Fig. 1. Effective reproduction number and mean temperature in the observation window for 409 cities.
Bivariate plot of effective reproduction number (Re) and mean temperature (Ta) (°C) in the observation window for each of the 409 study cities. Dark purple circles represent cities with both high Re and high Ta, while pale purple circles show areas with both low Re and low Ta. Red circles represent cities with low Re and high Ta and blue circles depict areas with high Re and low Ta. The bar chart (bottom right) represents the number of cities in each category defined in the bivariate legend (bottom left).