[gradsusr] W vector on north-south transect

Mon Sep 15 15:36:00 EDT 2014

Jeff/Jonathan,

The rendering of vectors is done by specifying the two components: 
magnitude and direction, or horizontal and vertical components.  In your 
original script you have:

'd skip(c,6,3);skip(u,6,3)'

I believe this will use the variable "c" as the horizontal component of 
the vector and "u" as the vertical.  In your case the horizontal is 
latitude and vertical is altitude.  In other words I don't think your 
original script is plotting vertical motion. Ditto the suggestion for 'd 
W;0*W',  which I think will give you vertical velocity plotted as 
horizontal vectors.  Instead I think you want 'd 0*W;W' (or 'd c*0;c').

Jim

On 9/15/14 8:53 AM, Jeff Duda wrote:
> Jonathan,
> Oh, I see what you're saying.  Yes, it appears the vectors in your 
> figure accurately depict the vertical motion.
>
> To display vectors, you must use the field1;field2 syntax. But you can 
> manipulate one of the fields to display 1-D vectors.  Just make one of 
> the fields a zero field.  For example, you could display the vertical 
> motion alone using
> 'd W;0*W'
>
> Jeff
>
> On Mon, Sep 15, 2014 at 1:35 PM, Jonathan Wynn Smith 
> <jwsmith9 at gmail.com <mailto:jwsmith9 at gmail.com>> wrote:
>
>     Are you saying the vectors that I have in the figure accurately
>     depict the vertical motion?
>
>     I do not want to display 3-d variables.  Just the vertical motion
>     vector: W.
>
>     Unless I have some procedure wrong, the vectors in the figure will
>     not display with just W.
>
>     For example:
>
>     cannot use
>     d W
>
>     must use
>     d W,U or d W,V
>
>     for vectors to display.  Why is this?
>
>     Jonathan
>
>     On Mon, Sep 15, 2014 at 1:43 PM, Jeff Duda <jeffduda319 at gmail.com
>     <mailto:jeffduda319 at gmail.com>> wrote:
>
>         Jonathan,
>         I'm not sure I understand the difficulty you are facing. 
>         GrADS cannot display three-dimensional vectors, so if you want
>         to visualize all three components to the wind, one of them
>         will have to be displayed as contours rather than as vectors. 
>         The plot you attached makes sense if you want to look at
>         advection of carbon monoxide along a north-south vertical
>         cross section.
>
>         Please clarify the problem.
>
>         Jeff Duda
>
>         On Mon, Sep 15, 2014 at 12:33 PM, Jonathan Wynn Smith
>         <jwsmith9 at gmail.com <mailto:jwsmith9 at gmail.com>> wrote:
>
>             Good afternoon:
>
>             'a = ave(U.1,t=289,t=1008,1)*100'
>             'b = ave(V.1,t=289,t=1008,1)*100'
>
>             'c = ave(W.1,t=289, t=1008)*100'
>             "xcbar 1 10 0.3 0.5 -fw 0.175 -fh 0.175 -line on"
>
>
>             "set gxout vector"
>             'd skip(c,6,3);skip(u,6,3)'
>
>
>             Above, GrADS is displaying a north-south transect of
>             carbon monoxide with vertical motion vectors.
>
>             The W variable will not display vectors by itself. I
>             actually will display W contours but I need vectors. It
>             seems that there has to be one of the horizontal variables
>             displayed in conjunction W for vectors to display.  I
>             chose U in the above case.  Does this mean the U component
>             of the vertical wind?
>
>             Is it possible to print out the W vectors without the U or
>             V components?
>
>             I have attached a figure of what I am referring to.
>
>             Thanks
>             Jonathan
>
>             -- 
>             *Jonathan Wynn Smith, Ph.D.*
>             jonathan.smith at noaa.gov <mailto:jonathan.smith at noaa.gov>
>             301-683-0500 <tel:301-683-0500>
>             Postdoctoral Research Associate
>             National Academy of Science/National Research Council
>             Associateship
>             NOAA/NESDIS/STAR/SMCD, #2844
>             5830 University Research Ct.
>             College Park, MD 20740-3818
>             /
>             Lord, you establish peace for us; all that we have
>             accomplished you have
>             done for us. - Isaiah 26:12/
>
>
>
>
>
>
>
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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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>
>
>
>     -- 
>     *Jonathan Wynn Smith, Ph.D.*
>     jonathan.smith at noaa.gov <mailto:jonathan.smith at noaa.gov>
>     301-683-0500
>     Postdoctoral Research Associate
>     National Academy of Science/National Research Council Associateship
>     NOAA/NESDIS/STAR/SMCD, #2844
>     5830 University Research Ct.
>     College Park, MD 20740-3818
>     /
>     Lord, you establish peace for us; all that we have accomplished
>     you have
>     done for us. - Isaiah 26:12/
>
>
>
>
>
>
>
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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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