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19990831: displaying grid files

Chris,

To convert a plain text file into a gempak gridded file, your ascii
file would need to be in the format that "gdlist" outputs. Then,
you would runn the "gdedit" program to import the grid into the
gempak file you created with "gdcfil".

However,
In the Gempak distribution, I have a program called dcreanal which
will convert NCEP reanalysis files from NetCDF to Gempak format
which may be a much easier process provided your grid is a standard
CED grid and not a gaussian grid.

To build dcreanal you need the NetCDF library installed- presumably you
already have this if you have dumped out the data previously.
Edit the $NAWIPS/config/Makeinc.common file and define the NETCDFINC
and NETCDF variables to point to your netcdf include and library file
respectively. Then build dcreanal with:

cd $NAWIPS/unidata/ldmbridge/dcreanal
make clean
make all
make install
make clean

The dcreanal program isn't built by default since it relies on you having
already installed the NetCDF library.

To run dcreanal,

dcreanal netcdffile gemfile_YYYYMM.gem

Use the YYYYMM template in the gempak output file name to get monthly
output gempak files (since the reanalysis files are generally
a year at a time and Gempak can only hold 200 times in a single file).

Steve Chiswell
Unidata User Support


On Tue, 31 Aug 1999, Chris Hennon wrote:

> Steve -
> 
> I'm a little bit foggy here.  I want to display some of the fields from
> the NCEP Reanalysis data I have here.  I parsed out the level and variable
> that I want to display.  The output file is plain text, one value to a
> line, in the standard NCEP convention with the first point corresponding
> to 90N, 0E.  
> 
> Now, I created a grid file using GDCFIL, which looks like this:
> 
>  GEMPAK-GDINFO>r
> 
>  GRID FILE: /home/chennon/gempak/grids/ncep_reanal.grd                        
>       
> 
>  GRID NAVIGATION: 
>      PROJECTION:          CED                 
>      GRID SIZE:           42  19
>      LL CORNER:               0.00   -100.00
>      UR CORNER:              50.00      0.00
> 
>  GRID ANALYSIS BLOCK: 
>      ANALYSIS TYPE:        BARNES
>      DELTAN:               5.228
>      DELTAX:           -9999.000
>      DELTAY:           -9999.000
>      GRID AREA:            -1.00 -101.00   51.00    1.00
>      EXTEND AREA:          -7.00 -106.00   57.00    6.00
>      DATA AREA:            -7.00 -106.00   57.00    6.00
> 
>  Number of grids in file:     0
> 
>  Maximum number of grids in file:    200
> 
>  Parameters requested: GDFILE,LSTALL,OUTPUT.
> 
> 
> My grid size is only 42 x 19 because I'm only interested in displaying the
> tropical Atlantic basin.  My question is, do I HAVE to make this grid in
> order to display my data in GEMPAK?  If so, which program do I use to
> actually run the contouring routine?  Obviously I don't understand the
> steps I need to take.  Thanks for any help.
> 
> Chris 
> 
> 
>