[gradsusr] Moisture flux convergence/divergence

[Hyacinth Nnamchi]

Arlindo thanks for your suggestions. I'll try them.Hyacinth
> 
> Message: 5
> Date: Sat, 17 Sep 2011 10:12:57 -0400
> From: Arlindo da Silva <dasilva at alum.mit.edu>
> Subject: Re: [gradsusr] Moisture flux convergence/divergence
> To: GrADS Users Forum <gradsusr at gradsusr.org>
> Message-ID:
> 	<CALz7xZf5MaHEvP1bX1Z93ysYNg5xVCGOvBdBaM5aHTkEs6+HSw at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> 2011/9/16 Hyacinth Nnamchi <hyacinth.1 at hotmail.com>
> 
> >  Jeff,
> >
> > I seems my question wasn't well framed, and so you dealt with the typo. I
> > have attached two Figs showing what the calculations below will give and
> > what exactly I'll like to do.
> >
> >
> >From the attached plot it appears that you want to plot the divergent
> component of the mass flux, as given by the Helmholtz decomposition:
> 
>            http://en.wikipedia.org/wiki/Helmholtz_decomposition
> 
> The first step is to compute the velocity potential
> 
>    ga-> chi = fish_chi(zon,mer)
> 
> (As Roger mentions, make sure to average in the vertical first if this is
> what you want.) Next, the divergent component of the mass flux is related to
> the gradient of chi; see this for more information:
> 
>  Calculating the Divergent
> Wind<http://opengrads.org/doc/udxt/fish/fish.html#calculating_the_divergent_wind>
> 
> Notice that you will need an opengrads build in order to use the fish
> extension; more info here:
> 
>     http://opengrads.org/wiki/index.php?title=Installing_the_OpenGrADS_Bundle
> 
>  Good luck,
> 
>    Arlindo
> 
> 
> 
> 
> 
> 
> > Thanks,
> >
> > Hyacinth
> >
> >
> > > Date: Thu, 15 Sep 2011 17:34:50 -0500>
> > From: Jeffrey Duda <jdduda at iastate.edu>>
> >  Subject: Re: [gradsusr] Moisture flux convergence/divergence
> > > To: GrADS Users Forum <gradsusr at gradsusr.org>
> > > Message-ID:
> > > <CAP9LQ-VNkxcu-+ey_QkZU7f4MHf+VwJDvav=Dci3ns+x+pjG8Q at mail.gmail.com>
> > > Content-Type: text/plain; charset="iso-8859-1"
> >
> > >
> > > Set the graphics output to vector ('set gxout vector'), then 'd zon;mer'
> > > (note the semicolon instead of a comma).
> > >
> > > Jeff Duda
> > >
> > > 2011/9/15 Hyacinth Nnamchi <hyacinth.1 at hotmail.com>
> > >
> > > > Hello,
> > > >
> > > > This is not directly about GrADS but since most of address similar!
> > > > problems, I guess someone on this forum will be able to answer my
> > question.
> > > >
> > > > I understand that to calculate moisture transport, given zonal,
> > meridional
> > > > winds and specific humidity, can simply do:
> > > >
> > > > 'define zon=uwnd.1*shum.3'
> > > > 'define mer=vwnd.2*shum.3'
> > > > 'd zon,mer'
> > > >
> > > > But, I want to plot vectors indicating field of net moisture flux (all
> > arrows converging/diverging) instead of just transport.
> > > >
> > > > Thanks for any ideas.
> > > >
> > > > Hyacinth
> > > >
> > > >
> > > > __
> >
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> >
> 
>> ****************************************
 		 	   		  
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