sustainability Article Study of Persistent Pollution in Hefei during Winter Revealed by Ground-Based LiDAR and the CALIPSO Satellite Zhiyuan Fang 1,2,3, Hao Yang 1,2,3, Ye Cao 1,2,3, Kunming Xing 1,3, Dong Liu 1,3, Ming Zhao 1,3,* and Chenbo Xie 1,3,* 1 Key Laboratory of Atmospheric Optics, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;
[email protected] (Z.F.);
[email protected] (H.Y.);
[email protected] (Y.C.);
[email protected] (K.X.);
[email protected] (D.L.) 2 Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China 3 Advanced Laser Technology Laboratory of Anhui Province, Hefei 230037, China * Correspondence:
[email protected] (M.Z.);
[email protected] (C.X.); Tel.: +86-158-0091-7395 (M.Z.); +86-151-5597-3263 (C.X.) Abstract: LiDAR and CALIPSO satellites are effective tools for detecting air pollution, and by employing PM2.5 observation data, ground-based LiDAR measurements, CALIPSO satellite data, meteorological data, and back-trajectory analysis, we analyzed the process of pollution (moderate pollution, heavy pollution, excellent weather, and dust transmission weather) in Hefei, China from 24 to 27 January 2019 and analyzed the meteorological conditions and pollutants causing heavy pollution. Observation data from the ground station showed that the concentrations of PM10 and 3 PM2.5 increased significantly on 25 January; the maximum value of PM10 was 175 µg/m , and 3 the maximum value of PM2.5 was 170 µg/m .