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revision 1.28 by cnh, Thu Oct 14 14:54:24 2004 UTC revision 1.40 by jmc, Thu Jan 21 19:20:08 2010 UTC
# Line 3  Line 3 
3    
4  %\section{Getting started}  %\section{Getting started}
5    
6  In this section, we describe how to use the model. In the first  We believe the best way to familiarize yourself with the
 section, we provide enough information to help you get started with  
 the model. We believe the best way to familiarize yourself with the  
7  model is to run the case study examples provided with the base  model is to run the case study examples provided with the base
8  version. Information on how to obtain, compile, and run the code is  version. Information on how to obtain, compile, and run the code is
9  found there as well as a brief description of the model structure  found here as well as a brief description of the model structure
10  directory and the case study examples.  The latter and the code  directory and the case study examples. Information is also provided
11  structure are described more fully in chapters  here on how to customize the code when you are ready to try implementing
12  \ref{chap:discretization} and \ref{chap:sarch}, respectively. Here, in  the configuration you have in mind.  The code and algorithm
13  this section, we provide information on how to customize the code when  are described more fully in chapters \ref{chap:discretization} and
14  you are ready to try implementing the configuration you have in mind.  \ref{chap:sarch}.
15    
16  \section{Where to find information}  \section{Where to find information}
17  \label{sect:whereToFindInfo}  \label{sect:whereToFindInfo}
18    \begin{rawhtml}
19    <!-- CMIREDIR:whereToFindInfo: -->
20    \end{rawhtml}
21    
22  A web site is maintained for release 2 (``Pelican'') of MITgcm:  There is a web-archived support mailing list for the model that
 \begin{rawhtml} <A href=http://mitgcm.org/pelican/ target="idontexist"> \end{rawhtml}  
 \begin{verbatim}  
 http://mitgcm.org/pelican  
 \end{verbatim}  
 \begin{rawhtml} </A> \end{rawhtml}  
 Here you will find an on-line version of this document, a  
 ``browsable'' copy of the code and a searchable database of the model  
 and site, as well as links for downloading the model and  
 documentation, to data-sources, and other related sites.  
   
 There is also a web-archived support mailing list for the model that  
23  you can email at \texttt{MITgcm-support@mitgcm.org} or browse at:  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}  \begin{rawhtml} <A href=http://mitgcm.org/mailman/listinfo/mitgcm-support/ target="idontexist"> \end{rawhtml}
25  \begin{verbatim}  \begin{verbatim}
# Line 37  http://mitgcm.org/mailman/listinfo/mitgc Line 27  http://mitgcm.org/mailman/listinfo/mitgc
27  http://mitgcm.org/pipermail/mitgcm-support/  http://mitgcm.org/pipermail/mitgcm-support/
28  \end{verbatim}  \end{verbatim}
29  \begin{rawhtml} </A> \end{rawhtml}  \begin{rawhtml} </A> \end{rawhtml}
 Essentially all of the MITgcm web pages can be searched using a  
 popular web crawler such as Google or through our own search facility:  
 \begin{rawhtml} <A href=http://mitgcm.org/mailman/htdig/ target="idontexist"> \end{rawhtml}  
 \begin{verbatim}  
 http://mitgcm.org/htdig/  
 \end{verbatim}  
 \begin{rawhtml} </A> \end{rawhtml}  
 %%% http://www.google.com/search?q=hydrostatic+site%3Amitgcm.org  
   
   
30    
31  \section{Obtaining the code}  \section{Obtaining the code}
32  \label{sect:obtainingCode}  \label{sect:obtainingCode}
33    \begin{rawhtml}
34    <!-- CMIREDIR:obtainingCode: -->
35    \end{rawhtml}
36    
37  MITgcm can be downloaded from our system by following  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  the instructions below. As a courtesy we ask that you send e-mail to us at
# Line 92  be set within your shell.  For a csh or Line 75  be set within your shell.  For a csh or
75  \begin{verbatim}  \begin{verbatim}
76  % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/gcmpack  % setenv CVSROOT :pserver:cvsanon@mitgcm.org:/u/gcmpack
77  \end{verbatim}  \end{verbatim}
78  in your .cshrc or .tcshrc file.  For bash or sh shells, put:  in your \texttt{.cshrc} or \texttt{.tcshrc} file.  For bash or sh
79    shells, put:
80  \begin{verbatim}  \begin{verbatim}
81  % export CVSROOT=':pserver:cvsanon@mitgcm.org:/u/gcmpack'  % export CVSROOT=':pserver:cvsanon@mitgcm.org:/u/gcmpack'
82  \end{verbatim}  \end{verbatim}
# Line 118  The MITgcm web site contains further dir Line 102  The MITgcm web site contains further dir
102  code and CVS.  It also contains a web interface to our CVS archive so  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  that one may easily view the state of files, revisions, and other
104  development milestones:  development milestones:
105  \begin{rawhtml} <A href=''http://mitgcm.org/download'' target="idontexist"> \end{rawhtml}  %\begin{rawhtml} <A href="http://mitgcm.org/download" target="idontexist"> \end{rawhtml}
106    \begin{rawhtml} <A href="http://mitgcm.org/viewvc/MITgcm/MITgcm/" target="idontexist"> \end{rawhtml}
107  \begin{verbatim}  \begin{verbatim}
108  http://mitgcm.org/source_code.html  http://mitgcm.org/source_code.html
109  \end{verbatim}  \end{verbatim}
# Line 147  of CVS aliases Line 132  of CVS aliases
132    \label{tab:cvsModules}    \label{tab:cvsModules}
133  \end{table}  \end{table}
134    
135  The checkout process creates a directory called \textit{MITgcm}. If  The checkout process creates a directory called \texttt{MITgcm}. If
136  the directory \textit{MITgcm} exists this command updates your code  the directory \texttt{MITgcm} exists this command updates your code
137  based on the repository. Each directory in the source tree contains a  based on the repository. Each directory in the source tree contains a
138  directory \textit{CVS}. This information is required by CVS to keep  directory \texttt{CVS}. This information is required by CVS to keep
139  track of your file versions with respect to the repository. Don't edit  track of your file versions with respect to the repository. Don't edit
140  the files in \textit{CVS}!  You can also use CVS to download code  the files in \texttt{CVS}!  You can also use CVS to download code
141  updates.  More extensive information on using CVS for maintaining  updates.  More extensive information on using CVS for maintaining
142  MITgcm code can be found  MITgcm code can be found
143  \begin{rawhtml} <A href=''http://mitgcm.org/usingcvstoget.html'' target="idontexist"> \end{rawhtml}  \begin{rawhtml} <A href="http://mitgcm.org/usingcvstoget.html" target="idontexist"> \end{rawhtml}
144  here  here
145  \begin{rawhtml} </A> \end{rawhtml}  \begin{rawhtml} </A> \end{rawhtml}
146  .  .
# Line 168  they create can be changed to a differen Line 153  they create can be changed to a differen
153     %  mv MITgcm MITgcm_verif_basic     %  mv MITgcm MITgcm_verif_basic
154  \end{verbatim}  \end{verbatim}
155    
   
 \subsection{Method 2 - Tar file download}  
 \label{sect:conventionalDownload}  
   
 If you do not have CVS on your system, you can download the model as a  
 tar file from the web site at:  
 \begin{rawhtml} <A href=http://mitgcm.org/download target="idontexist"> \end{rawhtml}  
 \begin{verbatim}  
 http://mitgcm.org/download/  
 \end{verbatim}  
 \begin{rawhtml} </A> \end{rawhtml}  
 The tar file still contains CVS information which we urge you not to  
 delete; even if you do not use CVS yourself the information can help  
 us if you should need to send us your copy of the code.  If a recent  
 tar file does not exist, then please contact the developers through  
 the  
 \begin{rawhtml} <A href=''mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}  
 MITgcm-support@mitgcm.org  
 \begin{rawhtml} </A> \end{rawhtml}  
 mailing list.  
   
