Add arrows to surface plot to represent wind direction

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mashtine 2015-9-23

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https://ww2.mathworks.cn/matlabcentral/answers/244715-add-arrows-to-surface-plot-to-represent-wind-direction

评论： mashtine 2015-9-24

Hi there,

I am seeing a lot of information about the quiverm function but I only have my wind direction data in degrees and not in the u and v components. Is there a simple way to project a matrix of wind direction values (360 degrees) onto a sufacem plot? Perhaps there is a way to add and arrow and align it based on the wind direction value? I do not want to add magnitude as well, just direction.

Many thanks,

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mashtine 2015-9-23

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Hi Kirby,

I believe the NCL website is giving the correct data as it will produce the correct wind direction for the negative quadrants. I am also getting the expect wind direction (easterly winds). For instance,

atan2(sind(181),cosd(181))*r2d
ans =
    -179

where I should not be getting a negative direction but degrees in 0 to 360. I believe it is accounting for matlab use of the atan2 function as this differs in some software

Kirby Fears 2015-9-23

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-179 is the correct answer.

-179+360=181

The NCL website adds 180 to this, which would be

-179+180=1, which is incorrect.

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采纳的回答

Kirby Fears 2015-9-23

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编辑：Kirby Fears 2015-9-23

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I'm posting an example as described in my earlier comment.

Code below creates a 10x10 grid of arrows that are all pointing at 120 degrees.

x=repmat(1:10,10,1);
y=x';
deg=120; % all points have same direction
% if you have a degree array the same size as x, 
% you can use cosd and sind on "deg" without
% using repmat after
u=repmat(cosd(deg),size(x)); 
v=repmat(sind(deg),size(x));
% you can multiply u and v by magnitude of required
quiver(x,y,u,v);