Detection of Tonga Volcanic Ash Using Middle and Upper Atmospheric Lidar

This study presents the first report of detecting Tonga volcanic ash over Wuhan (30.5°N, 114.3°E) using a middle and upper atmospheric lidar system. The research analyzes the intensity variations of Tonga volcanic ash as it spread over Wuhan from March to July 2022, and also examines the volcanic ash's Aerosol Index (AI). The findings reveal that from March 8 to 7 April 2022, the detected volcanic ash signals were relatively weak. However, starting on April 10, 2022, the lidar detected a sudden increase in the strength of the volcanic ash return signals, which remained consistently strong between altitudes of 20～25 km over the following months. This phenomenon suggests a significant change in the volcanic ash's propagation during this period, which may be closely related to atmospheric flow patterns. Further analysis of the detected volcanic ash heights revealed an uneven, layered structure in the stratosphere, indicating a distinct distribution of volcanic ash at different altitudes. This provides important insights into the mechanisms of volcanic ash propagation in the atmosphere and its environmental impact. Additionally, the lidar data analysis from April to July 2022 shows a weak correlation between the detected volcanic ash altitude and the particle size. This suggests that the movement and settling behavior of volcanic ash particles are likely influenced by various complex factors, rather than being governed solely by their size.