Spatiotemporal variability and environmental factors of harmful algal blooms (HABs) over western Lake Erie - Fig 3

Wavelet power spectrum of the spatial average Chl-a concentration: (a) wavelet power spectrum of Chl-a, (b) global wavelet spectrum of Chl-a. The Chl-a series is from 5 January 2002 to 21 March 2012. The 5% significance level against red noise is shown as a thick contour. Outside the black cone contour is the region of the cone of influence (COI)–which is due to the finite length of the time series where the edge effects become important and distort the results.