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1 molod 1.1 \subsection{Diagnostics--A Flexible Infrastructure}
2     \label{sec:pkg:diagnostics}
3     \begin{rawhtml}
4     <!-- CMIREDIR:package_diagnostics: -->
5     \end{rawhtml}
6    
7     \subsubsection{Introduction}
8    
9     \noindent
10     This section of the documentation describes the Diagnostics package available within
11     the GCM. A large selection of model diagnostics is available for output.
12     In addition to the diagnostic quantities pre-defined in the GCM, there exists
13     the option, in any experiment, to define a new diagnostic quantity and include it
14     as part of the diagnostic output with the addition of a single subroutine call in the
15     routine where the field is computed. As a matter of philosophy, no diagnostic is enabled
16     as default, thus each user must specify the exact diagnostic information required for an
17     experiment. This is accomplished by enabling the specific diagnostic of interest cataloged
18     in the Diagnostic Menu (see Section \ref{sec:diagnostics:menu}). Instructions for enabling
19     diagnostic output and defining new diagnostic quantities are found in Section
20     \ref{sec:diagnostics:usersguide} of this document.
21    
22     \noindent
23     The Diagnostic Menu in this section of the manual is a listing of diagnostic quantities available
24     within the main (dynamics) part of the GCM. Additional diagnostic quantities, defined within the
25     different GCM packages, are available and are listed in the diagnostic menu subsection of
26     the manual section associated with each relevant package. Once a diagnostic is enabled, the
27     GCM will continually increment an array specifically allocated for that diagnostic whenever the
28     appropriate quantity is computed. A counter is defined which records how many times each diagnostic
29     quantity has been incremented. Several special diagnostics are included in the menu. Quantities
30     refered to as ``Counter Diagnostics'', are defined for selected diagnostics which record the
31     frequency at which a diagnostic is incremented separately for each model grid location.
32     Quantitied refered to as ``User Diagnostics'' are included in the menu to facilitate
33     defining new diagnostics for a particular experiment.
34    
35     \subsubsection{Equations}
36     Not relevant.
37    
38     \subsubsection{Key Subroutines and Parameters}
39     \label{sec:diagnostics:diagover}
40    
41     \noindent
42     There are several utilities within the GCM available to users to enable, disable,
43     clear, write and retrieve model diagnostics, and may be called from any routine.
44     The available utilities and the CALL sequences are listed below.
45    
46     \noindent
47     {\bf diagnostics\_fill}: This is the main user interface routine to the diagnostics
48     package. This routine will increment the specified diagnostic quantity with a field
49     sent through the argument list.
50    
51     \noindent
52     \begin{tabbing}
53     XXXXXXXXX\=XXXXXX\= \kill
54     \> call diagnostics\_fill (arrayin, chardiag, levflg, nlevs, \\
55     \> bibjflg, bi, bj, myThid) \\
56     \\
57     where \> arrayin \>= Field to increment diagnostics array \\
58     \> chardiag \>= Character *8 expression for diag to fill \\
59     \> levflg \>= Integer flag for vertical levels: \\
60     \> \>= 0 indicates multiple (nlevs) levels incremented \\
61     \> \>= -1 indicates multiple (nlevs) levels incremented, \\
62     \> \> but in reverse vertical order \\
63     \> \> positive integer - WHICH single level to increment. \\
64     \> nlevs \>= indicates Number of levels to be filled (1 if levflg gt 0) \\
65     \> bibjflg \>= Integer flag to indicate instructions for bi bj loop \\
66     \> \>= 0 indicates that the bi-bj loop must be done here \\
67     \> \>= 1 indicates that the bi-bj loop is done OUTSIDE \\
68     \> \>= 2 indicates that the bi-bj loop is done OUTSIDE \\
69     \> \> AND that we have been sent a local array \\
70     \> \> AND that the array has the shadow regions \\
71     \> \>= 3 indicates that the bi-bj loop is done OUTSIDE \\
72     \> \> AND that we have been sent a local array \\
73     \> \> AND that the array has no shadow regions \\
74     \> bi \>= X-direction process(or) number - used for bibjflg=1-3 \\
75     \> bj \>= Y-direction process(or) number - used for bibjflg=1-3 \\
76     \> myThid \>= Current Thread number \\
77     \end{tabbing}
78    
79     \noindent
80     {\bf diagnostics\_scale\_fill}: This is a possible alternative routine to
81     diagnostics\_fill which performs the same functions and has an additional option
82     to scale the field before filling or raise the field to a power before filling.
