[gradsusr] Question about srh1km(uVAR,vVAR) function

[Nimrod Micael]

@Jeff:

Ok because I find it weird that my 0-1 KM shear values at 16Z in GSO is
about 1/2 of the value of the observation from a sounding taken at the time
when using that shr1km(u,v) function. However, when I used Rob Hart's
plotskew script to plot the sounding...the ERSH matched closer to the
observation at that time. So I am wondering why such a huge error in that.


On Sat, Sep 7, 2013 at 2:08 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:

> If you're calculating 0-1 km SRH over flat terrain near sea level, their
> computation is within reason.  However, if you're on higher terrain or
> sloped terrain (e.g., the Plains region of the US), you'll want to use a
> different method.
>
> Jeff
>
>
> On Sat, Sep 7, 2013 at 11:28 AM, Nimrod Micael <nmicael at aggies.ncat.edu>wrote:
>
>> He stated it's 1 KM MSL.
>>
>>
>>
>> "However, the question of AGL or MSL depends on your model data output -
>> if it compensates the pressure height. GFS IIRC does not do that, so it
>> would be MSL.
>>
>> To understand the calculation, you can check the original math from our
>> website:
>> http://www.saakeskus.fi/grads-scripts/63-storm-relative-helicity-0-3km"
>>
>> So in order to calculate 0-1 KM shear it has to be 0-1 KM AGL?
>>
>>
>> Thanks.
>>
>>
>>
>>
>> On Fri, Sep 6, 2013 at 1:30 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:
>>
>>> I don't use openGrads, so there may be some specifics I'm not aware of.
>>> uVAR and vVAR are just dummy names for the u- and v-components of the
>>> wind.  The inaccuracies are probably due to the exact specifics with how
>>> the 0-1 km shear is computed in the script.  One big question is how is the
>>> 1 km layer wind field being computed?  Is it just 1 km MSL or 1 km AGL?
>>> Those are things you need to find out.  I recommend asking the authors
>>> whose email addresses are given on the linked page.
>>>
>>> Jeff
>>>
>>>
>>> On Fri, Sep 6, 2013 at 12:20 PM, Nimrod Micael <nmicael at aggies.ncat.edu>wrote:
>>>
>>>> *srh1km*(*uVAR,vVAR*)
>>>> What is uVAR and vVAR?  I dont have those variables.
>>>>
>>>> http://opengrads.org/doc/udxt/saakeskus/
>>>>
>>>> I tried replacing uVar and vVar with u and v wind but I am getting some
>>>> inaccuracies with the 0-1 KM shear. Can someone help me out?
>>>>
>>>> Thanks.
>>>>
>>>> --
>>>> Nimrod Micael
>>>>
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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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>>>
>>
>>
>> --
>> Nimrod Micael
>>
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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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>


-- 
Nimrod Micael
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