how to calculate fourier analysis in Polar coordinates

From: <yangtao7568_at_nyahnyahspammersnyahnyah>
Date: Tue Jun 10 2014 - 21:20:40 MDT

Hi NCL-talk,

            I encounted a question when I used function ezfftb/ezfftf to calculate fourier decomposition because of my reasons. And my specific questions were as follows. I had a array A ((/41,41/),float) which was grid data and then carried on calculating fourier analysis, but the outcome(appendix figure) was not what I wanted. Because I want to study the axisymmetric structure of tropical cyclone, but I don't know how to achieve it specifically. Firstly, I just wanted to convert data from grid data A ((/41,41/),float) in Cartesian coordinates to array B in Polar coordinates which was in the center of (20,20) dot. Secondly, every value of array B would minus the mean value which was calculated in the radius ring. Thirdly, I wanted to interpolate from B in Polar to C ((/41,41/),float) in Cartesian coordinates. Please help me. Any opinions are very grateful. Thank you very much.

Best wishes,

Tao Yang
            
             


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Received on Wed Jun 11 03:21:08 2014

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