83    
84     \noindent
85     \begin{tabbing}
86     XXXXXXXXX\=XXXXXX\= \kill
87     \> call diagnostics\_scale\_fill (arrayin, scalefactor, power, chardiag, \\
88     \> levflg, nlevs, bibjflg, bi, bj, myThid) \\
89     \\
90     where \> All the arguments are the same as for diagnostics\_fill with the addition of: \\
91     \> scalefactor \>= Factor to scale field \\
92     \> power \>= Integer power to which to raise the input field \\
93     \end{tabbing}
94    
95     \noindent
96     {\bf diagnostics\_is\_on}: Function call to inquire whether a diagnostic is active
97     and can be incremented. Useful when there is a computation that must be done locally
98     before a call to diagnostics\_fill. The call sequence:
99    
100     \noindent
101     \begin{tabbing}
102     XXXXXXXXX\=XXXXXX\= \kill
103     \> flag = diagnostics\_is\_on( diagName, myThid )
104     \\
105     where \> diagName \>= Character *8 expression for diagnostic \\
106     \> myThid \>= Current Thread number \\
107     \end{tabbing}
108    
109     \noindent
110     {\bf diagnostics\_get\_pointers}: This subroutine retrieves the value of a the diagnostics
111     pointers that other routines require as input - can be useful if the diagnostics common
112     blocks are not local to a routine.
113    
114     \noindent
115     \begin{tabbing}
116     XXXXXXXXX\=XXXXXX\= \kill
117     \> call diagnostics\_get\_pointers( diagName, ipoint, jpoint, myThid )
118     \\
119     where \> diagName \>= Character *8 expression of diagnostic \\
120     \> ipoint \>= Pointer into qdiag array - from idiag array in common \\
121     \> jpoint \>= Pointer into diagnostics menu - from jdiag array in common \\
122     \> myThid \>= Current Thread number \\
123     \end{tabbing}
124    
125     \noindent
126     {\bf getdiag}: This subroutine retrieves the value of a model diagnostic. This routine
127     is particulary useful when called from a user output routine, although it can be called
128     from any routine. This routine returns the time-averaged value of the diagnostic by
129     dividing the current accumulated diagnostic value by its corresponding counter. This
130     routine does not change the value of the diagnostic itself, that is, it does not replace
131     the diagnostic with its time-average. The calling sequence for this routine is givin by:
132    
133     \noindent
134     \begin{tabbing}
135     XXXXXXXXX\=XXXXXX\= \kill
136     \> call getdiag (lev, undef, qtmp, ipoint, mate, bi, bj, myThid) \\
137     \\
138     where \> lev \>= Model Level at which the diagnostic is desired \\
139     \> undef \>= Fill value to be used when diagnostic is undefined \\
140     \> qtmp \>= Time-Averaged Diagnostic Output \\
141     \> ipoint \>= Pointer into qdiag array - from idiag array in common \\
142     \> mate \>= Diagnostic mate pointer number \\
143     \> bi \>= X-direction process(or) number \\
144     \> bj \>= Y-direction process(or) number \\
145     \> myThid \>= Current Thread number \\
146     \end{tabbing}
147    
148     \noindent
149     {\bf diagnostics\_add2list}: This subroutine enables a diagnostic from the Diagnostic Menu, meaning
150     that space is allocated for the diagnostic and the model routines will increment the
151     diagnostic value during execution. This routine is the underlying interface routine
152     for defining a new permanent diagnostic in the main model or in a package. The calling sequence is:
153    
154     \noindent
155     \begin{tabbing}
156     XXXXXXXXX\=XXXXXX\= \kill
157     \> call diagnostics\_add2list( diagNum,diagName, diagCode, \\
158     \> diagUnits, diagTitle, myThid ) \\
159     \\
160     where \> diagNum \>=Diagnostic number - Output from routine \\
161     \> diagName \>=character*8 diagnostic name \\
