EMPTY plots when entire domain values = ZERO

[Kevin M Levey]

WED 12SEP07: 1525PDT

Hi All.

I've come across a problem that I am a little stumped on and it's the first
time I've encountered this error.

I am plotting GFS (1x1 degree) convective cloud values and if I plot the
entire dataset, the plot comes out fine with convective cloud showing up.
However, if I choose a smaller domain where ALL grid points are 0, I expect
GRADS to plot the zero value, however, instead I get a blank plot. Has
anyone ever come across this problem before?

Running GRADSC from the command line gives me the following output:

ga-> test
No hardcopy metafile open
All files closed; all defined objects released
All GrADS attributes have been reinitialized
Cannot plot color bar: No shading information


If I make the domain larger where there is at least one grid box with a
value > 0 then the plot comes out OK.

A copy of the test script:

'reinit'
'set mpdset hires'
'set mpt * off'
'set mpt 0 0 1 6'
'set mpt 1 0 1 1'
'set grads off'
'set timelab on'
'set display color white'
'clear'
'open /prod/custom/Input/modelplots/GFS/temp/gfs_102.ctl'
'clear'
'set xsize 800 600'
'set display color white'
'set lat -36 -16'
'set lon 10 36'
'set map auto 1 1 6'
'define cc = TCDCcvl'

'run /prod/custom/Input/modelplots/GFS/scripts/rgbset_cloud2.gs'
'set gxout shaded'
'set csmooth on'
'd cc'

'run /prod/custom/Input/modelplots/GFS/scripts/SA_cities_clouds.gs'
'run /prod/custom/Input/modelplots/GFS/scripts/cbarn'
'draw title  CONVECTIVE CLOUD COVER (%) \INIT: 12UTC 12SEP07
VALID: 20H00 SUN 16 SEP 2007'

The above domain for this hour has ALL grid points over South Africa = ZERO,
but grads wont plot anything. The forecast hour before and after where at
least one gridpoint has a value  > 0 then the plots came out just fine, and
it only happens when ALL grid points for the domain are ZERO.

Any help would be appreciated indeed.

Thanks.

GRADS information:

Built Mon May 23 13:17:11 EDT 2005 for i686-pc-linux-gnu

This version of GrADS has been configured with the following options:

   o This is a 32-bit LITTLE ENDIAN machine version.
   o Command line editing (readline) ENABLED.
   o CIRES/CDC (http://www.cdc.noaa.gov) SDF/XDF interface DISABLED.
     This version is NOT configured to read NetCDF/HDF-SDS files.
   o DTYPE netcdf and DTYPE hdfsds are DISABLED.
   o OPeNDAP (a.k.a. DODS) gridded data interface DISABLED.
   o OPeNDAP (a.k.a. DODS) station data interface DISABLED.
   o PCMDI (http://www-pcmdi.llnl.gov) LATS interface ENABLED.
     This version is configured to write GRIB files (but no NetCDF/HDF
files).
   o DAO (http://dao.gsfc.nasa.gov) Athena Widget GUI DISABLED.
   o NRL/DAO/PCMDI XA or ImageMagick Image Output DISABLED.
   o printim command for direct png/gif output ENABLED.
     (via the GD Library -- http://www.boutell.com/gd)

Regards

Kevin M Levey, MSc (University of Cape Town)
Director of Meteorological Operations
CustomWeather, Inc
San Francisco, CA, USA

http://www.1stweather.com
http://www.myforecast.com
http://www.customweather.com