Figure 3
Visibility-based hygroscopic growth factor, i.e., \(f\left( {RH} \right)\), of PM2.5 for the ICN data set in 2019, calculated by (a) observed and (b) modeled visibility, as a function of relative humidity (RH). Red circles: PM2.5 concentrations in the range of 22–32 μg m−3; green triangles: PM2.5 range of 32–42 μg m−3; blue crosses: PM2.5 range of 42–53 μg m−3. The mean and 97.5th of PM2.5 concentrations are indicated by 22 and 53 μg m−3, respectively. The modeled visibility was induced by Model 2 (Table S-2).
