Fig. 14From: A machine learning approach for mapping the very shallow theoretical geothermal potentialFourier analysis of a ground temperature time series example. The figure shows, for depth of 10 cm, in Bern, during the year 2013: (a) daily average temperature time series over the year, (b) and (d) amplitude and phase of the 30 first frequencies, (c) harmonics for the 3 dominant frequencies (here \(n=1\), \(n=4\) , and \(n=11\)) and resulting Fourier approximation of the signalBack to article page