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20020108: handling MIXR with grid diagnostics in gempak
- Subject: 20020108: handling MIXR with grid diagnostics in gempak
- Date: Tue, 08 Jan 2002 10:44:20 -0700
Clint,
This is the quick answer...
You are right in that the display of MIXR is scaled by 1000 to
produce g/kg (see $GEMPAK/source/gemlib/dg/dgscal.f). Calculations
are done in the dimensionless MKS units.
However, once you perform a calculation on the data (in MKS units),
and store the output for a different name (other than the recognized MIXR
name), your display will not be scaled to g/kg. So, you will have to
take that into acount when you SCALE the output for display.
I believe that is the gist of your message below. That is, when you
specify GRDNAM as MIXR_MOD for copying the data, the display output
will not be scaled to g/kg as MIXR would. You may also notice some
small roundoff changes due to the packing (PACK=grib/16) if the original
data used more precision.
If you want me to look into a specific calculation and how
to carry forth the MKS units let me know.
Chiz
Steve Chiswell
Unidata User Support
>From: Clint Rowe <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200201081709.g08H91N04033
>Chiz,
>
>I'm finding some strange behavior when trying to do some grid computations
>in gempak. I'm trying to compare two MM5 model runs and am creating a three-
>panel display (the two fields and their difference) using version 5.6e. I've
>written a script that does this for whatever field I'm interested in.
>Everything seemed to be working okay until Mark noticed that when plotting
>2m mixing ratios, the difference map were all blank, even though there are
>noticable differences in the two model runs. If I run GDLIST on the two
>files and look at mixr, mixr+2 and sub(mixr, mixr+2), I get strange results.
>The reported mins and maxs look okay for the two runs and show differences
>as seen in the plots. However, the results of the subtraction seems to
>yield zeros across the entire domain (i.e., the min and max are both zero).
>
>
>papagayo% gdlist
> GDATTIM Grid date/time 860731/1200
> GLEVEL Grid level 2
> GVCORD Grid vertical coordinate zagl
> GFUNC Scalar grid mixrdiff
> GDFILE Grid file test.gem
> GAREA Graphics area dset
> PROJ Map projection/angles/margins|dr MER
> SCALE Scalar scale / vector scale 0
> OUTPUT Output device/filename T
> Parameters requested: GDATTIM,GLEVEL,GVCORD,GFUNC,GDFILE,GAREA,PROJ,SCALE,
> OUTPUT.
>
>GEMPAK-GDLIST>gdfil=../CTL/1986073100/1986073100_mm5_domain3.gem+../MOD/198607
> 31
>00/1986073100_mm5_domain3.gem
> GEMPAK-GDLIST>gfunc=mixr
> GEMPAK-GDLIST>r
>
>
> GDLIST PARAMETERS:
>
> Grid file:
>../CTL/1986073100/1986073100_mm5_domain3.gem+../MOD/1986073100/1986073100_mm5_
> do
>main3.gem
> GRID IDENTIFIER:
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL MIXR
>
> GAREA: dset
> SCALE FACTOR : 10** 0
> OUTPUT: TERM/
>
> MINIMUM AND MAXIMUM VALUES 5.58 13.44
>Enter <cr> to accept parameters or type EXIT:ex
> Parameters requested: GDATTIM,GLEVEL,GVCORD,GFUNC,GDFILE,GAREA,PROJ,SCALE,
> OUTPUT.
> GEMPAK-GDLIST>gfun=mixr+2
> GEMPAK-GDLIST>r
>
>
> GDLIST PARAMETERS:
>
> Grid file:
>../CTL/1986073100/1986073100_mm5_domain3.gem+../MOD/1986073100/1986073100_mm5_
> do
>main3.gem
> GRID IDENTIFIER:
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL MIXR
>
> GAREA: dset
> SCALE FACTOR : 10** 0
> OUTPUT: TERM/
>
> MINIMUM AND MAXIMUM VALUES 5.52 13.43
>Enter <cr> to accept parameters or type EXIT:ex
> Parameters requested: GDATTIM,GLEVEL,GVCORD,GFUNC,GDFILE,GAREA,PROJ,SCALE,
> OUTPUT.
> GEMPAK-GDLIST>gfun=sub(mixr,mixr+2)
> GEMPAK-GDLIST>r
>
>
> GDLIST PARAMETERS:
>
> Grid file:
>../CTL/1986073100/1986073100_mm5_domain3.gem+../MOD/1986073100/1986073100_mm5_
> do
>main3.gem
> GRID IDENTIFIER:
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL SUBMIXR
>
> GAREA: dset
> SCALE FACTOR : 10** 0
> OUTPUT: TERM/
>
> MINIMUM AND MAXIMUM VALUES 0.00 0.00
>Enter <cr> to accept parameters or type EXIT:ex
> Parameters requested: GDATTIM,GLEVEL,GVCORD,GFUNC,GDFILE,GAREA,PROJ,SCALE,
> OUTPUT.
