[gradsusr] using fish_psi and chi

[Arlindo da Silva]

On Mon, Jun 21, 2010 at 10:58 AM, Giovana Luz <luzgiovana at hotmail.com>wrote:

>  Hello all,
>
>
> I've tried to use fish function, to calculate streamfunction (fish_psi)
> and velocity potential (fish_chi), I get to use, but results are different
> of website that I compare, using the same data and time.
>
> *************
>
> 'sdfopen uwnd.mon.mean.nc'
> 'sdfopen vwnd.mon.mean.nc'
>
> 'set t 1 last'
>
> 'set z 10' ***200 hpa
>
>
> *streamfunction
> 'define psi = fish_psi(uwnd,vwnd.2)'
>
> *velocity potential
> 'define chi = fish_chi(uwnd,vwnd.2)'
>
> **************
> someone could help me?
>
>
Streamfunction and velocity potential are defined up to an arbitrary
constant. It is common practice to remove the global mean, e.g.,

ga-> d chi - aave(chi,global)

This is mentioned in the documentation:

         http://opengrads.org/doc/udxt/fish/

                Arlindo



> Thanks,
>
> Giovana Luz
> ______________________________________________
>
> Departamento de Geografia - DG
> Faculdade de Filosofia, Letras e Ciências Humanas - FFLCH
> Universidade de São Paulo - USP
>
>
>
>
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-- 
Arlindo da Silva
dasilva at alum.mit.edu
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