162     \> diagCode \>=character*16 parsing code (see description of gdiag below) \\
163     \> diagUnits \>=Diagnostic units (character*16) \\
164     \> diagTitle \>=Diagnostic title or long name (up to character*80) \\
165     \> myThid \>=Current Thread number \\
166     \end{tabbing}
167    
168     \noindent
169     {\bf clrdiag}: This subroutine initializes the values of model diagnostics to zero, and is
170     particularly useful when called from user output routines to re-initialize diagnostics
171     during the run. The calling sequence is:
172    
173     \noindent
174     \begin{tabbing}
175     XXXXXXXXX\=XXXXXX\= \kill
176     \> call diagnostics\_clrdiag (jpoint, ipoint, myThid) \\
177     \\
178     where \> jpoint \>= Diagnostic number from menu - from jdiag array \\
179     ipoint \>= Pointer number into qdiag array - from idiag array \\
180     \> myThid \>=Current Thread number \\
181     \end{tabbing}
182    
183     \noindent
184     The diagnostics are computed at various times and places within the GCM. Because the
185     MIT GCM may employ a staggered grid, diagnostics may be computed at grid box centers,
186     corners, or edges, and at the middle or edge in the vertical. Some diagnostics are scalars,
187     while others are components of vectors. An internal array is defined which contains
188     information concerning various grid attributes of each diagnostic. The GDIAG
189     array (in common block \\diagnostics in file DIAGNOSTICS.h) is internally defined as a
190     character*8 variable, and is equivalenced to a character*1 "parse" array in output in
191     order to extract the grid-attribute information. The GDIAG array is described in
192     Table \ref{tab:diagnostics:gdiag.tabl}.
193    
194     \begin{table}
195     \caption{Diagnostic Parsing Array}
196     \label{tab:diagnostics:gdiag.tabl}
197     \begin{center}
198     \begin{tabular}{ |c|c|l| }
199     \hline
200     \multicolumn{3}{|c|}{\bf Diagnostic Parsing Array} \\
201     \hline
202     \hline
203     Array & Value & Description \\
204     \hline
205     parse(1) & $\rightarrow$ S & Scalar Diagnostic \\
206     & $\rightarrow$ U & U-vector component Diagnostic \\
207     & $\rightarrow$ V & V-vector component Diagnostic \\ \hline
208     parse(2) & $\rightarrow$ U & C-Grid U-Point \\
209     & $\rightarrow$ V & C-Grid V-Point \\
210     & $\rightarrow$ M & C-Grid Mass Point \\
211     & $\rightarrow$ Z & C-Grid Vorticity (Corner) Point \\ \hline
212     parse(3) & $\rightarrow$ R & Not Currently in Use \\ \hline
213     parse(4) & $\rightarrow$ P & Positive Definite Diagnostic \\ \hline
214     parse(5) & $\rightarrow$ C & Counter Diagnostic \\
215     & $\rightarrow$ D & Disabled Diagnostic for output \\ \hline
216     parse(6-8) & $\rightarrow$ C & 3-digit integer corresponding to \\
217     & & vector or counter component mate \\ \hline
218     \end{tabular}
219     \addcontentsline{lot}{section}{Table 3: Diagnostic Parsing Array}
220     \end{center}
221     \end{table}
222    
223    
224     \noindent
225     As an example, consider a diagnostic whose associated GDIAG parameter is equal
226     to ``UU 002''. From GDIAG we can determine that this diagnostic is a
227     U-vector component located at the C-grid U-point.
228     Its corresponding V-component diagnostic is located in Diagnostic \# 002.
229    
230     \noindent
231     In this way, each Diagnostic in the model has its attributes (ie. vector or scalar,
232     C-grid location, etc.) defined internally. The Output routines use this information
233     in order to determine what type of transformations need to be performed. Any
234     interpolations are done at the time of output rather than during each model step.
235     In this way the User has flexibility in determining the type of gridded data which
236     is output.
