Fig. 3
Observed (grey bars) and predicted (red lines) Austrian tick-borne encephalitis series (left) and corresponding power spectra (right). GLM1: model using exclusively the human population NTOT as predictor variable resulting in a good approximation of the linear trend depicted by the black line. GLM2: model extended by the predictors net migration rate NMIG and Scandinavian index SI to explain low-frequency oscillations. GLM3: model extended by the beech fructification index 2 years prior Fyear−2 to explain also high-frequency oscillations. GLM4: best performance model extended by the annual sunshine duration SD. For each model the verification measures root-mean-square error (RMSE) and explained variance R2 (with R\(^{2}_{{adj}}\) in brackets) are given. Period 1979–2018