[gradsusr] Vint fucntion - problem

[Bonan Antonino]

Try this:

'set z 1 last'
*where "last" is the total number of levels
'fq1=vint(ps,q*u,850)'
*where ps is your surface pressure field
'fq2=vint(ps,q*u,500)-fq1'
'fq3=vint(ps,q*u,300)-fq2'

Bye

Antonino Claudio Bonan
ARPAV- Servizio Meteorologico
Teolo (PD) - Italy
----- Original Message ----- 
  From: Jeff Duda 
  To: GrADS Users Forum 
  Sent: Thursday, January 23, 2014 8:26 PM
  Subject: Re: [gradsusr] Vint fucntion - problem


  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


    _______________________________________________
    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



------------------------------------------------------------------------------


  _______________________________________________
  gradsusr mailing list
  gradsusr at gradsusr.org
  http://gradsusr.org/mailman/listinfo/gradsusr
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20140124/2966ddb1/attachment.html