How to calculate mean wind direction

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Jenna Marie
Jenna Marie 2014-5-5
评论： Soeren Bilges 2023-2-10
Hello!
I need help figuring out how to calculate mean wind direction when my data is in degrees (0-360). I just realized my current program does not take into account that the data is circular, and the mean of 355 and 5 will be 180, instead of 0. Any help is greatly appreciated! I am a beginner when it comes to MATLAB programming
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Jenna Marie
Jenna Marie 2014-5-5
Ah yes thank you for catching that! Accidentally mixed up 360 degrees in a circle with 365 days in a year. It's been a long day....

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采纳的回答

José-Luis
José-Luis 2014-5-5
average = mod(sum(data),360)./numel(data)
Please accept an answer if it helped you.
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Naseef Muhammed
Naseef Muhammed 2022-9-12
@Walter Roberson I'm refering to the function 'windir_avg' you provided above. In that function, if we given 2 anlges from third or fourth, it will give a wrong answer. for example, if we put 345 and 355 the answer will be 190. similarly, 240 and 250 will result in 295. I hope it can be resolved if we edit your script as below:
function [windir_avged] = windir_avg(windir)
windir_avged=180/pi*angle(sum(exp(1i.*windir.*pi/180))/numel(windir));
if windir_avged < 0
windir_avged=windir_avged+360;
end

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更多回答（3 个）

Jenna Marie
Jenna Marie 2014-5-5
Thank you so much for your response!
What does numel mean?
Walter Roberson
Walter Roberson 2017-7-9
See unwrap() but you will need to convert to radians
Robert Daly
Robert Daly 2021-6-16
I needed a solution that would ignore NAN values in the data.
Converts the direction data into X & Y vector components, averages those, then converts back to direction.
function [windir_avged] = windir_avg(windir)
[x,y] = pol2cart(deg2rad(windir),ones(size(windir)));
x=mean(x,'omitnan');
y=mean(y,'omitnan');
[windir_avged,~]=cart2pol(x,y);
windir_avged = rad2deg(windir_avged);
end

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