[gradsusr] How to calculate integrated water Vapor transport

[Jeff Duda]

Are you sure your input fields have the correct (SI) units? Also, i don't
know what grads formula you're using to perform the integral, but vint()
assumes pressure coordinates in *millibars* rather than Pascals, so that
may be a source of your problem.

I don't work with IVT, and the formulas I found online don't match what you
indicated, so I can't say for sure if the problem is with the formulation
or not.

Jeff Duda

On Wed, Nov 13, 2019 at 8:39 PM kalyan chakravarthy <kalyan4space at gmail.com>
wrote:

> Hello Everyone,
>
> I need some help to calculate Integrated Water vapor transport (IVT) from
> surface to 300hPa.  I am using ERA-Interim data (uwind (u), vwind(v),
> specific humidity(q)). I have used the scripts that are published in the
> grads user forum, but the results seems wrong (ex. the values are from
> 40000 kg/ms).
>
> The formula I am using to calculate the IVT is
>
> IVT=Sqrt((integral(q*u)*dp)^2+((integral(q*v)*dp)^2)
>
> Integration is from Surface to 300 hPa.
>
>
> Thanks
>
> Kalyan
>
>
> --
> *Kalyan Chakravarthy Yesoda*
>
> Graduate Student, PhD
> University of Nevada, Reno
> Mobile no: 775-420-9434
>
>
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-- 
Jeff Duda, Research Scientist
University of Colorado Boulder
Cooperative Institute for Research in Environmental Sciences
NOAA/OAR/ESRL/Global Systems Division
Boulder, CO
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