156  \subsubsection{Upgrading from an earlier version}  \subsubsection{Upgrading from an earlier version}
157    
158  If you already have an earlier version of the code you can ``upgrade''  If you already have an earlier version of the code you can ``upgrade''
# Line 255  that you may only have part of a patch. Line 219  that you may only have part of a patch.
219  also means we can't tell what version of the code you are working  also means we can't tell what version of the code you are working
220  with. So please be sure you understand what you're doing.  with. So please be sure you understand what you're doing.
221    
222    \subsection{Method 2 - Tar file download}
223    \label{sect:conventionalDownload}
224    
225    If you do not have CVS on your system, you can download the model as a
226    tar file from the web site at:
227    \begin{rawhtml} <A href=http://mitgcm.org/download/ target="idontexist"> \end{rawhtml}
228    \begin{verbatim}
229    http://mitgcm.org/download/
230    \end{verbatim}
231    \begin{rawhtml} </A> \end{rawhtml}
232    The tar file still contains CVS information which we urge you not to
233    delete; even if you do not use CVS yourself the information can help
234    us if you should need to send us your copy of the code.  If a recent
235    tar file does not exist, then please contact the developers through
236    the
237    \begin{rawhtml} <A href="mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
238    MITgcm-support@mitgcm.org
239    \begin{rawhtml} </A> \end{rawhtml}
240    mailing list.
241    
242  \section{Model and directory structure}  \section{Model and directory structure}
243    \begin{rawhtml}
244    <!-- CMIREDIR:directory_structure: -->
245    \end{rawhtml}
246    
247  The ``numerical'' model is contained within a execution environment  The ``numerical'' model is contained within a execution environment
248  support wrapper. This wrapper is designed to provide a general  support wrapper. This wrapper is designed to provide a general
# Line 263  framework for grid-point models. MITgcmU Line 250  framework for grid-point models. MITgcmU
250  model that uses the framework. Under this structure the model is split  model that uses the framework. Under this structure the model is split
251  into execution environment support code and conventional numerical  into execution environment support code and conventional numerical
252  model code. The execution environment support code is held under the  model code. The execution environment support code is held under the
253  \textit{eesupp} directory. The grid point model code is held under the  \texttt{eesupp} directory. The grid point model code is held under the
254  \textit{model} directory. Code execution actually starts in the  \texttt{model} directory. Code execution actually starts in the
255  \textit{eesupp} routines and not in the \textit{model} routines. For  \texttt{eesupp} routines and not in the \texttt{model} routines. For
256  this reason the top-level \textit{MAIN.F} is in the  this reason the top-level \texttt{MAIN.F} is in the
257  \textit{eesupp/src} directory. In general, end-users should not need  \texttt{eesupp/src} directory. In general, end-users should not need
258  to worry about this level. The top-level routine for the numerical  to worry about this level. The top-level routine for the numerical
259  part of the code is in \textit{model/src/THE\_MODEL\_MAIN.F}. Here is  part of the code is in \texttt{model/src/THE\_MODEL\_MAIN.F}. Here is
260  a brief description of the directory structure of the model under the  a brief description of the directory structure of the model under the
261  root tree (a detailed description is given in section 3: Code  root tree (a detailed description is given in section 3: Code
262  structure).  structure).
263    
264  \begin{itemize}  \begin{itemize}
265    
266  \item \textit{bin}: this directory is initially empty. It is the  \item \texttt{doc}: contains brief documentation notes.
   default directory in which to compile the code.  
267        
268  \item \textit{diags}: contains the code relative to time-averaged  \item \texttt{eesupp}: contains the execution environment source code.
269    diagnostics. It is subdivided into two subdirectories \textit{inc}    Also subdivided into two subdirectories \texttt{inc} and
270    and \textit{src} that contain include files (*.\textit{h} files) and    \texttt{src}.
271    Fortran subroutines (*.\textit{F} files), respectively.    
272    \item \texttt{model}: this directory contains the main source code.
273  \item \textit{doc}: contains brief documentation notes.    Also subdivided into two subdirectories \texttt{inc} and
274        \texttt{src}.
 \item \textit{eesupp}: contains the execution environment source code.  
   Also subdivided into two subdirectories \textit{inc} and  
   \textit{src}.  
     
 \item \textit{exe}: this directory is initially empty. It is the  
   default directory in which to execute the code.  
275        
276  \item \textit{model}: this directory contains the main source code.  \item \texttt{pkg}: contains the source code for the packages. Each
277    Also subdivided into two subdirectories \textit{inc} and    package corresponds to a subdirectory. For example, \texttt{gmredi}
   \textit{src}.  
     
 \item \textit{pkg}: contains the source code for the packages. Each  
   package corresponds to a subdirectory. For example, \textit{gmredi}  
278    contains the code related to the Gent-McWilliams/Redi scheme,    contains the code related to the Gent-McWilliams/Redi scheme,
279    \textit{aim} the code relative to the atmospheric intermediate    \texttt{aim} the code relative to the atmospheric intermediate
280    physics. The packages are described in detail in section 3.    physics. The packages are described in detail in chapter \ref{chap.packagesI}.
281        
282  \item \textit{tools}: this directory contains various useful tools.  \item \texttt{tools}: this directory contains various useful tools.
283    For example, \textit{genmake2} is a script written in csh (C-shell)    For example, \texttt{genmake2} is a script written in csh (C-shell)
284    that should be used to generate your makefile. The directory    that should be used to generate your makefile. The directory
285    \textit{adjoint} contains the makefile specific to the Tangent    \texttt{adjoint} contains the makefile specific to the Tangent
286    linear and Adjoint Compiler (TAMC) that generates the adjoint code.    linear and Adjoint Compiler (TAMC) that generates the adjoint code.
287    The latter is described in details in part V.    The latter is described in detail in part \ref{chap.ecco}.
288      This directory also contains the subdirectory build\_options, which
289      contains the `optfiles' with the compiler options for the different
290      compilers and machines that can run MITgcm.
291        
292  \item \textit{utils}: this directory contains various utilities. The  \item \texttt{utils}: this directory contains various utilities. The
293    subdirectory \textit{knudsen2} contains code and a makefile that    subdirectory \texttt{knudsen2} contains code and a makefile that
294    compute coefficients of the polynomial approximation to the knudsen    compute coefficients of the polynomial approximation to the knudsen
295    formula for an ocean nonlinear equation of state. The    formula for an ocean nonlinear equation of state. The
296    \textit{matlab} subdirectory contains matlab scripts for reading    \texttt{matlab} subdirectory contains matlab scripts for reading
297    model output directly into matlab. \textit{scripts} contains C-shell    model output directly into matlab. \texttt{scripts} contains C-shell
298    post-processing scripts for joining processor-based and tiled-based    post-processing scripts for joining processor-based and tiled-based
299    model output.    model output. The subdirectory exch2 contains the code needed for
300      the exch2 package to work with different combinations of domain
301      decompositions.
302        
303  \item \textit{verification}: this directory contains the model  \item \texttt{verification}: this directory contains the model
304    examples. See section \ref{sect:modelExamples}.    examples. See section \ref{sect:modelExamples}.
305    
306  \end{itemize}  \item \texttt{jobs}: contains sample job scripts for running MITgcm.
   
