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20020512: gdplot wind component in specified direction

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  • Subject: 20020512: gdplot wind component in specified direction
  • Date: Mon, 13 May 2002 07:49:58 -0600
>From: Cheryl Lacotta <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200205130524.g4D5O8a13975

>I am trying to plot the component of the wind in a specified direction,
>say 140 degrees, on a grid.  Since there is no parameter similar to
>SNPLOT's "WCMP" in GDPLOT, I would think the simplest way to do this is
>to dot the wind vectors into a vector in the specified direction, but I
>wouldn't know how to specify that vector.  Any ideas?
>
>Cheryl
>

Cheryl,

If you wanted to compose a vector, you could use the VECN(S1,S2) function
where S1 and S2 would be your components. For a unit vector with direction
of 140, the DOT(V1,V2) might look like:

GFUNC=dot(wnd,vecn(.6428,-.7660)) 

Another GEMPAK function is VASV(V1,V2) which is useful if you wanted to 
determine
V1 along V2.

Steve Chiswell