Fig 1. Parameter estimation for the generalized radiation model.

In the top panels, we vary the scaling exponent λ for each model, and compute the Sørensen-Dice similarity between the model output and the real data. The λ yielding the peak similarity value is the estimated parameter of the adopted model. In the middle panels, the Pearson Correlation Coefficient (PCC) is calculated between the model output and the real data. In the bottom panels, the correct normalization factor κ is derived for models with different scaling exponents. Note that the estimated scaling exponent λ is 1.0, 0.3, 0.4, 0.6, 0.8, 0.2 for US, UK, Beijing, Shenzhen, Abidjan and Chicago, respectively.