 \section[MITgcm Example Experiments]{Example experiments}  
 \label{sect:modelExamples}  
   
 %% a set of twenty-four pre-configured numerical experiments  
   
 The MITgcm distribution comes with more than a dozen pre-configured  
 numerical experiments. Some of these example experiments are tests of  
 individual parts of the model code, but many are fully fledged  
 numerical simulations. A few of the examples are used for tutorial  
 documentation in sections \ref{sect:eg-baro} - \ref{sect:eg-global}.  
 The other examples follow the same general structure as the tutorial  
 examples. However, they only include brief instructions in a text file  
 called {\it README}.  The examples are located in subdirectories under  
 the directory \textit{verification}. Each example is briefly described  
 below.  
   
 \subsection{Full list of model examples}  
   
 \begin{enumerate}  
     
 \item \textit{exp0} - single layer, ocean double gyre (barotropic with  
   free-surface). This experiment is described in detail in section  
   \ref{sect:eg-baro}.  
   
 \item \textit{exp1} - Four layer, ocean double gyre. This experiment  
   is described in detail in section \ref{sect:eg-baroc}.  
     
 \item \textit{exp2} - 4x4 degree global ocean simulation with steady  
   climatological forcing. This experiment is described in detail in  
   section \ref{sect:eg-global}.  
     
 \item \textit{exp4} - Flow over a Gaussian bump in open-water or  
   channel with open boundaries.  
     
 \item \textit{exp5} - Inhomogenously forced ocean convection in a  
   doubly periodic box.  
   
 \item \textit{front\_relax} - Relaxation of an ocean thermal front (test for  
 Gent/McWilliams scheme). 2D (Y-Z).  
   
 \item \textit{internal wave} - Ocean internal wave forced by open  
   boundary conditions.  
     
 \item \textit{natl\_box} - Eastern subtropical North Atlantic with KPP  
   scheme; 1 month integration  
     
 \item \textit{hs94.1x64x5} - Zonal averaged atmosphere using Held and  
   Suarez '94 forcing.  
     
 \item \textit{hs94.128x64x5} - 3D atmosphere dynamics using Held and  
   Suarez '94 forcing.  
     
 \item \textit{hs94.cs-32x32x5} - 3D atmosphere dynamics using Held and  
   Suarez '94 forcing on the cubed sphere.  
     
 \item \textit{aim.5l\_zon-ave} - Intermediate Atmospheric physics.  
   Global Zonal Mean configuration, 1x64x5 resolution.  
307        
308  \item \textit{aim.5l\_XZ\_Equatorial\_Slice} - Intermediate  \item \texttt{lsopt}: Line search code used for optimization.
   Atmospheric physics, equatorial Slice configuration.  2D (X-Z).  
309        
310  \item \textit{aim.5l\_Equatorial\_Channel} - Intermediate Atmospheric  \item \texttt{optim}: Interface between MITgcm and line search code.
   physics. 3D Equatorial Channel configuration.  
311        
 \item \textit{aim.5l\_LatLon} - Intermediate Atmospheric physics.  
   Global configuration, on latitude longitude grid with 128x64x5 grid  
   points ($2.8^\circ{\rm degree}$ resolution).  
     
 \item \textit{adjustment.128x64x1} Barotropic adjustment problem on  
   latitude longitude grid with 128x64 grid points ($2.8^\circ{\rm  
     degree}$ resolution).  
     
 \item \textit{adjustment.cs-32x32x1} Barotropic adjustment problem on  
   cube sphere grid with 32x32 points per face ( roughly $2.8^\circ{\rm  
     degree}$ resolution).  
     
 \item \textit{advect\_cs} Two-dimensional passive advection test on  
   cube sphere grid.  
     
 \item \textit{advect\_xy} Two-dimensional (horizontal plane) passive  
   advection test on Cartesian grid.  
     
 \item \textit{advect\_yz} Two-dimensional (vertical plane) passive  
   advection test on Cartesian grid.  
     
 \item \textit{carbon} Simple passive tracer experiment. Includes  
   derivative calculation. Described in detail in section  
   \ref{sect:eg-carbon-ad}.  
   
 \item \textit{flt\_example} Example of using float package.  
     
 \item \textit{global\_ocean.90x40x15} Global circulation with GM, flux  
   boundary conditions and poles.  
   
 \item \textit{global\_ocean\_pressure} Global circulation in pressure  
   coordinate (non-Boussinesq ocean model). Described in detail in  
   section \ref{sect:eg-globalpressure}.  
     
 \item \textit{solid-body.cs-32x32x1} Solid body rotation test for cube  
   sphere grid.  
   
 \end{enumerate}  
   
 \subsection{Directory structure of model examples}  
   
 Each example directory has the following subdirectories:  
   
 \begin{itemize}  
 \item \textit{code}: contains the code particular to the example. At a  
   minimum, this directory includes the following files:  
   
   \begin{itemize}  
   \item \textit{code/CPP\_EEOPTIONS.h}: declares CPP keys relative to  
     the ``execution environment'' part of the code. The default  
     version is located in \textit{eesupp/inc}.  
     
   \item \textit{code/CPP\_OPTIONS.h}: declares CPP keys relative to  
     the ``numerical model'' part of the code. The default version is  
     located in \textit{model/inc}.  
     
   \item \textit{code/SIZE.h}: declares size of underlying  
     computational grid.  The default version is located in  
     \textit{model/inc}.  
   \end{itemize}  
     
   In addition, other include files and subroutines might be present in  
   \textit{code} depending on the particular experiment. See Section 2  
   for more details.  
     
 \item \textit{input}: contains the input data files required to run  
   the example. At a minimum, the \textit{input} directory contains the  
   following files:  
   
   \begin{itemize}  
   \item \textit{input/data}: this file, written as a namelist,  
     specifies the main parameters for the experiment.  
     
