 adcroft 1.1
547 edhill 1.16 Next compile the code:
548 adcroft 1.4 \begin{verbatim}
549     % make
550     \end{verbatim}
551     The {\tt make} command creates an executable called \textit{mitgcmuv}.
552 edhill 1.16 Additional make ``targets'' are defined within the makefile to aid in
553     the production of adjoint and other versions of MITgcm.
554 adcroft 1.4
555     Now you are ready to run the model. General instructions for doing so are
556     given in section \ref{sect:runModel}. Here, we can run the model with:
557     \begin{verbatim}
558     ./mitgcmuv > output.txt
559     \end{verbatim}
560     where we are re-directing the stream of text output to the file {\em
561     output.txt}.
562    
563    
564 cnh 1.26 \section[Running MITgcm]{Running the model in prognostic mode}
565 adcroft 1.4 \label{sect:runModel}
566    
567 edhill 1.23 If compilation finished succesfuully (section \ref{sect:buildingCode})
568     then an executable called \texttt{mitgcmuv} will now exist in the
569     local directory.
570 adcroft 1.1
571 adcroft 1.4 To run the model as a single process (ie. not in parallel) simply
572     type:
573 adcroft 1.1 \begin{verbatim}
574 adcroft 1.4 % ./mitgcmuv
575 adcroft 1.1 \end{verbatim}
576 adcroft 1.4 The ``./'' is a safe-guard to make sure you use the local executable
577     in case you have others that exist in your path (surely odd if you
578     do!). The above command will spew out many lines of text output to
579     your screen. This output contains details such as parameter values as
580     well as diagnostics such as mean Kinetic energy, largest CFL number,
581     etc. It is worth keeping this text output with the binary output so we
582     normally re-direct the {\em stdout} stream as follows:
583 adcroft 1.1 \begin{verbatim}
584 adcroft 1.4 % ./mitgcmuv > output.txt
585 adcroft 1.1 \end{verbatim}
586    
587 edhill 1.17 For the example experiments in {\em verification}, an example of the
588 adcroft 1.4 output is kept in {\em results/output.txt} for comparison. You can compare
589     your {\em output.txt} with this one to check that the set-up works.
590 adcroft 1.1
591    
592    
593 adcroft 1.4 \subsection{Output files}
594 adcroft 1.1
595     The model produces various output files. At a minimum, the instantaneous
596     ``state'' of the model is written out, which is made of the following files:
597    
598     \begin{itemize}
599     \item \textit{U.00000nIter} - zonal component of velocity field (m/s and $>
600     0 $ eastward).
601    
602     \item \textit{V.00000nIter} - meridional component of velocity field (m/s
603     and $> 0$ northward).
604    
605     \item \textit{W.00000nIter} - vertical component of velocity field (ocean:
606     m/s and $> 0$ upward, atmosphere: Pa/s and $> 0$ towards increasing pressure
607     i.e. downward).
608    
609     \item \textit{T.00000nIter} - potential temperature (ocean: $^{0}$C,
610     atmosphere: $^{0}$K).
611    
612     \item \textit{S.00000nIter} - ocean: salinity (psu), atmosphere: water vapor
613     (g/kg).
614    
615     \item \textit{Eta.00000nIter} - ocean: surface elevation (m), atmosphere:
616     surface pressure anomaly (Pa).
617     \end{itemize}
618    
619     The chain \textit{00000nIter} consists of ten figures that specify the
620     iteration number at which the output is written out. For example, \textit{%
621     U.0000000300} is the zonal velocity at iteration 300.
622    
623     In addition, a ``pickup'' or ``checkpoint'' file called:
624    
625     \begin{itemize}
626     \item \textit{pickup.00000nIter}
627     \end{itemize}
628    
629     is written out. This file represents the state of the model in a condensed
630     form and is used for restarting the integration. If the C-D scheme is used,
631     there is an additional ``pickup'' file:
632    
633     \begin{itemize}
634     \item \textit{pickup\_cd.00000nIter}
635     \end{itemize}
636    
637     containing the D-grid velocity data and that has to be written out as well
638     in order to restart the integration. Rolling checkpoint files are the same
639     as the pickup files but are named differently. Their name contain the chain
640     \textit{ckptA} or \textit{ckptB} instead of \textit{00000nIter}. They can be
641     used to restart the model but are overwritten every other time they are
642     output to save disk space during long integrations.
643    
644 adcroft 1.4 \subsection{Looking at the output}
645 adcroft 1.1
646     All the model data are written according to a ``meta/data'' file format.
647     Each variable is associated with two files with suffix names \textit{.data}
648     and \textit{.meta}. The \textit{.data} file contains the data written in
649     binary form (big\_endian by default). The \textit{.meta} file is a
650     ``header'' file that contains information about the size and the structure
651     of the \textit{.data} file. This way of organizing the output is
652     particularly useful when running multi-processors calculations. The base
653     version of the model includes a few matlab utilities to read output files
654     written in this format. The matlab scripts are located in the directory
655     \textit{utils/matlab} under the root tree. The script \textit{rdmds.m} reads
656     the data. Look at the comments inside the script to see how to use it.
657    
658 adcroft 1.4 Some examples of reading and visualizing some output in {\em Matlab}:
659     \begin{verbatim}
660     % matlab
661     >> H=rdmds('Depth');
662     >> contourf(H');colorbar;
663     >> title('Depth of fluid as used by model');
664    
665     >> eta=rdmds('Eta',10);
666     >> imagesc(eta');axis ij;colorbar;
667     >> title('Surface height at iter=10');
668    
669     >> eta=rdmds('Eta',[0:10:100]);
670     >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end
671     \end{verbatim}
672 adcroft 1.1

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