[gradsusr] Vint fucntion - problem

[Bonan Antonino]

Sorry...

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-fq1'

Bye

Antonino Claudio Bonan
ARPAV- Servizio Meteorologico
Teolo (PD) - Italy----- Original Message ----- 
  From: Bonan Antonino 
  To: GrADS Users Forum 
  Sent: Friday, January 24, 2014 11:05 AM
  Subject: Re: [gradsusr] Vint fucntion - problem


  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


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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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