Measurement Report: Lidar observations of Canadian wildfire smoke transported to East Asia in June 2025

Abstract. This paper provides a timely measurement report on the vertical structures and optical properties of Canadian wildfire smoke over East Asia based on lidar observations at Wuhan and Beijing, China in early summer 2025. Ground-based lidars detected smoke layers over Wuhan (30.5°N, 114.4°E) and Beijing (40.0°N, 116.3°E), China, during 16-18 June. In Wuhan, two stratospheric smoke layers appeared at 16.0-16.7 km and 17.2–18.3 km, with particle extinction coefficients of 25.8 Mm^–1 and 20.4 Mm^–1, raising stratospheric aerosol optical depth to 11.8 times the background level (0.052 versus 0.0044). The particle depolarization ratio (0.20) and lidar ratio (79±14 sr) at 532 nm indicate dominance of nonspherical, strongly absorptive smoke particles. In Beijing, a smoke layer appeared at 14.6–16.8 km, with a particle extinction coefficient of 47.7 Mm^–1 and PDR of 0.17. China's DQ-1 spaceborne lidar captured the smoke plumes over East Asia, with a north-south horizontal extent of ~2800 km. MODIS and OMPS observations identified potential wildfire source regions in Canada, while FLEXPART dispersion simulations with observationally constrained release conditions indicated plausible transport pathways through Europe to East Asia. Our lidar observations provides valuable insights into the long-range transport and optical properties of North American wildfire smoke over East Asia in summer 2025.