   \item \textit{input/data.pkg}: contains parameters relative to the  
     packages used in the experiment.  
     
   \item \textit{input/eedata}: this file contains ``execution  
     environment'' data. At present, this consists of a specification  
     of the number of threads to use in $X$ and $Y$ under multithreaded  
     execution.  
   \end{itemize}  
     
   In addition, you will also find in this directory the forcing and  
   topography files as well as the files describing the initial state  
   of the experiment.  This varies from experiment to experiment. See  
   section 2 for more details.  
   
 \item \textit{results}: this directory contains the output file  
   \textit{output.txt} produced by the simulation example. This file is  
   useful for comparison with your own output when you run the  
   experiment.  
312  \end{itemize}  \end{itemize}
313    
 Once you have chosen the example you want to run, you are ready to  
 compile the code.  
   
314  \section[Building MITgcm]{Building the code}  \section[Building MITgcm]{Building the code}
315  \label{sect:buildingCode}  \label{sect:buildingCode}
316    \begin{rawhtml}
317  To compile the code, we use the {\em make} program. This uses a file  <!-- CMIREDIR:buildingCode: -->
318  ({\em Makefile}) that allows us to pre-process source files, specify  \end{rawhtml}
319  compiler and optimization options and also figures out any file  
320  dependencies. We supply a script ({\em genmake2}), described in  To compile the code, we use the \texttt{make} program. This uses a
321  section \ref{sect:genmake}, that automatically creates the {\em  file (\texttt{Makefile}) that allows us to pre-process source files,
322    Makefile} for you. You then need to build the dependencies and  specify compiler and optimization options and also figures out any
323    file dependencies. We supply a script (\texttt{genmake2}), described
324    in section \ref{sect:genmake}, that automatically creates the
325    \texttt{Makefile} for you. You then need to build the dependencies and
326  compile the code.  compile the code.
327    
328  As an example, let's assume that you want to build and run experiment  As an example, assume that you want to build and run experiment
329  \textit{verification/exp2}. The are multiple ways and places to  \texttt{verification/exp2}. The are multiple ways and places to
330  actually do this but here let's build the code in  actually do this but here let's build the code in
331  \textit{verification/exp2/input}:  \texttt{verification/exp2/build}:
332  \begin{verbatim}  \begin{verbatim}
333  % cd verification/exp2/input  % cd verification/exp2/build
334  \end{verbatim}  \end{verbatim}
335  First, build the {\em Makefile}:  First, build the \texttt{Makefile}:
336  \begin{verbatim}  \begin{verbatim}
337  % ../../../tools/genmake2 -mods=../code  % ../../../tools/genmake2 -mods=../code
338  \end{verbatim}  \end{verbatim}
339  The command line option tells {\em genmake} to override model source  The command line option tells \texttt{genmake} to override model source
340  code with any files in the directory {\em ./code/}.  code with any files in the directory \texttt{../code/}.
341    
342  On many systems, the {\em genmake2} program will be able to  On many systems, the \texttt{genmake2} program will be able to
343  automatically recognize the hardware, find compilers and other tools  automatically recognize the hardware, find compilers and other tools
344  within the user's path (``echo \$PATH''), and then choose an  within the user's path (``\texttt{echo \$PATH}''), and then choose an
345  appropriate set of options from the files contained in the {\em  appropriate set of options from the files (``optfiles'') contained in
346    tools/build\_options} directory.  Under some circumstances, a user  the \texttt{tools/build\_options} directory.  Under some
347  may have to create a new ``optfile'' in order to specify the exact  circumstances, a user may have to create a new ``optfile'' in order to
348  combination of compiler, compiler flags, libraries, and other options  specify the exact combination of compiler, compiler flags, libraries,
349  necessary to build a particular configuration of MITgcm.  In such  and other options necessary to build a particular configuration of
350  cases, it is generally helpful to read the existing ``optfiles'' and  MITgcm.  In such cases, it is generally helpful to read the existing
351  mimic their syntax.  ``optfiles'' and mimic their syntax.
352    
353  Through the MITgcm-support list, the MITgcm developers are willing to  Through the MITgcm-support list, the MITgcm developers are willing to
354  provide help writing or modifing ``optfiles''.  And we encourage users  provide help writing or modifing ``optfiles''.  And we encourage users
355  to post new ``optfiles'' (particularly ones for new machines or  to post new ``optfiles'' (particularly ones for new machines or
356  architectures) to the  architectures) to the
357  \begin{rawhtml} <A href=''mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}  \begin{rawhtml} <A href="mailto:MITgcm-support@mitgcm.org"> \end{rawhtml}
358  MITgcm-support@mitgcm.org  MITgcm-support@mitgcm.org
359  \begin{rawhtml} </A> \end{rawhtml}  \begin{rawhtml} </A> \end{rawhtml}
360  list.  list.
361    
362  To specify an optfile to {\em genmake2}, the syntax is:  To specify an optfile to \texttt{genmake2}, the syntax is:
363  \begin{verbatim}  \begin{verbatim}
364  % ../../../tools/genmake2 -mods=../code -of /path/to/optfile  % ../../../tools/genmake2 -mods=../code -of /path/to/optfile
365  \end{verbatim}  \end{verbatim}
366    
367  Once a {\em Makefile} has been generated, we create the dependencies:  Once a \texttt{Makefile} has been generated, we create the
368    dependencies with the command:
369  \begin{verbatim}  \begin{verbatim}
370  % make depend  % make depend
371  \end{verbatim}  \end{verbatim}
372  This modifies the {\em Makefile} by attaching a [long] list of files  This modifies the \texttt{Makefile} by attaching a (usually, long)
373  upon which other files depend. The purpose of this is to reduce  list of files upon which other files depend. The purpose of this is to
374  re-compilation if and when you start to modify the code. The {\tt make  reduce re-compilation if and when you start to modify the code. The
375    depend} command also creates links from the model source to this  {\tt make depend} command also creates links from the model source to
376  directory.  this directory.  It is important to note that the {\tt make depend}
377    stage will occasionally produce warnings or errors since the
378    dependency parsing tool is unable to find all of the necessary header
379    files (\textit{eg.}  \texttt{netcdf.inc}).  In these circumstances, it
380    is usually OK to ignore the warnings/errors and proceed to the next
381    step.
382    
383  Next compile the code:  Next one can compile the code using:
384  \begin{verbatim}  \begin{verbatim}
385  % make  % make
386  \end{verbatim}  \end{verbatim}
387  The {\tt make} command creates an executable called \textit{mitgcmuv}.  The {\tt make} command creates an executable called \texttt{mitgcmuv}.
388  Additional make ``targets'' are defined within the makefile to aid in  Additional make ``targets'' are defined within the makefile to aid in