237    
238     \subsubsection{Usage Notes}
239     \label{sec:diagnostics:usersguide}
240    
241     \noindent
242     To use the diagnostics package, other than enabling it in packages.conf
243     and turning the usediagnostics flag in data.pkg to .TRUE., there are two
244     further steps the user must take to enable the diagnostics package for
245     output of quantities that are already defined in the GCM under an experiment's
246     configuration of packages. A namelist must be supplied in the run directory
247     called data.diagnostics, and the file DIAGNOSTICS\_SIZE.h must be included in the
248     code directory. The steps for defining a new (permanent or experiment-specific
249     temporary) diagnostic quantity will be outlined later.
250    
251     \noindent The namelist will activate a user-defined list of diagnostics quantities
252     to be computed, specify the frequency and type of output, the number of levels, and
253     the name of all the separate output files. A sample data.diagnostics namelist file:
254    
255     \noindent
256     $\#$ Diagnostic Package Choices \\
257     $\&$diagnostics\_list \\
258     frequency(1) = 86400., \ \\
259     levels(1,1) = 1., \ \\
260     fields(1,1) = 'RSURF ', \ \\
261     filename(1) = 'surface', \ \\
262     frequency(2) = 86400., \ \\
263     levels(1,2) = 1.,2.,3.,4.,5., \ \\
264     fields(1,2) = 'UVEL ','VVEL ', \ \\
265     filename(2) = 'diagout1', \ \\
266     frequency(3) = 3600., \ \\
267     fields(1,3) = 'UVEL ','VVEL ','PRESSURE', \ \\
268     filename(3) = 'diagout2', \ \\
269     fileflags(3) = ' P1 ', \ \\
270     $\&$end \ \\
271    
272     \noindent
273     In this example, there are two output files that will be generated
274     for each tile and for each output time. The first set of output files
275     has the prefix diagout1, does time averaging every 86400. seconds,
276     (frequency is 86400.), and will write fields which are multiple-level
277     fields at output levels 1-5. The names of diagnostics quantities are
278     UVEL and VVEL. The second set of output files
279     has the prefix diagout2, does time averaging every 3600. seconds,
280     includes fields which are multiple-level fields, levels output are 1-5,
281     and the names of diagnostics quantities are THETA and SALT.
282    
283     \noindent
284     The user must assure that enough computer memory is allocated for the diagnostics
285     and the output streams selected for a particular experiment. This is acomplished by
286     modifying the file DIAGNOSTICS\_SIZE.h and including it in the experiment code directory.
287     The parameters that should be checked are called numdiags, numlists, numperlist, and
288     diagSt\_size.
289    
290     \noindent numdiags (and diagSt\_size): \\
291     \noindent All GCM diagnostic quantities are stored in the single diagnostic array QDIAG
292     which is located in the file \\ \filelink{pkg/diagnostics/DIAGNOSTICS.h}{pkg-diagnostics-DIAGNOSTICS.h}.\\
293     and has the form:\\
294     common /diagnostics/ qdiag(1-Olx,sNx+Olx,1-Olx,sNx+Olx,numdiags,Nsx,Nsy) \\
295     \noindent
296     The first two-dimensions of qdiag correspond to the horizontal dimension of a given diagnostic,
297     and the third dimension of qdiag is used to identify diagnostic fields and levels combined. In
298     order to minimize the memory requirement of the model for diagnostics, the default GCM
299     executable is compiled with room for only one horizontal diagnostic array, or with
300     numdiags set to Nr. In order for the User to enable more than 1 three-dimensional diagnostic,
301     the size of the diagnostics common must be expanded to accomodate the desired diagnostics.
302     This can be accomplished by manually changing the parameter numdiags in the
303     file \filelink{pkg/diagnostics/DIAGNOSTICS\_SIZE.h}{pkg-diagnostics-DIAGNOSTICS\_SIZE.h}.
304     numdiags should be set greater than or equal to the sum of all the diagnostics activated
305     for output each multiplied by the number of levels defined for that diagnostic quantity.
306     For the above example, there are 4 multiple level fields, which the diagnostics menu
307     (see below) indicates are defined at the GCM vertical resolution, Nr. The value of
308     numdiag in DIAGNOSTICS\_SIZE.h would therefore be equal to 4*Nr, or, say 40 if $Nr=10$.
309    
310     \noindent numlists and numperlist: \\
311     \noindent The parameter numlists must be set greater than or equal to the number of
312     separate output streams that the user specifies in the namelist file data.diagnostics.
