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It seems that "periodogram" function can not give dominant period value directly. Can some functions give dominant period value directly? I want to find the significant (p<0.05) cycle of the sea surface temperature of each grid. I can use the power spectrum, and if there are other methods, it is also possible.

[,pxxc] = periodogram(,'ConfidenceLevel',probability) give the confidence level, but it seems that i must read it from figure. However, I want it output the period value, because I have many series. On the other hand, it seems effective to electrical signals, because it has remarkable period. But sea surface temperature has many periods, the figure can not show significant period.

This is from matlab help of function "periodogram". The lower confidence bound in the immediate vicinity of 100 and 150 Hz is significantly above the upper confidence bound outside the vicinity of 100 and 150 Hz.

This two figures are sea surface temperature series, can not find a significant period. It has dominate periods of 64, 28, 21.3, and 9 years enter image description here

Hao Wu
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  • probably something can be done with fft https://ch.mathworks.com/help/matlab/ref/fft.html?searchHighlight=fft&s_tid=srchtitle_fft_1 – Ferro Luca Jun 20 '23 at 06:06

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