Fig. 2. Plots of the marginal effects of individual covariates in the GAM on daily tropospheric NO2 in Beijing.
a–h Covariates of qv, ua, va, temp, swdown, rain, dow, and daynum are shown in the panels. The EDF for the GAM smooth term is noted inside the bracket of the text. Each marginal effect is denoted by a solid line with a 95% confidence interval (dashed lines), and the vertical lines adjacent to the lower x-axis represent the distributions of these covariates