Di Zhao, Kunming, Yunnan, China, Ruowen Yang, Yun Tao, Meteorological Institute of Yunnan Province, Kunming, China, Weikang Zhang, Doumen County Meteorological Bureau of Guangdong Province, Zhuhai, China and Xucheng He, University of Helsinki, Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, Helsinki, Finland