[Cosmic_announce] Edition 4 BUFR files expected soon!

Wed Nov 21 11:32:24 MST 2012

Doug,

I ran a comparison of the COSMIC data file.  I don't appear to be receiving CNOFS data.  I used to, but it has stopped for some reason.  I ran a processing of the data, and I output the files in the NCAR WRF Little_r format for assimilation into the WRF3DVAR.  Like Josep, I am seeing differences.  All fields in the data file show differences.  I will provide a copy of the data file from the current production and the test file to you in a separate email.  Since I can't tell the impact of the differences, I am concerned about the change.  I request a delay until this can be addressed.  I will be leaving for the weekend later today, so I won't be able to run any more tests until next week.  

Please let me know if you have questions.  I'm sending the data file and the code to that describes how the file is formatted shortly.  Thank you.

Richard Ritz

/signed/
RICHARD L. RITZ, GS-12, 16WS/WXN
Meteorologist, Data Assimilation Team and Specialized Models Team
Commercial:  (402) 294-3918
DSN:  271-3918

-----Original Message-----
From: cosmic_announce-bounces at ucar.edu [mailto:cosmic_announce-bounces at ucar.edu] On Behalf Of Doug Hunt
Sent: Wednesday, November 21, 2012 11:49 AM
To: Josep Aparicio
Cc: Announcements about the COSMIC mission
Subject: Re: [Cosmic_announce] Edition 4 BUFR files expected soon!

Hi Josep:  What are you comparing with?  When I compared the v4 vs. the 
old v3 BUFR files I only noticed a handful of values different in the last 
decimal place, consistent with a rounding error.

Could you give me more information on the comparison you did?

Thanks,

   Doug

dhunt at ucar.edu
Software Engineer
UCAR - COSMIC, Tel. (303) 497-2611

On Wed, 21 Nov 2012, Josep Aparicio wrote:

> Doug,
>
> I doubt the differences are only single/double precision.
> All impact parameters are shifted by a constant -3m in the new version,
> -2.5m in some levels. I would expect single vs double precision to produce
> a random jitter.
>
> Bending angles look compatible between versions, though, as they are larger
> in the new version by a factor of ~(1+1/2000), which is compatible with the
> 3m systematic shift and the atmospheric vertical scale height of ~6.5 km.
> 3m/6.5km ~ 1/2000
>
> However, the entire thing looks puzzling, as if something else, beyond the
> BUFR edition was changed, and probably upstream of the BUFR encoding.
>
> Josep
>
> On 11/21/12 11:41, Doug Hunt wrote:
>> Hi Harald:  I did notice a few small differences in the data values.
>> These are due to the fact that I am using a different BUFR library that
>> uses double precision rather than single precision.  So, if anything the
>> new values ought to be more accurate.
>> 
>> As to the 175 'originating center' value, we have contacted NOAA to apply
>> to the WMO about getting 175 reserved for 'UCAR' rather than using 60
>> ('NCAR').
>> 
>> Regards,
>>
>>     Doug
>> 
>> dhunt at ucar.edu
>> Software Engineer
>> UCAR - COSMIC, Tel. (303) 497-2611
>> 
>> On Wed, 21 Nov 2012, Harald Anlauf wrote:
>> 
>>> Hi Doug!
>>> 
>>> On Tuesday, 20. November 2012 21:06:28 Doug Hunt wrote:
>>>> Greetings:
>>>> 
>>>> The current version of BUFR files available from CDAAC and the
>>>> GTS is edition 3.  By the end of November, the WMO wants all edition 3
>>>> files to be phased out in favor of the more recent edition 4 BUFR files.
>>>> 
>>>> The change is only a small difference in the header--all the values
>>>> remain the same.  Attached are sample edition 4 BUFR files from the 
>>>> COSMIC
>>>> and C/NOFS missions.
>>> the attached data actually do show small differences to the data
>>> disseminated via GTS (usually a few meters in impact parameter, and
>>> also small differences in the bending angles), but the obs-model check
>>> shows that the effective differences are much smaller than the
>>> observation errors we apply operationally.
>>> 
>>> While running these data through our assimilation system, I noticed
>>> that the field "originating center" is set to 175 (i.e. reserved for
>>> other centers).  Is there a reason that you do not use the value 60
>>> there, or is it an oversight?
>>> 
>>>> Next week we plan to start delivering these files.  Note that the version
>>>> will change from the current '0001.0006' to '0001.0007'.
>>>> 
>>>> Please let me (dhunt at ucar.edu) know if you see a problem with these
>>>> files or need extra time!
>>> Cheers,
>>> Harald
>>> 
>>> -- 
>>> Dr. Harald Anlauf
>>> Deutscher Wetterdienst (DWD)           | Phone:  +49 69 8062 4941
>>> FE12 / Datenassimilation               | Fax:    +49 69 8062 3721
>>> Frankfurter Str. 135                   | e-Mail: harald.anlauf at dwd.de
>>> 63067 Offenbach                        | Web:    http://www.dwd.de
>>> 
>> _______________________________________________
>> Cosmic_announce mailing list
>> Cosmic_announce at ucar.edu
>> http://mailman.ucar.edu/mailman/listinfo/cosmic_announce
>> 
>
> -- 
> Dr. Josep Maria APARICIO
> Data Assimilation and Satellite Meteorology
> Environment Canada
> 2121 Transcanada
> H9P 1J3 Dorval, QC, Canada
>
> Tel: (+1)-514-421-4687
> Fax: (+1)-514-421-2106
> Josep.Aparicio at ec.gc.ca
>
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