[ldm-users] [conduit] GFS change at 1200 UTC 25 September?

[Kevin R. Tyle]

You can see the noisiness in the attached gif; just a 500 hPa height 
field.  For comparison, a similar plot from last year shows how things 
looked with the old postprocessor.

I suspect the change in the post processor, with the stated 
intention of making the NAM and GFS post processing schemes uniform, has 
eliminated a smoothing process that has heretofore existed with the 0.5 
GFS model output.  The "new" look of this field recalls the "noisiness" 
that we have typically seen with the hi-res NAM output.

Any way to see if the pre-9/25 1200 UTC fields had smoothing built-in to 
the postprocessor?
______________________________________________________________________
Kevin Tyle, Systems Administrator               **********************
Dept. of Earth & Atmospheric Sciences           ktyle at atmos.albany.edu
University at Albany, ES-235                    518-442-4578 (voice)
1400 Washington Avenue                          518-442-5825 (fax)
Albany, NY 12222                                **********************
______________________________________________________________________

On Fri, 28 Sep 2007, David Knight wrote:

> But that notice
>
> http://www.nws.noaa.gov/om/notification/tin07-59gfs_upgrade_unifiedpost.txt
>
> says:
>
> "THE PRIMARY IMPACT TO CUSTOMERS RECEIVING THE GFS WILL BE THAT
> THE DEFAULT PRECIPITATION TYPE ALGORITHM WILL CHANGE"
>
> and further
>
> "THE PRODUCTS/GRIDS WHICH ARE DISSEMINATED TO NOAAPORT AND/OR THE
> SATELLITE BROADCAST NETWORK /SBN/ WILL NOT BE CHANGED IN VOLUME
> OR CONTENT."
>
> So there appears to be more to this than that . . .
>
> David
>
>
> "> Harry,
>>
>> NCEP posted a notice regarding change in the GFS postprocessor
>> coincident
>> with the 12Z Sep 25 run:
>>
>> http://www.nws.noaa.gov/om/notification/tin07-59gfs_upgrade_unifiedpost.txt
>>
>>
>> Steve Chiswell
>> Unidata User Support
>>
>>
>> On Fri, 2007-09-28 at 10:01 -0700, Harry Edmon wrote:
>>> I have had a couple of users complain about changes in the GFS data
>>> starting with the 1200 UTC run on 25 September.  I notice there is a
>>> jump up in the size of the gempak files starting with that run.  Does
>>> anyone know of any changes?  If you are curious about what I am talking
>>> about, look at this page, which uses the 0.5 degree data:
>>>
>>> http://www.atmos.washington.edu/~hakim/loop.psp?url=~hakim/tropo/theta/
>>>
>>> Start the loop and look at the areas in white go from smooth to noisy
>>> with the 1200 UTC 25th run.  Another user is now having problems with
>>> his WRF initialization that he did not have before this.
>>>
>>>
>>> _______________________________________________
>>> conduit mailing list
>>> conduit at unidata.ucar.edu
>>> For list information or to unsubscribe, visit: http://www.unidata.ucar.edu/mailing_lists/
>> --
>> Steve Chiswell <chiz at unidata.ucar.edu>
>> Unidata
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>>
>
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