[gradsusr] How to calculate the pressure gradient?

[Jeff Duda]

Djordje,
Since cdiff performs a centered difference, if you use the expressions
suggested by another Grads user on this thread, you would only want to use
dx since 2*dx is already implied in the definition.

Jeff

On Thu, Aug 9, 2012 at 1:50 AM, Djordje Romanic <djordje8 at gmail.com> wrote:

> Thanks,
>
> Since I only need the pressure gradient, and not the pressure gradient
> force, I should exclude 1/rho. Just one clarification. When I use cdiff
> function for pressure (e.g. in LON direction), should I divide it with dx
> or 2*dx. I believe that 2*dx would be correct.
>
> Regards,
> Djordje
>
>
> On Wed, Aug 8, 2012 at 7:08 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:
>
>> The pressure gradient is simply 1/rho * del(p), where del(p) is the
>> gradient operator, which can be displayed in Grads using the mathematical
>> decomposition of the gradient operator (i.e., derivatives in the x- and
>> y-directions).  Use cdiff for those derivatives.  Note, you'll have to
>> define your x- and y- grid spacing values as well.  See the examples on the cdiff
>> help page <http://www.iges.org/grads/gadoc/gradfunccdiff.html> for how
>> to do that.
>>
>> Jeff Duda
>>
>> On Wed, Aug 8, 2012 at 5:48 AM, Djordje Romanic <djordje8 at gmail.com>wrote:
>>
>>> Dear Users,
>>>
>>> I have to calculate the pressure gradient in a given area (Southeast
>>> Europe) and I have a pressure date at 2.5 x 2.5 degrees (reanalysis data).
>>> Does anyone know how to calculate it in GrADS and how to show the results
>>> in the vector form?
>>>
>>> Thanks in advance.
>>>
>>> Regards,
>>> Djordje Romanic
>>> M.Sc. in Meteorology
>>> Cell: +38164 254 3539
>>> www.linkedin.com (Djordje Romanic profile)
>>>
>>>
>>> _______________________________________________
>>> gradsusr mailing list
>>> gradsusr at gradsusr.org
>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>
>>>
>>
>>
>> --
>> Jeff Duda
>> Graduate research assistant
>> University of Oklahoma School of Meteorology
>> Center for Analysis and Prediction of Storms
>>
>>
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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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