> GEMPAK-GDLIST>ex
>papagayo%
>
>
>Okay, so if that wasn't a big enough problem, when I started putting together
>something to send you, I found even more strangeness. I copied the mixing
>ratio fields from the two files into a new file that I could send to you. I
>also calculated the deifference to add to that file. Then, when I began to
>check my efforts, I found that the grids I had copied were different than
>what I expected. The raw fields had been multipled by 1000 and now there are
>small differences (but smaller than implied by the fields themselves).
>
>
>papagayo% gdcfil
> GDOUTF Output grid file test.gem
> PROJ Map projection/angles/margins|dr MER
> GRDAREA Area covered by grid
> KXKY Number of grid points in x;y 10;10
> MAXGRD Maximum number of grids 200
> CPYFIL Grid file whose navigation is to
>../CTL/1986073100/1986073100_mm5_domain3.gem
> ANLYSS Grid analysis block 4/2;2;2;2
> Parameters requested: GDOUTF,PROJ,GRDAREA,KXKY,MAXGRD,CPYFIL,ANLYSS.
> GEMPAK-GDCFIL>r
>
> GDCFIL PARAMETERS:
>
> New grid file: test.gem
>
> File copied: ../CTL/1986073100/1986073100_mm5_domain3.gem
>
> Grid projection: LCC
> Lower left corner: 40.51 -104.66
> Upper right corner: 43.65 -96.77
> KX, KY: 156 90
> DELTAN = 4.000 EXTEND = 2; 2; 2; 2
> Maximum number of grids that can be added to file 200
>Enter <cr> to accept parameters or type EXIT:
> Parameters requested: GDOUTF,PROJ,GRDAREA,KXKY,MAXGRD,CPYFIL,ANLYSS.
> GEMPAK-GDCFIL>ex
>papagayo% gddiag
> GDFILE Grid file
>../CTL/1986073100/1986073100_mm5_domain3.gem+../MOD/1986073100/1986073100_mm5_
> do
>main3.gem
> GDOUTF Output grid file test.gem
> GFUNC Scalar grid sub(mixr,mixr+2)
> GDATTIM Grid date/time 860731/1200
> GLEVEL Grid level 2
> GVCORD Grid vertical coordinate zagl
> GRDNAM Grid parameter name mixr_mod
> GPACK Packing type/number of bits grib/16
> Parameters requested: GDFILE,GDOUTF,GFUNC,GDATTIM,GLEVEL,GVCORD,GRDNAM,
> GPACK.
> GEMPAK-GDDIAG>gfunc=mixr+2
> GEMPAK-GDDIAG>r
>
>
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL MIXR_MOD
>Enter a new grid parameter name, <cr> to accept or type EXIT:
> Parameters requested: GDFILE,GDOUTF,GFUNC,GDATTIM,GLEVEL,GVCORD,GRDNAM,
> GPACK.
> GEMPAK-GDDIAG>gfunc=mixr
> GEMPAK-GDDIAG>grdnam=mixr_ctl
> GEMPAK-GDDIAG>r
>
>
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL MIXR_CTL
>Enter a new grid parameter name, <cr> to accept or type EXIT:
> Parameters requested: GDFILE,GDOUTF,GFUNC,GDATTIM,GLEVEL,GVCORD,GRDNAM,
> GPACK.
> GEMPAK-GDDIAG>l
> GDFILE =
>../CTL/1986073100/1986073100_mm5_domain3.gem+../MOD/1986073100/1986073100_mm5_
> do
>main3.gem
> GDOUTF = test.gem
> GFUNC = mixr
> GDATTIM = 860731/1200
> GLEVEL = 2
> GVCORD = zagl
> GRDNAM = mixr_ctl
> GPACK = none
> GEMPAK-GDDIAG>gfunc=sub(mixr,mixr+2)
> GEMPAK-GDDIAG>l
> GDFILE =
>../CTL/1986073100/1986073100_mm5_domain3.gem+../MOD/1986073100/1986073100_mm5_
> do
>main3.gem
> GDOUTF = test.gem
> GFUNC = sub(mixr,mixr+2)
> GDATTIM = 860731/1200
> GLEVEL = 2
> GVCORD = zagl
> GRDNAM = mixr_ctl
> GPACK = none
> GEMPAK-GDDIAG>grdnam=mixrdiff
> GEMPAK-GDDIAG>r
>
>
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL MIXRDIFF
>Enter a new grid parameter name, <cr> to accept or type EXIT:
> Parameters requested: GDFILE,GDOUTF,GFUNC,GDATTIM,GLEVEL,GVCORD,GRDNAM,
> GPACK.
