fft_spectrum

Function to plot the FFT power spectrum of continuous time-series data with time in days or datenum

This function makes spectral power density plots for continuous time-series data, for example oceanography data collected from moorings, hydrolab data from water quality studies or data sondes, or any continuous time series data set with equal time intervals in units of days and no missing data. If there are any missing data the missing values will be replaced with the mean of all the time-series data.

For example, to plot spectral density of time-series data for tide heights, dissolved oxygen, pH, temperature, salinity, etc.

The output from fft_spectrum is a figure and png file with two panels:

a. time series plot

b. plot of the FFT power spectrum of frequencies for the data

% load example data set of tide heights in Mar-Jun 2018 in Puget Sound
load fft_spectrum_example_data

% run the fft_spectrum function on the example data set
fft_spectrum(jdatenum, depth, 'Tide Height', 'm', 3);