Estimating spatio-temporal variability of aerosol pollution in Yunnan Province, China

Generally, areas with more anthropogenic emissions are more polluted. However, Yunnan Province, located in the southwest of China, has experienced serious aerosol pollution in recent years despite overall low anthropogenic emissions and high vegetation coverage. To explore the spatio-temporal variability of aerosol pollution in Yunnan, this study retrieved the near-surface PM2.5 and PM10 from 2017 to 2020 using random forest method based on Himawari-8 AOD data, and the influences of meteorological factors and terrain are also considered. The results show that aerosol pollution in Yunnan Province has significant spatio-temporal variety. Specifically, the annual average PM2.5 and PM10 of the whole province are 39.16 μg/m3 and 68.87 μg/m3 respectively, which are mainly contributed by the particulate matter in dry season (November to April), especially that in March and April. And PM distribution here differs greatly from north to south with 25° N as the boundary in dry season. From November to January, pollution level in the northern part is higher than that in the southern, while it is the opposite from February to April, which is mainly affected by the regional transport of pollutant, rather than the changes of local emissions or meteorological conditions.