[gradsusr] Wind Barbs

[Stephen McMillan]

Hi Andy,

Adding to what Jeff and Sam submitted, you can use the maskout function to
hide the "calm" wind amounts.  For example,

'define wspd=1.944*mag(ugrdprs,vgrdprs)'
'set gxout barb'
'd maskout(1.944*ugrdprs,wspd-3);1.944*vgrdprs'

In above example, wind speed is first defined over the time interval, then
used to maskout one of the wind components (u in this example).  Here I
defined speeds < 3 as calm, but use whatever suits your case.  Variable
names a bit different in my example.


Stephen McMillan


On Wed, Aug 21, 2013 at 12:25 PM, Sam Wilson <sam at surfline.com> wrote:

>   Andy,
>
>  For your second question – it looks like you're only applying the m/s to
> knot conversion to the v component.  Try the following:
>
>   'd (u500;v500)*1.94384'
>
>   Either that way or this way:
>
>  'define uwind = u500*1.94384'
> 'define vwind = v500*1.94384'
> 'd uwind;vwind'
>
>
>  Sam
>
>   From: Andrew Revering <andy at f5data.com>
> Reply-To: GrADS Users Forum <gradsusr at gradsusr.org>
> Date: Wed, 21 Aug 2013 10:07:28 -0500
> To: GrADS User List <gradsusr at gradsusr.org>
> Subject: [gradsusr] Wind Barbs
>
>  Couple questions about wind barbs:
>
>  - Is it possible to plot 'nothing' where a calm wind barb would go?
> Right now it shows a circle or a zero where calm wind is. I'd rather it
> plot nothing in those locations.
>
>  - Also, the speed is incorrect in my wind barbs. I'm trying to plot it
> in knots and I'm using: 'display u500;v500*1.94384'
> The mag() function returns different values than what is being plotted for
> my barbs, so apparently I'm not converting my wind barb from m/s to knots
> properly. Thoughts?
>
>  Thanks,
> Andy
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