Analysis of Long-Term Trends in the Vertical Distribution and Transport Paths of Atmospheric Aerosols in Typical Regions of China Using 15 Years of CALIOP Data

Long-range transport and vertical distribution of aerosols are important factors for assessing the uncertainty in aerosol radiative forcing. This paper reveals the vertical distribution and trends of aerosol optical properties in China using 15 years of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data. The Hybrid Single-Particle Lagrangian integrated trajectory model was used to analyze the transport and trends of aerosols in the layer with the highest occurrence frequencies of dust, polluted dust, polluted continental and elevated smoke aerosols. The results indicated that (a) there were significant regional and seasonal differences in the vertical distribution of aerosols. The aerosol optical depth (AOD) trend in a given region depends on the changes in the aerosol type with the highest frequency and the layer corresponding to the largest AOD in the vertical profile. The frequency of polluted dust aerosols was the highest in Beijing-Tianjin-Hebei (BTH) and Central China. The considerable decrease in the 0-2 km AOD led to a significant trend of the column AOD. (b) The changes of AOD and main aerosol types in a region are also affected by the changes of aerosol sources and long-range transport pathways. In the BTH, dust aerosols originated from the Mongolian Plateau, accounting for 57.88% of the total trajectories. The Pearl River Delta was dominated by elevated smoke aerosols, with trajectories mainly originating from the Myanmar and Vietnam, accounting for 27.38% and 29.59%, respectively. The trend of 15-year backward trajectories of dust aerosols on the Tibetan Plateau indicated that the trajectory from India is increasing.

Automated summary

This paper uses 15 years of CALIOP data to reveal the vertical distribution and trends of aerosol optical properties in China. The results show significant regional and seasonal differences in the vertical distribution of aerosols, with polluted dust aerosols having the highest frequency in Beijing-Tianjin-Hebei and Central China. The changes in aerosols are influenced by sources and long-range transport pathways.