国家自然科学基金项目41571021,41171035;湖南省重点学科建设项目2016001;湖南重特大干旱机理研究项目2015001.National Natural Science Foundation of China,No.41571021 and 41171035;Construct Program of the Key Discipline in Hunan Province,No.2016001;The Research Project on the Mechanism of Extremely Severe Drought in Hunan Province,No.2015001.