Indirect evidence for elevated SO2 layers in the North China Plain

Wanyun Xu, Chinese Academy of Meteorological Sciences, State Key Laboratory of Severe Weather, Key Laboratory for Atmospheric Chemistry, Institute of Atmospheric Composition, Beijing, China, Chunsheng Zhao, Peking University, Beijing, China, Liang Ran, Key Laboratory of Middle Atmosphere and Global environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, Weili Lin, Meteorological Observation Center, China Meteorological Administration, Beijing, China, Peng Yan, Chinese Antarctic Center of Surveying and Mapping,Wuhan University, Wuhan, China and Xiaobin Xu, CAMS Chinese Academy of Meteorological Sciences, Beijing, China