Three-dimensional distribution of dust aerosols over the Tarim Basin and the Tibet Plateau during 2007–2021 derived from CALIPSO lidar observations

Dust aerosols have been transported from the Tarim Basin (TB) to the Tibet Plateau (TP), which threatens the ecological security of the Asian water tower. However, the dust transportation process has not been understood fully so far. In this study, the three-dimensional (3D) distribution of dust aerosols over the TB and the TP was constructed and the transportation process was analyzed by utilizing Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite data. The meteorological background of one typical dust event was discussed and the trajectory of the pollutants was simulated by employing the fifth generation of the European Centre for Medium-Range Weather Forecasts reanalysis (ECMWF-ERA5) data and the Backward-trajectory Model. Besides, the importance of multiple natural factors was ranked using Random Forest Model. The results showed that dust aerosols were transported from the TB to the TP noticeably at 4–6 km above sea level, and 4 km above sea level was the dividing height of the dust transportation from the TB to the TP. Dust Aerosol Optical Depth (DAOD) value in the TB and the TP had significant monthly variations, which reached its highest in May and gradually declined. High frequency value of dust occurrence in the TB and the TP appeared in spring. There were always stable dust layers over the TB and the TP with an average thickness of about 0.64 km, which reached their thickest in spring. Furthermore, influenced by updrafts and prevailing westerlies, dust aerosols from the TB were carried to the northern slope of the TP and continued to be uplifted to higher than 6 km to its main body. Relative humidity and average wind speed could inhibit and promote regional air pollution respectively.