[gradsusr] plotting wind speed (or velocity) versus height rather than level number

[Muhammad Yunus Ahmad Mazuki]

Hi

z would refer to the lev (level), just as x would refer to lon and y refer
to lat. If your descriptor is 'zdef levels 1000 900 800', that means set z
1 would mean set lev 1000. That is unless you have 1000 levels in your
data.


On Thu, Jul 18, 2013 at 10:20 AM, John D. Wilson <jaydee.uu at ualberta.ca>wrote:

> Hi Ron,
>
> I'd been using "set z 1 45" (for instance). It never occurred to me I
> could specify in mb. However I've just now tried
>
> set x 38
> set y 38
> set z 1000 900
> d ugrdhlev
>
> and got
>
> Data Request Error: Invalid grid coordinates
>    Varying dimension 2 decreases: 1000 to 900
>    Error ocurred getting variable 'ugrdhlev'
>    Error ocurred at column 1
> DISPLAY error:  Invalid expression
>    Expression = ugrdhlev
>
> This is even though q ctlinfo returns
>
> ugrdhlev  58  0,2,2  ** (58 57 56 55 54.. 5 4 3 2 1) U-Component Of Wind
> [m/s]
>
>
> I also tried specifiying an interval for z in Pa -- similar complaint.
> John.
>
> On 17/07/13 18:02, Goodson,Ron [Edm] wrote:
> > Hi John
> >
> > If you original levels were in pressure or height or sigma .. then I'm
> surprised it doesn't plot that as the vertical coord (if that is what you
> meant). Pretend the vertical coord is in mb in your original data.  Did you
> do something like "set z 1 10" or did you do "set z 1000 500".  The latter
> should cause the vertical coord to be mb.
> >
> >
> > If, however, you actually want all those different coord systems, then
> you will have to interpolate U to the various levels you want .. using
> something like the grads-script "zinterp.gs" (in the script library)
> >
> >
> > Ron Goodson
> > Prairie and Northern Meteorological Service of Canada Science Section
> Unité des Sciences, Région des Prairies et du Nord, Service Météorologique
> du Canada
> > Environment Canada
> > Room 200 ; 4999 - 98 Avenue
> > Edmonton Alberta T6B 2X3      Environnement Canada
> > Pièce 200 ; 4999 - 98 Avenue
> > Edmonton Alberta T6B 2X3
> > Telephone | Téléphone 780 951 8791
> > Email | Courriel      ron.goodson at ec.gc.ca
> >
> >
> >
> > -----Original Message-----
> > From: gradsusr-bounces at gradsusr.org [mailto:
> gradsusr-bounces at gradsusr.org] On Behalf Of John D. Wilson
> > Sent: July 17, 2013 4:42 PM
> > To: gradsusr at gradsusr.org
> > Subject: [gradsusr] plotting wind speed (or velocity) versus height
> rather than level number
> >
> > Hi,
> >
> > I'd like to plot a wind profile at fixed (X,Y,t). It's straightforward
> to plot (for instance) the u-component versus level number (``d
> > ugrdhlev'') but I'd like instead to display u versus height, or u versus
> pressure, or u versus sigma. I expect this is really easy but I haven't yet
> stumbled on the trick. Can anyone help? Thanks, John
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>
>
> --
> J.D. Wilson (Prof)
> Rm. 3-277, CCIS Building
> Department of Earth & Atmospheric Sci.
> University of Alberta, Edmonton, AB T6G2E3
> 780 492 0353
>
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