313     The parameter numperlist corresponds to the number of diagnostics requested in each
314     output stream.
315    
316     \noindent
317     In order to define and include as part of the diagnostic output any field
318     that is desired for a particular experiment, two steps must be taken. The
319     first is to enable the ``User Diagnostic'' in data.diagnostics. This is
320     accomplished by adding one of the ``User Diagnostic'' field names (UDIAG1 through
321     UDIAG10, for multi-level fields, or SDIAG1 through SDIAG10 for single level
322     fields) to the data.diagnostics namelist in one of the output streams. These
323     fields are listed in the diagnostics menu. The second step is to
324     add a call to diagnostics\_fill from the subroutine in which the quantity
325     desired for diagnostic output is computed.
326    
327     \noindent
328     In order to add a new diagnostic to the permanent set of diagnostics that the
329     main model or any package contains as part of its diagnostics menu, the subroutine
330     diagnostics\_add2list should be called during the initialization phase of the
331     main model or package. For the main model, the call should be made from
332     subroutine diagnostics\_main\_init, and for a package, the call should probably
333     be made from somewhere in the packages\_init\_fixed sequence (probaby from inside
334     the particular package's init\_fixed routine). A typical code sequence to set the
335     input arguments to diagnostics\_add2list would look like:
336    
337     \noindent
338     \begin{tabbing}
339     XXXXXXXXX\=XXXXXX\= \kill
340     \> diagName = 'THETA ' \\
341     \> diagTitle = 'Potential Temperature (degC,K)' \\
342     \> diagUnits = 'Degrees K ' \\
343     \> diagCode = 'SM MR ' \\
344     \> CALL DIAGNOSTICS\_ADD2LIST( diagNum, \\
345     \> I diagName, diagCode, diagUnits, diagTitle, myThid ) \\
346     \\
347     \end{tabbing}
348    
349     \noindent If the new diagnostic quantity is associated with either a vector
350     pair or a diagnostic counter, the diagCode argument must be filled with the
351     proper index for the ``mate''. The output argument from diagnostics\_add2list
352     that is called diagNum here contains a running total of the number of diagnostics
353     defined in the code up to any point during the run. The sequence number for the
354     next two diagnostics defined (the two components of the vector pair, for instance)
355     will be diagNum+1 and diagNum+2. The definition of the first component of the vector
356     pair must fill the ``mate'' segment of the diagCode as diagnostic number diagNum+2.
357     Since the subroutine increments diagNum, the definition of the second component of
358     the vector fills the ``mate'' part of diagCode with diagNum. A code sequence for
359     this case would look like:
360    
361     \noindent
362     \begin{tabbing}
363     XXXXXXXXX\=XXXXXX\= \kill
364     \> diagName = 'UVEL ' \\
365     \> diagTitle = 'Zonal Velocity ' \\
366     \> diagUnits = 'm / sec ' \\
367     \> diagCode = 'SM MR ' \\
368     \> write(diagCode,'(A,I3.3,A)') 'VV ', diagNum+2 ,'MR ' \\
369     \> call diagnostics\_add2list( diagNum, \\
370     \> I diagName, diagCode, diagUnits, diagTitle, myThid ) \\
371     \> diagName = 'VVEL ' \\
372     \> diagTitle = 'Meridional Velocity ' \\
373     \> diagUnits = 'm / sec ' \\
374     \> diagCode = 'SM MR ' \\
375     \> write(diagCode,'(A,I3.3,A)') 'VV ', diagNum ,'MR ' \\
376     \> call diagnostics\_add2list( diagNum, \\
377     \> I diagName, diagCode, diagUnits, diagTitle, myThid ) \\
378     \\
379     \end{tabbing}
380    
381     \input{part7/diagnostics-menu.tex}
382    
383     \newpage
384     \noindent For a list of the diagnostic fields available in the
385     different MITgcm packages, follow the link to the diagnostics menu
386     in the manual section describing the package:
387    
388     \filelink{part6/fizhi-diagnostics-menu.tex}{pkg-fizhi-fizhi-diagnostics-menu.tex}
389    
390     \subsubsection{Dos and Donts}
391    
392     \subsubsection{Diagnostics Reference}
393    

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