[gradsusr] Question about why the wind vectors barbs not showing up for the 0-6 KM Shear difference

[Jeff Duda]

You're still only displaying a scalar quantity.  You need to display the
shear components separated by a ; to get the barbs to appear.


On Mon, Sep 2, 2013 at 10:39 AM, Nimrod Micael <nmicael at aggies.ncat.edu>wrote:

> oh u10 and v10 is
>       u10  1  0  U at 10 M (m s-1)
>       v10  1  0  V at 10 M (m s-1)
> respectively.
>
>
> On Mon, Sep 2, 2013 at 11:29 AM, Nimrod Micael <nmicael at aggies.ncat.edu>wrote:
>
>> Actually I think I fixed the problem but still didnt get the wind barb...
>>
>>  zinterp(u,height,6)
>>  'u6km=interp'
>>  zinterp(v,height,6)
>>  'v6km=interp'
>>  'shear0006=1.94*mag(u6km-u10,v6km-v10)'
>>  'set gxout shaded'
>>  'set cmin 20'
>>  'd shear0006'
>>
>>
>>  'set gxout barb'
>>  'set cmin 20'
>>  'd shear0006'
>>
>>
>> What's going on?
>>
>>
>> On Mon, Sep 2, 2013 at 1:40 AM, Nimrod Micael <nmicael at aggies.ncat.edu>wrote:
>>
>>> Oh my model height is in KM though. Hence why 6 KM and not 600 meters.
>>>
>>>
>>> On Mon, Sep 2, 2013 at 1:39 AM, Nimrod Micael <nmicael at aggies.ncat.edu>wrote:
>>>
>>>> The interpolation is not working for me.
>>>>
>>>> I did this:
>>>>
>>>> 'umid=zinterp(u,height,6)'
>>>>  'vmid=zinterp(v,height,6)'
>>>>  'ulow="zinterp(u,height,0)'
>>>>  'vlow="zinterp(v,height,0)'
>>>>  'verticalshear =(umid-ulow)+(vmid-vlow)'
>>>>  'bulkshear=sqrt(verticalshear)'
>>>>
>>>>
>>>> Still not getting anything after many tries.
>>>>
>>>>
>>>> Thanks!
>>>>
>>>>
>>>> On Sun, Sep 1, 2013 at 11:35 PM, Nimrod Micael <nmicael at aggies.ncat.edu
>>>> > wrote:
>>>>
>>>>> Ohhhhh @Jeff...I see what you are saying...there's an angle to the
>>>>> direction of the winds...you cant assume that both levels are in the same
>>>>> direction. That makes perfect sense. Very excellent explanation by the way.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Sun, Sep 1, 2013 at 10:52 PM, Jeff Duda <jeffduda319 at gmail.com>wrote:
>>>>>
>>>>>> I suggest you have a look through this page (
>>>>>> http://mathworld.wolfram.com/VectorAddition.html) and the related
>>>>>> page linked under "see also" called "vector difference".  You can
>>>>>> add/subtract two vectors by adding/subtracting the corresponding *
>>>>>> components* (i.e., the u and v components), and making a vector of
>>>>>> the resulting sum/difference.  What you seem to be stuck on is taking the
>>>>>> difference of the *magnitude* of the vectors rather than the
>>>>>> difference of the components.
>>>>>>
>>>>>> I'll use this example to help illustrate this.  Suppose you had a
>>>>>> westerly wind at 500 mb of 50 kts, and an easterly wind of 50 kts at the
>>>>>> surface (unlikely except for possibly within a severe thunderstorm, but
>>>>>> just bear with me).  There is no difference in the wind speed between 500
>>>>>> mb and the sfc, but there is a difference in the direction.  Clearly there
>>>>>> is shear, but only if you look at the component form of the wind.  The u-
>>>>>> and v-components of the 500 mb wind in this example are u = 50, v = 0
>>>>>> (kts), whereas at the surface, the components are u = -50, v = 0 (kts).
>>>>>>  Therefore, the shear is given by (u500-usfc)*i* + (v500-vsfc)*j* =
>>>>>> (50 - -50)*i* + (0-0)*j* = 100*i* + 0*j*.  The shear vector is
>>>>>> straight out of the west here.  The magnitude is given by sqrt(ushear^2 +
>>>>>> vshear^2), which is sqrt(100^2 + 0^2) = 100 kts of shear.
>>>>>>
>>>>>> Jeff
>>>>>>
>>>>>> _______________________________________________
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>>>>>> gradsusr at gradsusr.org
>>>>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Nimrod Micael
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Nimrod Micael
>>>>
>>>
>>>
>>>
>>> --
>>> Nimrod Micael
>>>
>>
>>
>>
>> --
>> Nimrod Micael
>>
>
>
>
> --
> 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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