[gradsusr] Plotting EP Fluxes in GrADS

[Jeff Duda]

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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