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