[gradsusr] Vint fucntion - problem

[Jeff Duda]

Check example #2 in the documentation for the vint function:

2. This is an artificial example that demonstrates a vertical integration
from a fixed lower bound of 1000mb to the top of the atmosphere, and
integrating a field of all 1's. This gives an answer of 10204.1 (or
100000/9.8) which is the mass of air (in kg) of a 1 meter squared column
when the surface pressure is 1 bar and the accelleration due to gravity is
assumed to be exactly 9.8m/sec**2 over the entire column.

   vint(const(ps,1000),const(t,1),0)


Grads is probably having a hard time figuring out what you mean by 'lev' in
the first argument.  My guess is the same numerical values of lev are being
used in each of the three commands.  The value is probably 1000, so in
effect you are integrating over progressively deeper layers, which is why
you are getting fqu1 < fqu2 < fqu3 for example.  I would try changing the
first argument to something like const(p,1000), const(p,700), const(p,500)
etc.

Jeff Duda





On Thu, Jan 23, 2014 at 1:17 PM, °° Maytê °° . <mayteleal at hotmail.com>wrote:

>
> Hi,
>
> I'm trying to calculate the transport and convergence of moisture flux
> integrated in three layers of the troposphere. Define the layers as
> follows:
>
> * Lower troposphere
> :
> 'set lev 1000'
> 'defines fqu1 vint = (lev, q*u, 850)'
>
> * Middle troposphere:
> 'set lev 700'
> 'defines fqu2 vint = (lev, u*q, 500)'
>
> * High Troposphere:
> 'set lev 500'
> 'defines fqu3 vint = (lev, u*q, 300)'
>
> The same for fqv1, fqv2 and fqv3...
>
> For then, the values at low levels are lower than in the middle and
> upper troposphere.
> Is there another way to calculate?
>
> Something is wrong, since I reviewed all the steps and the only change I
> make is the 'lev'.
> Before had done the integration from 1000 to 300 hPa and not had any
> problem.
>
> thank you,
> May
>
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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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