389  the production of adjoint and other versions of MITgcm.  the production of adjoint and other versions of MITgcm.  On SMP
390    (shared multi-processor) systems, the build process can often be sped
391    up appreciably using the command:
392    \begin{verbatim}
393    % make -j 2
394    \end{verbatim}
395    where the ``2'' can be replaced with a number that corresponds to the
396    number of CPUs available.
397    
398  Now you are ready to run the model. General instructions for doing so are  Now you are ready to run the model. General instructions for doing so are
399  given in section \ref{sect:runModel}. Here, we can run the model with:  given in section \ref{sect:runModel}. Here, we can run the model by
400    first creating links to all the input files:
401    \begin{verbatim}
402    ln -s ../input/* .
403    \end{verbatim}
404    and then calling the executable with:
405  \begin{verbatim}  \begin{verbatim}
406  ./mitgcmuv > output.txt  ./mitgcmuv > output.txt
407  \end{verbatim}  \end{verbatim}
408  where we are re-directing the stream of text output to the file {\em  where we are re-directing the stream of text output to the file
409  output.txt}.  \texttt{output.txt}.
410    
411    \subsection{Building/compiling the code elsewhere}
412    
413    In the example above (section \ref{sect:buildingCode}) we built the
414    executable in the {\em input} directory of the experiment for
415    convenience. You can also configure and compile the code in other
416    locations, for example on a scratch disk with out having to copy the
417    entire source tree. The only requirement to do so is you have {\tt
418      genmake2} in your path or you know the absolute path to {\tt
419      genmake2}.
420    
421    The following sections outline some possible methods of organizing
422    your source and data.
423    
424    \subsubsection{Building from the {\em ../code directory}}
425    
426    This is just as simple as building in the {\em input/} directory:
427    \begin{verbatim}
428    % cd verification/exp2/code
429    % ../../../tools/genmake2
430    % make depend
431    % make
432    \end{verbatim}
433    However, to run the model the executable ({\em mitgcmuv}) and input
434    files must be in the same place. If you only have one calculation to make:
435    \begin{verbatim}
436    % cd ../input
437    % cp ../code/mitgcmuv ./
438    % ./mitgcmuv > output.txt
439    \end{verbatim}
440    or if you will be making multiple runs with the same executable:
441    \begin{verbatim}
442    % cd ../
443    % cp -r input run1
444    % cp code/mitgcmuv run1
445    % cd run1
446    % ./mitgcmuv > output.txt
447    \end{verbatim}
448    
449    \subsubsection{Building from a new directory}
450    
451    Since the {\em input} directory contains input files it is often more
452    useful to keep {\em input} pristine and build in a new directory
453    within {\em verification/exp2/}:
454    \begin{verbatim}
455    % cd verification/exp2
456    % mkdir build
457    % cd build
458    % ../../../tools/genmake2 -mods=../code
459    % make depend
460    % make
461    \end{verbatim}
462    This builds the code exactly as before but this time you need to copy
463    either the executable or the input files or both in order to run the
464    model. For example,
465    \begin{verbatim}
466    % cp ../input/* ./
467    % ./mitgcmuv > output.txt
468    \end{verbatim}
469    or if you tend to make multiple runs with the same executable then
470    running in a new directory each time might be more appropriate:
471    \begin{verbatim}
472    % cd ../
473    % mkdir run1
474    % cp build/mitgcmuv run1/
475    % cp input/* run1/
476    % cd run1
477    % ./mitgcmuv > output.txt
478    \end{verbatim}
479    
480    \subsubsection{Building on a scratch disk}
481    
482    Model object files and output data can use up large amounts of disk
483    space so it is often the case that you will be operating on a large
484    scratch disk. Assuming the model source is in {\em ~/MITgcm} then the
485    following commands will build the model in {\em /scratch/exp2-run1}:
486    \begin{verbatim}
487    % cd /scratch/exp2-run1
488    % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
489      -mods=~/MITgcm/verification/exp2/code
490    % make depend
491    % make
492    \end{verbatim}
493    To run the model here, you'll need the input files:
494    \begin{verbatim}
495    % cp ~/MITgcm/verification/exp2/input/* ./
496    % ./mitgcmuv > output.txt
497    \end{verbatim}
498    
499    As before, you could build in one directory and make multiple runs of
500    the one experiment:
501    \begin{verbatim}
502    % cd /scratch/exp2
503    % mkdir build
504    % cd build
505    % ~/MITgcm/tools/genmake2 -rootdir=~/MITgcm \
506      -mods=~/MITgcm/verification/exp2/code
507    % make depend
508    % make
509    % cd ../
510    % cp -r ~/MITgcm/verification/exp2/input run2
511    % cd run2
512    % ./mitgcmuv > output.txt
513    \end{verbatim}
514    
515    
516    \subsection{Using \texttt{genmake2}}
517    \label{sect:genmake}
518    
519    To compile the code, first use the program \texttt{genmake2} (located
520    in the \texttt{tools} directory) to generate a Makefile.
521    \texttt{genmake2} is a shell script written to work with all
522    ``sh''--compatible shells including bash v1, bash v2, and Bourne.
523    Internally, \texttt{genmake2} determines the locations of needed
524    files, the compiler, compiler options, libraries, and Unix tools.  It
525    relies upon a number of ``optfiles'' located in the
526    \texttt{tools/build\_options} directory.
527    
528    The purpose of the optfiles is to provide all the compilation options
529    for particular ``platforms'' (where ``platform'' roughly means the
530    combination of the hardware and the compiler) and code configurations.
531    Given the combinations of possible compilers and library dependencies
532    ({\it eg.}  MPI and NetCDF) there may be numerous optfiles available
533    for a single machine.  The naming scheme for the majority of the
534    optfiles shipped with the code is
535    \begin{center}
536      {\bf OS\_HARDWARE\_COMPILER }
537    \end{center}
538    where
539    \begin{description}
540    \item[OS] is the name of the operating system (generally the
541      lower-case output of the {\tt 'uname'} command)
542    \item[HARDWARE] is a string that describes the CPU type and
543      corresponds to output from the  {\tt 'uname -m'} command:
544      \begin{description}
545      \item[ia32] is for ``x86'' machines such as i386, i486, i586, i686,
546        and athlon
547      \item[ia64] is for Intel IA64 systems (eg. Itanium, Itanium2)
548      \item[amd64] is AMD x86\_64 systems
549      \item[ppc] is for Mac PowerPC systems
550      \end{description}
551    \item[COMPILER] is the compiler name (generally, the name of the
552      FORTRAN executable)
553    \end{description}
554    
555    In many cases, the default optfiles are sufficient and will result in
556    usable Makefiles.  However, for some machines or code configurations,
557    new ``optfiles'' must be written. To create a new optfile, it is
558    generally best to start with one of the defaults and modify it to suit
559    your needs.  Like \texttt{genmake2}, the optfiles are all written
560    using a simple ``sh''--compatible syntax.  While nearly all variables
