[gradsusr] Wind Arrow

[Hui Wang - NOAA Affiliate]

Hi Olivier,

When you use
'set gxout vector'

you can use
'set arrowhead size'

http://www.iges.org/grads/gadoc/gradcomdsetarrowhead.html

If 'size' is set to a negative value, the size of the arrowhead will be
proportional to the wind speed.

Thanks,
Hui



On Sun, Oct 19, 2014 at 11:23 PM, Olivier TRECA <otreca at me.com> wrote:

> Hi Tom,
>
> Thank you for your answer but it’s not really what I want to do. I have
> already tested vector but that arrow is not very nice.
>
> The arrow I want to make are like in the picture attached.
>
> Do you have a method to do that ?
>
> Le 19 oct. 2014 à 21:46, Thomas Robinson <ter at hawaii.edu> a écrit :
>
> Aloha Olivier,
>
> If you use 'set gxout vector' it will plot wind vector arrows.
>
> If you use
> 'set gxout vector'
> 'd u;v;mag(u,v)'
> where u and v are your wind components, the arrows will be colored based
> on the wind speed.
>
> If it's too dense, you can use skip to plot less arrows
> 'set gxout vector'
> 'd u;skip(v,10,10);mag(u,v)'
>
> You can use cbar to see what speeds the colors match up to.
>
> Good luck,
> -Tom
>
>
> On Sun, Oct 19, 2014 at 7:25 AM, Jeff Duda <jeffduda319 at gmail.com> wrote:
>
>> Olivier,
>> You'll probably want to use a combination of maskout() and set strmden
>> <http://www.iges.org/grads/gadoc/gradcomdsetstrmden.html> to control the
>> appearance of the arrowheads on a streamline plot.  The maskout() function
>> will plot a set of streamlines in an area corresponding to whatever speed,
>> direction, or other threshold you want (sounds like you want to use speed
>> as a threshold), and all of the streamlines plotted will correspond to the
>> current 'set strmden' settings.  Between each display command you will want
>> to re-enter the 'set strmden' command with different settings and use
>> different thresholds in the maskout() function.
>>
>> Jeff Duda
>>
>> On Sun, Oct 19, 2014 at 5:11 AM, Olivier TRECA <otreca at me.com> wrote:
>>
>>> Hello,
>>>
>>> My name is Olivier and I’m from France. I use GrADS to make the maps
>>> which describe the weather and the migration of the birds.
>>>
>>> Could see my map on this site :
>>>
>>> http://www.chasseurdemigrateurs.com/meteo/view/2014/10/19
>>>
>>> The wind is important but I don’t have found how to make cute arrows and
>>> so I use the streamlines. But I’m not happy.
>>>
>>> What I want to make is small arrows when the wind is light and big one
>>> filled for example in red when the wind is stronger.
>>>
>>> I think it could be possible drawing a rectangle and a triangle at the
>>> right place and with the right size… but I’m not aware with this type of
>>> manipulation.
>>>
>>> If somebody could help me !
>>>
>>> Many thanks
>>>
>>> Olivier TRECA
>>> otreca at me.com
>>>
>>>
>>> <PastedGraphic-2.tiff>
>>>
>>>
>>> _______________________________________________
>>> gradsusr mailing list
>>> gradsusr at gradsusr.org
>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>
>>>
>>
>>
>> --
>> Jeff Duda
>> Graduate research assistant
>> University of Oklahoma School of Meteorology
>> Center for Analysis and Prediction of Storms
>>
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>>
>>
>
>
> --
> Tom Robinson
> Treasurer - Graduate Student Organization
> Secretary - Student Athletic Fee Committee
> Graduate Student - Department of Atmospheric Science
> 732-718-2323
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