Xueying Liu¹, Amos P. K. Tai¹, Youfan Chen², Lin Zhang² and Gavin Shaddick³, (1)The Chinese University of Hong Kong, Graduate Division of Earth and Atmospheric Sciences, Hong Kong, Hong Kong, (2)Peking University, Department of Atmospheric and Oceanic Sciences, Beijing, China, (3)Department of Mathematics, University of Exeter, Exeter, United Kingdom