[Cosmic_announce] Edition 4 BUFR files expected soon!

[Doug Hunt]

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
>>> 
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>> 
>
> -- 
> 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
>