[gradsusr] Plotting EP Fluxes in GrADS

Jeff Duda jeffduda319 at gmail.com
Wed Sep 5 17:19:39 EDT 2012


What about just flipping the sign of the vertical coordinate in the display
command? If you do that, do the vectors match up?

Jeff

On Wed, Sep 5, 2012 at 3:31 PM, Jason Furtado <jfurtado at aer.com> wrote:

> All -
>
> I am running into an issue with plotting EP flux vectors on the
> latitude-by-pressure plane in GrADS.  I did the calculations in another
> language and wrote out relevant data (EPy, EPz, and the divergence of
> the flux) to a binary file to load and plot in GrADS.   I have checked
> my plot against a plot that I can generate on the NCEP website and the
> vertical direction of the arrows is reversed (they point down in the
> GrADS plot but should point up according to the NCEP plot).
>
> Having checked the values plotted in GrADS (using gxout grid), many of
> the values of EPz are negative.  According to the Edmon et al. (1980)
> paper, in pressure coordinates, positive (negative) EPz should point
> toward higher (lower) pressure.  Is this an issue with GrADs?  Anyone
> else run into this issue?  My (abbreviated) script is below.
>
> reinit
> set background 1
>
> open epfluxes_epdiv_2009_2010_obs.ctl
>
> set t 390 390
> set lat 10 90
> set vpage 0 11 0 6
> set annot 0
>
> set gxout vector
> set zlog on
> set z 1 17
> set xaxis 10 90 10
> set xlabs 10N|20N|30N|40N|50N|60N|70N|80N|90N|
> set ylevs 10 50 100 300 500 1000
> set grads off
> set grid off
> set font 1
> set ylopts 0 4 0.2
> set xlopts 0 4 0.2
>
> set arrscl 1 200
> set ccolor 2
> set cthick 6
> set arrowhead -0.25
> set arrlab on
> set grid off
> d skip(epy,2,1);skip(epz,2,1)
>
> Thanks!
> - Jason
> --
> Jason C. Furtado, Ph.D.
> Staff Scientist
> Atmospheric and Environmental Research (AER), a Verisk Analytics company
> 131 Hartwell Ave.
> Lexington, MA 02421
>
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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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