Tracing smoke layers to the Arctic: insights from five years of CALIPSO observations

Abstract This study provides a comprehensive multi-year assessment of Arctic and Boreal smoke transport using spaceborne lidar observations in combination with atmospheric trajectories, fire injection heights, and satellite-based land-cover data. Our results demonstrate that smoke layers in the Arctic region exhibit consistent geometrical properties regardless of their source regions in Asia, Europe, or North America, likely due to similar land-cover types across these boreal source regions. Approximately 91% of the smoke layers observed over the Arctic originated from long-range transport from lower latitudes, indicating that a significant portion of boreal smoke is advected northward into the Arctic region. Although local Arctic fires contribute less to the atmospheric smoke load in the region, the average aerosol optical depth (AOD) and layer mass of local smoke layers were marginally higher compared to the long-range transported smoke, signaling the rapid development in this part of the world. Smoke aerosol layers originating from Siberian fires were the dominant contributor to the total smoke mass estimated in the Arctic region from 2018 to 2022. Our comparison of CALIOP-derived smoke mass with MERRA-2-simulated organic and black carbon mass shows strong summertime consistency but a systematic bias and substantial divergence outside the fire season.