[gradsusr] Plotting EP Fluxes in GrADS

[Jason Furtado]

Do you mean insert a '-' on the flux: d skip(epy,2,1);skip(-epz,2,1)

If not, how do you flip the sign of the vertical coordinate (note: I 
still want pressure to descend upwards and be on a log scale)?

- Jason

On 9/5/12 5:19 PM, Jeff Duda wrote:
> 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 
> <mailto: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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-- 
Jason C. Furtado, Ph.D.
Staff Scientist
Atmospheric and Environmental Research (AER), a Verisk Analytics company
131 Hartwell Ave.
Lexington, MA 02421

E-mail:  jfurtado at aer.com
Phone:  781-761-2384

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