[gradsusr] VGP (Vorticity Generation Parameter)

[Jeff Duda]

You should look up the scholarly reference on VGP: Rasmussen, E.N., and
D.O. Blanchard, 1998: A baseline climatology of sounding-derived supercell
and tornado forecast parameters. *Wea. Forecasting*, *13*, 1148-1164. The
definition of mean shear is clearly defined in section 3c.

Jeff Duda

On Mon, Sep 28, 2015 at 2:35 PM, Daniel Nairn <dannairn at gmail.com> wrote:

> Thanks, I was only /1000 so that looks a little more 'realistic' now. I
> don't know how to script the mean shear component so I'll see how this goes
> with bulk shear. Thanks for your help.
>
> On 28 September 2015 at 16:39, L.B. <bcbass2989 at gmail.com> wrote:
>
>> I just use 0-3km bulk shear, and use the formula:
>>
>> define vgp3 = (sqrt(CAPE)*shr3)/3000)'
>>
>> To calculate mean shear though, you would need to sum up the shear values
>> through that layer and divide by that many levels. For 0-3km, the surface
>> to 700mb range is a good proxy, although keep in mind that your values will
>> be off in higher elevations.
>>
>> *-------*
>>
>> *William (L.B.) LaForce*Meteorologist
>> www.tornadoinsanity.com
>>
>> On Mon, Sep 28, 2015 at 11:01 AM, Daniel Nairn <dannairn at gmail.com>
>> wrote:
>>
>>> Hi
>>>
>>> Has anybody successfully written a script to display VGP through GrADS?
>>> I have a script almost working, though its currently using 0-3km *bulk
>>> shear*, rather than the correct 0-3km *mean shear*. I'm not sure how to
>>> calculate the 0-3km mean shear value through GrADS, does anybody know how
>>> to do this?
>>>
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>>
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-- 
Jeff Duda
Graduate research assistant
University of Oklahoma School of Meteorology
Center for Analysis and Prediction of Storms
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