561    used within \texttt{genmake2} may be specified in the optfiles, the
562    critical ones that should be defined are:
563    
564    \begin{description}
565    \item[FC] the FORTRAN compiler (executable) to use
566    \item[DEFINES] the command-line DEFINE options passed to the compiler
567    \item[CPP] the C pre-processor to use
568    \item[NOOPTFLAGS] options flags for special files that should not be
569      optimized
570    \end{description}
571    
572    For example, the optfile for a typical Red Hat Linux machine (``ia32''
573    architecture) using the GCC (g77) compiler is
574    \begin{verbatim}
575    FC=g77
576    DEFINES='-D_BYTESWAPIO -DWORDLENGTH=4'
577    CPP='cpp  -traditional -P'
578    NOOPTFLAGS='-O0'
579    #  For IEEE, use the "-ffloat-store" option
580    if test "x$IEEE" = x ; then
581        FFLAGS='-Wimplicit -Wunused -Wuninitialized'
582        FOPTIM='-O3 -malign-double -funroll-loops'
583    else
584        FFLAGS='-Wimplicit -Wunused -ffloat-store'
585        FOPTIM='-O0 -malign-double'
586    fi
587    \end{verbatim}
588    
589    If you write an optfile for an unrepresented machine or compiler, you
590    are strongly encouraged to submit the optfile to the MITgcm project
591    for inclusion.  Please send the file to the
592    \begin{rawhtml} <A href="mail-to:MITgcm-support@mitgcm.org"> \end{rawhtml}
593    \begin{center}
594      MITgcm-support@mitgcm.org
595    \end{center}
596    \begin{rawhtml} </A> \end{rawhtml}
597    mailing list.
598    
599    In addition to the optfiles, \texttt{genmake2} supports a number of
600    helpful command-line options.  A complete list of these options can be
601    obtained from:
602    \begin{verbatim}
603    % genmake2 -h
604    \end{verbatim}
605    
606    The most important command-line options are:
607    \begin{description}
608      
609    \item[\texttt{--optfile=/PATH/FILENAME}] specifies the optfile that
610      should be used for a particular build.
611      
612      If no "optfile" is specified (either through the command line or the
613      MITGCM\_OPTFILE environment variable), genmake2 will try to make a
614      reasonable guess from the list provided in {\em
615        tools/build\_options}.  The method used for making this guess is
616      to first determine the combination of operating system and hardware
617      (eg. "linux\_ia32") and then find a working FORTRAN compiler within
618      the user's path.  When these three items have been identified,
619      genmake2 will try to find an optfile that has a matching name.
620      
621    \item[\texttt{--pdefault='PKG1 PKG2 PKG3 ...'}] specifies the default
622      set of packages to be used.  The normal order of precedence for
623      packages is as follows:
624      \begin{enumerate}
625      \item If available, the command line (\texttt{--pdefault}) settings
626        over-rule any others.
627    
628      \item Next, \texttt{genmake2} will look for a file named
629        ``\texttt{packages.conf}'' in the local directory or in any of the
630        directories specified with the \texttt{--mods} option.
631        
632      \item Finally, if neither of the above are available,
633        \texttt{genmake2} will use the \texttt{/pkg/pkg\_default} file.
634      \end{enumerate}
635      
636    \item[\texttt{--pdepend=/PATH/FILENAME}] specifies the dependency file
637      used for packages.
638      
639      If not specified, the default dependency file {\em pkg/pkg\_depend}
640      is used.  The syntax for this file is parsed on a line-by-line basis
641      where each line containes either a comment ("\#") or a simple
642      "PKGNAME1 (+|-)PKGNAME2" pairwise rule where the "+" or "-" symbol
643      specifies a "must be used with" or a "must not be used with"
644      relationship, respectively.  If no rule is specified, then it is
645      assumed that the two packages are compatible and will function
646      either with or without each other.
647      
648    \item[\texttt{--adof=/path/to/file}] specifies the "adjoint" or
649      automatic differentiation options file to be used.  The file is
650      analogous to the ``optfile'' defined above but it specifies
651      information for the AD build process.
652      
653      The default file is located in {\em
654        tools/adjoint\_options/adjoint\_default} and it defines the "TAF"
655      and "TAMC" compilers.  An alternate version is also available at
656      {\em tools/adjoint\_options/adjoint\_staf} that selects the newer
657      "STAF" compiler.  As with any compilers, it is helpful to have their
658      directories listed in your {\tt \$PATH} environment variable.
659      
660    \item[\texttt{--mods='DIR1 DIR2 DIR3 ...'}] specifies a list of
661      directories containing ``modifications''.  These directories contain
662      files with names that may (or may not) exist in the main MITgcm
663      source tree but will be overridden by any identically-named sources
664      within the ``MODS'' directories.
665      
666      The order of precedence for this "name-hiding" is as follows:
667      \begin{itemize}
668      \item ``MODS'' directories (in the order given)
669      \item Packages either explicitly specified or provided by default
670        (in the order given)
671      \item Packages included due to package dependencies (in the order
672        that that package dependencies are parsed)
673      \item The "standard dirs" (which may have been specified by the
674        ``-standarddirs'' option)
675      \end{itemize}
676      
677    \item[\texttt{--mpi}] This option enables certain MPI features (using
678      CPP \texttt{\#define}s) within the code and is necessary for MPI
679      builds (see Section \ref{sect:mpi-build}).
680      
681    \item[\texttt{--make=/path/to/gmake}] Due to the poor handling of
682      soft-links and other bugs common with the \texttt{make} versions
683      provided by commercial Unix vendors, GNU \texttt{make} (sometimes
684      called \texttt{gmake}) should be preferred.  This option provides a
685      means for specifying the make executable to be used.
686      
687    \item[\texttt{--bash=/path/to/sh}] On some (usually older UNIX)
688      machines, the ``bash'' shell is unavailable.  To run on these
689      systems, \texttt{genmake2} can be invoked using an ``sh'' (that is,
690      a Bourne, POSIX, or compatible) shell.  The syntax in these
691      circumstances is:
692      \begin{center}
693        \texttt{\%  /bin/sh genmake2 -bash=/bin/sh [...options...]}
694      \end{center}
695      where \texttt{/bin/sh} can be replaced with the full path and name
696      of the desired shell.
697    
698    \end{description}
699    
700    
701    \subsection{Building with MPI}
702    \label{sect:mpi-build}
703    
704    Building MITgcm to use MPI libraries can be complicated due to the
705    variety of different MPI implementations available, their dependencies
706    or interactions with different compilers, and their often ad-hoc
707    locations within file systems.  For these reasons, its generally a
708    good idea to start by finding and reading the documentation for your
709    machine(s) and, if necessary, seeking help from your local systems
710    administrator.
711    
712    The steps for building MITgcm with MPI support are:
713    \begin{enumerate}
714      
715    \item Determine the locations of your MPI-enabled compiler and/or MPI
