[gradsusr] Problem extracting HIRLAM gribfile

Thu Mar 17 08:17:59 EDT 2011

Hello,

thank you for your help again! I have tried to use other packing
options, but somehow I still get stuck. For example, I converted the
original file to grib2 format with other packing options using the
following commands from the ECMWF tools:
./grib_set -s edition=2 test.grib out.grib2
./grib_set -s packingType=grid_simple out.grib2 out_simple.grib2

When using g2ctl afterwards, I still get the negative sign in the
control file. When I manually change this to a positive value, I can
successfully create an index file using gribmap.

However, when I then try to use the grib file in GrADS, I get strange
lat and lon fields which might be related to the g2ctl problem:
Data file out_simple.grib2 is open as file 1
LON set to 245.438 406.305
LAT set to 7.2 51.36
LEV set to 1 1
Time values set: 2011:3:12:0 2011:3:12:0

When I try to plot data from this file, I still get "Cannot contour
grid - all undefined values":
ga-> set lon 0 360
LON set to 0 360
ga-> set lat 0 90
LAT set to 0 90
ga-> d tmp2m
Notice:  Automatic Grid Interpolation Taking Place
Cannot contour grid - all undefined values

Is this a problem in the conversion or in the g2ctl code? How can I fix this?

Again, thank you for your help!

Best regards,
Jonas Kaufmann

On Tue, Mar 15, 2011 at 17:39, Wesley Ebisuzaki
<Wesley.Ebisuzaki at noaa.gov> wrote:
> Hi,
>
>  5.50002 is a locally defined table.  This compression has been defined
> by the ECMWF and I
> haven't seen any documentation describing it.  When you convert from
> grib1, try using a
> standard packing method rather than a locally defined one (0/2/3/40).  I
> think that I broke
> the rotated lat-lon support in g2ctl.  Hard to fix with out some good
> sample files.
>
>        Wesley
>
> Jennifer Adams wrote:
>> You've got another problem with this grib file. That error message
>> "getdrstemplate: DRS..." is from the grib2 library, not GrADS. Data
>> Representation Template 5.50002 is not in my GRIB2 doc, nor is it in a
>> newer version of the doc from WMO.
>> --Jennifer
>>
>> On Mar 15, 2011, at 11:24 AM, Jonas Kaufmann wrote:
>>
>>> Hello Jennifer,
>>>
>>> thank you! This was the output that was generated by g2ctl.pl
>>> (including the negative sign), so I think the error is on the
>>> g2ctl-side.
>>>
>>> However, when I manually change this to a positive value, I get
>>> another error:
>>> grib2map: scanning GRIB2 file: out.grib2
>>> getdrstemplate: DRS Template 5.50002 not defined.
>>> grib2map error: g2_getfld failed: ierr=12
>>>
>>> Is this a related problem or am I running into another problem with
>>> the grib file?
>>>
>>> Best regards,
>>> Jonas Kaufmann
>>>
>>> On Tue, Mar 15, 2011 at 15:14, Jennifer Adams <jma at cola.iges.org
>>> <mailto:jma at cola.iges.org>> wrote:
>>>>
>>>> On Mar 15, 2011, at 10:05 AM, Jonas Kaufmann wrote:
>>>>
>>>> Hello Wesley,
>>>>
>>>> thank you for your help! I could convert the file to grib2 using ECMWF
>>>> grib_set, see the converted file as an attachment. I then used the
>>>> latest versions of g2ctl and wgrib2 to create a control file (also
>>>> attached). During this process I get the following error):
>>>> Argument "0.000000:winds(grid)" isn't numeric in multiplication (*) at
>>>> /usr/share/perl/5.10/Math/Trig.pm line 87.
>>>>
>>>> Now when I try to create an index file for the grib2-file, gribmap
>>>> complains with this error:
>>>> Open Error:  Missing or invalid dimension increment value
>>>>  --> The invalid description file record is:
>>>>  --> xdef 351 linear 245.437796901893 -0.459621342512909
>>>>  The data file was not opened.
>>>>
>>>> Not sure what the 1st problem mentioned above means, but this message is
>>>> telling you that XDEF cannot have a negative increment value. You
>>>> must start
>>>> with the minimum longitude and have positive increment.
>>>> --Jennifer
>>>>
>>>> Is there a simple (manual?) way to fix this in the control file? Or is
>>>> there another option on how to display data from this file?
>>>>
>>>> Thank you for your help!
>>>>
>>>>
>>>> Best regards,
>>>> Jonas Kaufmann
>>>>
>>>> On Fri, Mar 11, 2011 at 20:08, Wesley Ebisuzaki
>>>> <Wesley.Ebisuzaki at noaa.gov <mailto:Wesley.Ebisuzaki at noaa.gov>> wrote:
>>>>
>>>> Jonas,
>>>>
>>>>   Your grib1 file is packed using "complex packing".  This kind of
>>>>
>>>> packing is
>>>>
>>>> not supported by grib2ctl and GrADS.
>>>>
>>>>   I think that you are getting the error message because the grid is
>>>>
>>>> (582 x 424) or 246768 points.
>>>>
>>>> However, the number of grid points (could be modified by undefineds and
>>>>
>>>> runs of identical values)
>>>>
>>>> is given by octets 19-20 in section 4. Since 246768 much too big to be
>>>>
>>>> stored in a 2 byte number,
>>>>
>>>> an error is flagged.  Try converting this file to grib2 using the ECMWF
>>>>
>>>> software.  Once in grib2,
>>>>
>>>> g2ctl and GrADS can read it.  I don't think that g2ctl will handle the
>>>>
>>>> projection right but at least you
>>>>
>>>> can display it as a x-y grid.
>>>>
>>>> http://www.nco.ncep.noaa.gov/pmb/docs/on388/section4.html
>>>>
>>>>
>>>>    Wesley Ebisuzaki
>>>>
>>>> Jonas Kaufmann wrote:
>>>>
>>>> Hello,
>>>>
>>>> I ran into a problem trying to extract a HIRLAM data set on a rotated
>>>>
>>>> lat-lon grid. the file is in grib1-format. I could create a valid
>>>>
>>>> control file using the code from g2ctl.pl for grib2-files, merging
>>>>
>>>> this together with the code in grib2ctl.pl for grib1 files. Although a
>>>>
>>>> control file is created, I also get errors like:
>>>>
>>>> grib header at record 1: two values of nxny 246768 144639
>>>>
>>>>    LEN 162734 DataStart 14 UnusedBits 6 #Bits 9 nxny 246768
>>>>
>>>> When I then go ahead and try to plot a map using GrADS, I always get
>>>>
>>>> "Entire Grid undefined". I have attached the grib file, the index file
>>>>
>>>> and the control file.
>>>>
>>>> What am I doing wrong? How can I extract the data from this gribfile?
>>>>
>>>> Thank you for your help!
>>>>
>>>> Best regards,
>>>>
>>>> Jonas Kaufmann
>>>>
>>>> ------------------------------------------------------------------------
>>>>
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>>>> <out.grib2.ctl><out.grib2>_______________________________________________
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>>>> --
>>>> Jennifer M. Adams
>>>> IGES/COLA
>>>> 4041 Powder Mill Road, Suite 302
>>>> Calverton, MD 20705
>>>> jma at cola.iges.org <mailto:jma at cola.iges.org>
>>>>
>>>>
>>>>
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>>>
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>>
>> --
>> Jennifer M. Adams
>> IGES/COLA
>> 4041 Powder Mill Road, Suite 302
>> Calverton, MD 20705
>> jma at cola.iges.org <mailto:jma at cola.iges.org>
>>
>>
>>
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