[Cosmic_announce] (no subject)

[Sean Healy]

Dear Doug,

I agree with Lidia. I cannot look at/test the data in two weeks.
It will considerably longer than that to run an experiment
with the Nov/Dec data.


Many thanks,

Sean.





On Fri, March 20, 2009 6:13 pm, Lidia Cucurull wrote:
> Dear Doug,
>
>
> Please, do NOT make any change in the operational data stream until
> the operational weather services have time to test the impact of the
> changes. I believe it will take more than a couple of weeks.
>
> Thanks
> Lidia
>
>
> On Mar 20, 2009, at 1:36 PM, Doug Hunt wrote:
>
>
>> Greetings:
>>
>>
>> Recently it was found (thanks to Christian Marquardt from EUMETSAT)
>> that the filtering used in our inversion software produces a bias in
>> retrieved bending angles. This bias is seen mainly above 10-20km and its
>> magnitude is of order of 0.1-0.2%. This bias is due to second derivative
>> of the excess phase as a function of time. This bias propagates into the
>> retrieved refractivity and, subsequently, into other retrieved profiles.
>> We will be replacing the filtering which
>> reduces the bias by several decimal orders of magnitude.
>>
>> Concurrently we will be making another change by fixing the transition
>> height between geometric optics and radio holographic processings to ~20
>> km (currently this height is determined individually for each
>> occultation and can be anywhere between ~10 and ~20 km). The purpose of
>> this change is to aid studies of the structure of tropopause by
>> providing the vertical resolution of about ~0.1 km below 20 km for all
>> occultations.
>>
>> Both these changes are not yet included in our real time processing.
>> The data, BUFR files for November-December 2008, processed with
>> these changes are available at:
>>
>> http://www.cosmic.ucar.edu/~dhunt/BUFR_with_new_filtering/
>>
>>
>> for testing in data assimilation systems. We would appreciate your
>> feedback. We would like to include these changes in our real time
>> processing in about 2 weeks. Later, we will re-process all our data for
>> all missions.
>>
>> Best Regards,
>>
>>
>> Doug Hunt
>>
>>
>> dhunt at ucar.edu Software Engineer IV
>> UCAR - COSMIC, Tel. (303) 497-2611
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