716      libraries and put them into an options file as described in Section
717      \ref{sect:genmake}.  One can start with one of the examples in:
718      \begin{rawhtml} <A
719        href="http://mitgcm.org/viewvc/MITgcm/MITgcm/tools/build_options/">
720      \end{rawhtml}
721      \begin{center}
722        \texttt{MITgcm/tools/build\_options/}
723      \end{center}
724      \begin{rawhtml} </A> \end{rawhtml}
725      such as \texttt{linux\_ia32\_g77+mpi\_cg01} or
726      \texttt{linux\_ia64\_efc+mpi} and then edit it to suit the machine at
727      hand.  You may need help from your user guide or local systems
728      administrator to determine the exact location of the MPI libraries.
729      If libraries are not installed, MPI implementations and related
730      tools are available including:
731      \begin{itemize}
732      \item \begin{rawhtml} <A
733          href="http://www-unix.mcs.anl.gov/mpi/mpich/">
734        \end{rawhtml}
735        MPICH
736        \begin{rawhtml} </A> \end{rawhtml}
737    
738      \item \begin{rawhtml} <A
739          href="http://www.lam-mpi.org/">
740        \end{rawhtml}
741        LAM/MPI
742        \begin{rawhtml} </A> \end{rawhtml}
743    
744      \item \begin{rawhtml} <A
745          href="http://www.osc.edu/~pw/mpiexec/">
746        \end{rawhtml}
747        MPIexec
748        \begin{rawhtml} </A> \end{rawhtml}
749      \end{itemize}
750      
751    \item Build the code with the \texttt{genmake2} \texttt{-mpi} option
752      (see Section \ref{sect:genmake}) using commands such as:
753    {\footnotesize \begin{verbatim}
754      %  ../../../tools/genmake2 -mods=../code -mpi -of=YOUR_OPTFILE
755      %  make depend
756      %  make
757    \end{verbatim} }
758      
759    \item Run the code with the appropriate MPI ``run'' or ``exec''
760      program provided with your particular implementation of MPI.
761      Typical MPI packages such as MPICH will use something like:
762    \begin{verbatim}
763      %  mpirun -np 4 -machinefile mf ./mitgcmuv
764    \end{verbatim}
765      Sightly more complicated scripts may be needed for many machines
766      since execution of the code may be controlled by both the MPI
767      library and a job scheduling and queueing system such as PBS,
768      LoadLeveller, Condor, or any of a number of similar tools.  A few
769      example scripts (those used for our \begin{rawhtml} <A
770        href="http://mitgcm.org/testing.html"> \end{rawhtml}regular
771      verification runs\begin{rawhtml} </A> \end{rawhtml}) are available
772      at:
773      \begin{rawhtml} <A
774        href="http://mitgcm.org/viewvc/MITgcm/MITgcm_contrib/test_scripts/">
775      \end{rawhtml}
776      {\footnotesize \tt
777        http://mitgcm.org/viewvc/MITgcm/MITgcm\_contrib/test\_scripts/ }
778      \begin{rawhtml} </A> \end{rawhtml}
779    
780    \end{enumerate}
781    
782    An example of the above process on the MITgcm cluster (``cg01'') using
783    the GNU g77 compiler and the mpich MPI library is:
784    
785    {\footnotesize \begin{verbatim}
786      %  cd MITgcm/verification/exp5
787      %  mkdir build
788      %  cd build
789      %  ../../../tools/genmake2 -mpi -mods=../code \
790           -of=../../../tools/build_options/linux_ia32_g77+mpi_cg01
791      %  make depend
792      %  make
793      %  cd ../input
794      %  /usr/local/pkg/mpi/mpi-1.2.4..8a-gm-1.5/g77/bin/mpirun.ch_gm \
795           -machinefile mf --gm-kill 5 -v -np 2  ../build/mitgcmuv
796    \end{verbatim} }
797    
798  \section[Running MITgcm]{Running the model in prognostic mode}  \section[Running MITgcm]{Running the model in prognostic mode}
799  \label{sect:runModel}  \label{sect:runModel}
800    \begin{rawhtml}
801    <!-- CMIREDIR:runModel: -->
802    \end{rawhtml}
803    
804  If compilation finished succesfuully (section \ref{sect:buildingCode})  If compilation finished succesfully (section \ref{sect:buildingCode})
805  then an executable called \texttt{mitgcmuv} will now exist in the  then an executable called \texttt{mitgcmuv} will now exist in the
806  local directory.  local directory.
807    
808  To run the model as a single process (ie. not in parallel) simply  To run the model as a single process (\textit{ie.} not in parallel)
809  type:  simply type:
810  \begin{verbatim}  \begin{verbatim}
811  % ./mitgcmuv  % ./mitgcmuv
812  \end{verbatim}  \end{verbatim}
# Line 579  do!). The above command will spew out ma Line 816  do!). The above command will spew out ma
816  your screen.  This output contains details such as parameter values as  your screen.  This output contains details such as parameter values as
817  well as diagnostics such as mean Kinetic energy, largest CFL number,  well as diagnostics such as mean Kinetic energy, largest CFL number,
818  etc. It is worth keeping this text output with the binary output so we  etc. It is worth keeping this text output with the binary output so we
819  normally re-direct the {\em stdout} stream as follows:  normally re-direct the \texttt{stdout} stream as follows:
820  \begin{verbatim}  \begin{verbatim}
821  % ./mitgcmuv > output.txt  % ./mitgcmuv > output.txt
822  \end{verbatim}  \end{verbatim}
823    In the event that the model encounters an error and stops, it is very
824  For the example experiments in {\em verification}, an example of the  helpful to include the last few line of this \texttt{output.txt} file
825  output is kept in {\em results/output.txt} for comparison. You can compare  along with the (\texttt{stderr}) error message within any bug reports.
826  your {\em output.txt} with this one to check that the set-up works.  
827    For the example experiments in \texttt{verification}, an example of the
828    output is kept in \texttt{results/output.txt} for comparison. You can
829    compare your \texttt{output.txt} with the corresponding one for that
830    experiment to check that the set-up works.
831    
832    
833    
834  \subsection{Output files}  \subsection{Output files}
835    
836  The model produces various output files. At a minimum, the instantaneous  The model produces various output files and, when using \texttt{mnc},
837  ``state'' of the model is written out, which is made of the following files:  sometimes even directories.  Depending upon the I/O package(s)
838    selected at compile time (either \texttt{mdsio} or \texttt{mnc} or
839    both as determined by \texttt{code/packages.conf}) and the run-time
840    flags set (in \texttt{input/data.pkg}), the following output may
841    appear.
842    
843    
844    \subsubsection{MDSIO output files}
845    
846    The ``traditional'' output files are generated by the \texttt{mdsio}
847    package.  At a minimum, the instantaneous ``state'' of the model is
848    written out, which is made of the following files:
849    
850  \begin{itemize}  \begin{itemize}
851  \item \textit{U.00000nIter} - zonal component of velocity field (m/s and $>  \item \texttt{U.00000nIter} - zonal component of velocity field (m/s
852  0 $ eastward).    and positive eastward).
853    
854  \item \textit{V.00000nIter} - meridional component of velocity field (m/s  \item \texttt{V.00000nIter} - meridional component of velocity field
855  and $> 0$ northward).    (m/s and positive northward).
856    
857  \item \textit{W.00000nIter} - vertical component of velocity field (ocean:  \item \texttt{W.00000nIter} - vertical component of velocity field
