基金the support of the National Natural Science Foundation of China（Grant Nos.41375090 and 41375091）the Basic Research Fund of the Chinese Academy of Meteorological Sciences（Grant Nos.2013Z002 and 2015Z001）the support of a Direct Grant of the Chinese University of Hong Kong（Grant No.4052057）
基金Acknowledgements. The authors would like to thank the two anonymous reviewers for their helpful reviews that greatly improved the manuscript. This research is jointly supported by National Basic Research Program of China （Grant No. 2009CB421401）, National Key Technology R＆D Program （Grant No. 2009BAC51BO0）, and National Natural Science Foundation of China （Grant No. 40975022）.