> GEMPAK-GDDIAG>ex
>papagayo%
>papagayo% gdinfo
> GDFILE Grid file
>../CTL/1986073100/1986073100_mm5_domain3.gem+../MOD/1986073100/1986073100_mm5_
> do
>main3.gem
> LSTALL Full list flag YES
> OUTPUT Output device/filename T
> GDATTIM Grid date/time 860731/1200
> GLEVEL Grid level 2
> GVCORD Grid vertical coordinate zagl
> GFUNC Scalar grid sub(mixr,mixr+2)
> Parameters requested: GDFILE,LSTALL,OUTPUT,GDATTIM,GLEVEL,GVCORD,GFUNC.
> GEMPAK-GDINFO>gdfil=test.gem
> GEMPAK-GDINFO>gfunc=all
> GEMPAK-GDINFO>r
>
> GRID FILE: test.gem
>
>
> GRID NAVIGATION:
> PROJECTION: LCC
> ANGLES: 30.0 -103.0 60.0
> GRID SIZE: 156 90
> LL CORNER: 40.51 -104.66
> UR CORNER: 43.65 -96.77
>
> GRID ANALYSIS BLOCK:
> ANALYSIS TYPE: BARNES
> DELTAN: 4.000
> DELTAX: -9999.000
> DELTAY: -9999.000
> GRID AREA: 39.00 -106.00 45.00 -96.00
> EXTEND AREA: 39.00 -106.00 45.00 -96.00
> DATA AREA: 39.00 -106.00 45.00 -96.00
>
> Number of grids in file: 3
>
> Maximum number of grids in file: 200
>
> NUM TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
> 1 860731/1200 2 ZAGL MIXR_MOD
> 2 860731/1200 2 ZAGL MIXR_CTL
> 3 860731/1200 2 ZAGL MIXRDIFF
> Parameters requested: GDFILE,LSTALL,OUTPUT,GDATTIM,GLEVEL,GVCORD,GFUNC.
> GEMPAK-GDINFO>ex
>papagayo% gdlist
> GDATTIM Grid date/time 860731/1200
> GLEVEL Grid level 2
> GVCORD Grid vertical coordinate zagl
> GFUNC Scalar grid all
> GDFILE Grid file test.gem
> GAREA Graphics area dset
> PROJ Map projection/angles/margins|dr MER
> SCALE Scalar scale / vector scale 999
> OUTPUT Output device/filename T
> Parameters requested: GDATTIM,GLEVEL,GVCORD,GFUNC,GDFILE,GAREA,PROJ,SCALE,
> OUTPUT.
> GEMPAK-GDLIST>gfun=mixr_ctl
> GEMPAK-GDLIST>scal=0
> GEMPAK-GDLIST>r
>
>
> GDLIST PARAMETERS:
>
> Grid file: test.gem
>
> GRID IDENTIFIER:
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL MIXR_CTL
>
> GAREA: dset
> SCALE FACTOR : 10** 0
> OUTPUT: TERM/
>
> MINIMUM AND MAXIMUM VALUES 5578.01 13438.01
>Enter <cr> to accept parameters or type EXIT:ex
> Parameters requested: GDATTIM,GLEVEL,GVCORD,GFUNC,GDFILE,GAREA,PROJ,SCALE,
> OUTPUT.
> GEMPAK-GDLIST>gfunc=mixr_mod
> GEMPAK-GDLIST>r
>
>
> GDLIST PARAMETERS:
>
> Grid file: test.gem
>
> GRID IDENTIFIER:
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL MIXR_MOD
>
> GAREA: dset
> SCALE FACTOR : 10** 0
> OUTPUT: TERM/
>
> MINIMUM AND MAXIMUM VALUES 5519.52 13429.52
>Enter <cr> to accept parameters or type EXIT:ex
> Parameters requested: GDATTIM,GLEVEL,GVCORD,GFUNC,GDFILE,GAREA,PROJ,SCALE,
> OUTPUT.
> GEMPAK-GDLIST>gfunc=mixrdiff
> GEMPAK-GDLIST>r
>
>
> GDLIST PARAMETERS:
>
> Grid file: test.gem
>
> GRID IDENTIFIER:
> TIME1 TIME2 LEVL1 LEVL2 VCORD PARM
>860731/1200 2 ZAGL MIXRDIFF
>
> GAREA: dset
> SCALE FACTOR : 10** 0
> OUTPUT: TERM/
>
> MINIMUM AND MAXIMUM VALUES -0.55 0.95
>Enter <cr> to accept parameters or type EXIT:ex
> Parameters requested: GDATTIM,GLEVEL,GVCORD,GFUNC,GDFILE,GAREA,PROJ,SCALE,
> OUTPUT.
> GEMPAK-GDLIST>ex
>papagayo%
>
>
>
>Can you explain what's happening?
>
>Clint
>
>
>
>====================================================================
>Clinton M. Rowe
>Associate Professor
>Meteorology/Climatology Program phone:(402)472-1946
>Department of Geosciences fax:(402)472-4917
>University of Nebraska-Lincoln address@hidden
>
>