[Wrfems] Problem with grib2 winds in AWIPS

Douglas Tilly Douglas.Tilly at noaa.gov
Wed Sep 9 13:23:49 MDT 2009

Bob et al.,

I'm having a problem with AWIPS decoding wind data and I'm wondering if 
it's related to the issue mentioned below.  Our AWIPS is decoding the 
grib2 files and storing everything except for wind data (as far as I can 
tell anyway).  I dug through the grib2 decoder log on dx3 and found 
where it's storing data for uW, but there's no mention of vW...not even 
a mention of it not being decoded. 

I double checked the post_utils.pm file and couldn't find the -nv flag 
under the grib12 subroutine.  So, I added this flag to check and I'm 
still having the same problem. 

The grib2 files mention both UGRD and VGRD, so it appears this is 
working fine.  Why would it it be in the grib2 file, but not show up in 
AWIPS?  Any thoughts? 


Robert Rozumalski wrote:
> Matt,
> Added the "-nv" flag to the beta 2 release, the announcement for which 
> wil be later today.
> Bob
> Matt Foster wrote:
>> Thanks Rich,
>> I just discovered the -nv switch myself.  That looks like something 
>> that either needs to be a default switch or set by an option in 
>> post_grib.conf.
>> Matt @ OUN
>> Richard Grumm wrote:
>>> Matt,
>>> We ran into this to with GEFS downscaled data. Some grib2encoders 
>>> make the winds into a vector so it is one field. AWIPS wants a real 
>>> u and a real v wind grib/grib2 file.
>>> We had to take the files and make them grib1 and then use the -nv 
>>> switch to make sure the grib2 files had real u and v not a vector. 
>>> Grib2 is a good space saver.
>>> This could be the problem.
>>> Rich
>>> Matt Foster said the following on 3/13/2009 9:49 AM:
>>>> I switched my WRF ingest on AWIPS yesterday from GRIB1 to GRIB2, 
>>>> however, the GRIB2 decoder on AWIPS is only extracting the 
>>>> u-component of the winds.  I have a recollection of something like 
>>>> this before, and I believe the solution in that case was to convert 
>>>> from GRIB2 to GRIB1.  I don't really want to do that in this case, 
>>>> as it would defeat the purpose of switching to GRIB2.
>>>> Any suggestions?
>>>> Matt @ OUN
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