[Met_help] MM5 GRIB1 format

John Halley Gotway johnhg at rap.ucar.edu
Thu May 7 09:57:05 MDT 2009


I heard back from the other MET user who is verifying MM5 data.  He's posted the code he's using to convert from MM5 sigma levels to pressure levels and then create a GRIB1 file.  Please see the
details in his message below.

Based on the reason he wrote to MET-Help, it may be the case that there's still some issues to be worked out in the process of writing the GRIB file.  The time values may not be correct in the GRIB
file that's generated.

Hope this helps!



Hello John,

Thank you for contacting me on this issue. In fact, let me give you a
new tar file in which there is one hour of MM5 data with all steps of
converting MM5 sigma levels to pressure, then into grib1 files, and then
running MET on the output files, including all source code, so other
user can go through the steps after we figure out what to do. I am also
including a README.1st file that I wrote to remember how I did all these
calculations in the future file within compare.with.MET subdirectory
which explains the process step by step. Most important step is
MM5toGRIB routine which was provided by scientists in Spain.

I placed the new tar file to our anonymous site for you to retrieve:


You can get the source code for MM5toGRIB module including many other
utilities from here:


(in the middle of that web page, you will see the link for MM5toGRIB).

You will find compiled MM5toGRIB code in my tar file, as well.

As I was writing this e-mail, I got your next e-mail with your
suggestions to debug the problem. In fact, that is exactly what I
thought. I tried "FULL" in spatial comparisons. And, I checked the time
periods. Only thing that didn't quite make sense is the order of grib1
file based on the help given in README file in MM5toGRIB subdirectory:


It seems like the order of parameters (particularly the date) written in
grib1 file is not correct, based on the above link. I am still trying to
debug it.

Thank you very much for helping me on this issue. I will still follow
your suggestions one more time to find the problem.


C.V.Srinivas wrote:
> Dear John Halley,
> Thank you for your response. I will be happy to receive useful
> information regarding conversion of MM5 outputs for GRIB  format
> required by MET2.
> I came across an article from  zielonka at meteo.psu.edu,
> hunter at meteo.psu.edu "WRF AND MM5 REALTIME SYSTEM STATISTICAL
> presentation. They developed a conversion program GRIBPRS for MM5
> outputs for using in MET . I asked their help to provide their code for
> my purpose. But I did not get reply from them. Can you please write to
> them and get me the GRIBPRS code for using the MET2.0 in my research
> project?
> With regards
> C.V.Srinivas
> John Halley Gotway wrote:
>> Hello,
>> Unfortunately, I'm not familiar enough with MM5 data formats to offer any
>> suggestions on how you might go about converting your MM5 data into a
>> format for use with MET.  We primarily deal with WRF data at the
>> Developmental Testbed Center (DTC).
>> However, by coincidence, on the same day we received your MET-Help
>> request, we received a help request from a different user who is using
>> MM5
>> data.  He was able to convert it from sigma levels to pressure levels and
>> write out GRIB verison 1 files for use with MET.  I've written him to ask
>> for details on how he went about it.
>> I'll pass along any information or advice I hear from him to you.
>> Thanks,
>> John Halley Gotway
>> johnhg at ucar.edu
>>> Dear Sir,
>>> We have downloaded the METv2.0 software and installed. Our aim is to use
>>> this package for the model evaluation of MM5 model over the India
>>> region. However the MM5 files cannot be directly read by METv2.0 and
>>> needs to be converted in GRIB format. Are there tools developed for
>>> conversion of MM5 files to the compatible grib format required by
>>> METv2.0. Please advise
>>> thanks and regards
>>> C.V.Srinivas
>>> Scientist E
>>> Radiological Safety Divison
>>> Kalpakkam , India
>>> _______________________________________________
>>> Met_help mailing list
>>> Met_help at mailman.ucar.edu
>>> http://mailman.ucar.edu/mailman/listinfo/met_help

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