858  m/s and $> 0$ upward, atmosphere: Pa/s and $> 0$ towards increasing pressure    (ocean: m/s and positive upward, atmosphere: Pa/s and positive
859  i.e. downward).    towards increasing pressure i.e. downward).
860    
861  \item \textit{T.00000nIter} - potential temperature (ocean: $^{0}$C,  \item \texttt{T.00000nIter} - potential temperature (ocean:
862  atmosphere: $^{0}$K).    $^{\circ}\mathrm{C}$, atmosphere: $^{\circ}\mathrm{K}$).
863    
864  \item \textit{S.00000nIter} - ocean: salinity (psu), atmosphere: water vapor  \item \texttt{S.00000nIter} - ocean: salinity (psu), atmosphere: water
865  (g/kg).    vapor (g/kg).
866    
867  \item \textit{Eta.00000nIter} - ocean: surface elevation (m), atmosphere:  \item \texttt{Eta.00000nIter} - ocean: surface elevation (m),
868  surface pressure anomaly (Pa).    atmosphere: surface pressure anomaly (Pa).
869  \end{itemize}  \end{itemize}
870    
871  The chain \textit{00000nIter} consists of ten figures that specify the  The chain \texttt{00000nIter} consists of ten figures that specify the
872  iteration number at which the output is written out. For example, \textit{%  iteration number at which the output is written out. For example,
873  U.0000000300} is the zonal velocity at iteration 300.  \texttt{U.0000000300} is the zonal velocity at iteration 300.
874    
875  In addition, a ``pickup'' or ``checkpoint'' file called:  In addition, a ``pickup'' or ``checkpoint'' file called:
876    
877  \begin{itemize}  \begin{itemize}
878  \item \textit{pickup.00000nIter}  \item \texttt{pickup.00000nIter}
879  \end{itemize}  \end{itemize}
880    
881  is written out. This file represents the state of the model in a condensed  is written out. This file represents the state of the model in a condensed
# Line 631  form and is used for restarting the inte Line 883  form and is used for restarting the inte
883  there is an additional ``pickup'' file:  there is an additional ``pickup'' file:
884    
885  \begin{itemize}  \begin{itemize}
886  \item \textit{pickup\_cd.00000nIter}  \item \texttt{pickup\_cd.00000nIter}
887  \end{itemize}  \end{itemize}
888    
889  containing the D-grid velocity data and that has to be written out as well  containing the D-grid velocity data and that has to be written out as well
890  in order to restart the integration. Rolling checkpoint files are the same  in order to restart the integration. Rolling checkpoint files are the same
891  as the pickup files but are named differently. Their name contain the chain  as the pickup files but are named differently. Their name contain the chain
892  \textit{ckptA} or \textit{ckptB} instead of \textit{00000nIter}. They can be  \texttt{ckptA} or \texttt{ckptB} instead of \texttt{00000nIter}. They can be
893  used to restart the model but are overwritten every other time they are  used to restart the model but are overwritten every other time they are
894  output to save disk space during long integrations.  output to save disk space during long integrations.
895    
896    \subsubsection{MNC output files}
897    
898    Unlike the \texttt{mdsio} output, the \texttt{mnc}--generated output
899    is usually (though not necessarily) placed within a subdirectory with
900    a name such as \texttt{mnc\_test\_\${DATE}\_\${SEQ}}.  
901    
902  \subsection{Looking at the output}  \subsection{Looking at the output}
903    
904  All the model data are written according to a ``meta/data'' file format.  The ``traditional'' or mdsio model data are written according to a
905  Each variable is associated with two files with suffix names \textit{.data}  ``meta/data'' file format.  Each variable is associated with two files
906  and \textit{.meta}. The \textit{.data} file contains the data written in  with suffix names \texttt{.data} and \texttt{.meta}. The
907  binary form (big\_endian by default). The \textit{.meta} file is a  \texttt{.data} file contains the data written in binary form
908  ``header'' file that contains information about the size and the structure  (big\_endian by default). The \texttt{.meta} file is a ``header'' file
909  of the \textit{.data} file. This way of organizing the output is  that contains information about the size and the structure of the
910  particularly useful when running multi-processors calculations. The base  \texttt{.data} file. This way of organizing the output is particularly
911  version of the model includes a few matlab utilities to read output files  useful when running multi-processors calculations. The base version of
912  written in this format. The matlab scripts are located in the directory  the model includes a few matlab utilities to read output files written
913  \textit{utils/matlab} under the root tree. The script \textit{rdmds.m} reads  in this format. The matlab scripts are located in the directory
914  the data. Look at the comments inside the script to see how to use it.  \texttt{utils/matlab} under the root tree. The script \texttt{rdmds.m}
915    reads the data. Look at the comments inside the script to see how to
916    use it.
917    
918  Some examples of reading and visualizing some output in {\em Matlab}:  Some examples of reading and visualizing some output in {\em Matlab}:
919  \begin{verbatim}  \begin{verbatim}
# Line 670  Some examples of reading and visualizing Line 930  Some examples of reading and visualizing
930  >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end  >> for n=1:11; imagesc(eta(:,:,n)');axis ij;colorbar;pause(.5);end
931  \end{verbatim}  \end{verbatim}
932    
933    Similar scripts for netCDF output (\texttt{rdmnc.m}) are available and
934    they are described in Section \ref{sec:pkg:mnc}.
935    
936    The MNC output files are all in the ``self-describing'' netCDF
937    format and can thus be browsed and/or plotted using tools such as:
938    \begin{itemize}
939    \item \texttt{ncdump} is a utility which is typically included
940      with every netCDF install:
941      \begin{rawhtml} <A href="http://www.unidata.ucar.edu/packages/netcdf/"> \end{rawhtml}
942    \begin{verbatim}
943    http://www.unidata.ucar.edu/packages/netcdf/
944    \end{verbatim}
945      \begin{rawhtml} </A> \end{rawhtml} and it converts the netCDF
946      binaries into formatted ASCII text files.
947    
948    \item \texttt{ncview} utility is a very convenient and quick way
949      to plot netCDF data and it runs on most OSes:
950      \begin{rawhtml} <A href="http://meteora.ucsd.edu/~pierce/ncview_home_page.html"> \end{rawhtml}
951    \begin{verbatim}
952    http://meteora.ucsd.edu/~pierce/ncview_home_page.html
953    \end{verbatim}
954      \begin{rawhtml} </A> \end{rawhtml}
955      
956    \item MatLAB(c) and other common post-processing environments provide
957      various netCDF interfaces including:
958      \begin{rawhtml} <A href="http://mexcdf.sourceforge.net/"> \end{rawhtml}
959    \begin{verbatim}
960    http://mexcdf.sourceforge.net/
961    \end{verbatim}
962      \begin{rawhtml} </A> \end{rawhtml}
963      \begin{rawhtml} <A href="http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html"> \end{rawhtml}
964    \begin{verbatim}
965    http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html
966    \end{verbatim}
967      \begin{rawhtml} </A> \end{rawhtml}
968    \end{itemize}
969    

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