Modulation of Tropical Cyclogenesis over the South China Sea by ENSO Modoki During Boreal Summer

作     者：WANG Lei GUO Zhiliang 

作者机构：State Key Laboratory of Tropical OceanographySouth China Sea Institute of OceanologyChinese Academy of Sciences Department of Atmospheric Sciences School of Environmental Science and Engineering Sun Yat-sen University 

出 版 物：《Journal of Ocean University of China》 (中国海洋大学学报（英文版）)

年 卷 期：2014年第13卷第2期

页      面：223-235页

核心收录：

学科分类：07[理学] 070601[理学-气象学] 0706[理学-大气科学] 

基　　金：funded by the Strategic Priority Research Program of the Chinese Academy of Sciences with Grant No.XDA11010000 the National Natural Science Foundation of China (No.41205026) the National Basic Research Program of China (2011CB403500) the Innovation Group Program of State Key Laboratory of Tropical Oceanography (LTOZZ1201) Dr.Lei Wang was also sponsored by the Knowledge Innovation Program of the Chinese Academy of Sciences (SQ201208) the foundation for returned scholars of Ministry of Education of China the specialized research fund for the doctoral program of Higher Education for Youths the foundation of Guangdong Educational Committee for Youths (2012 LYM_0008) the open fund of the Key Laboratory of Ocean Circulation and Waves of Chinese Academy of Sciences (KLOCAW1309) 

主　　题：tropical cyclone South China Sea ENSO Modoki genesis potential index 

摘      要：This study examines the modulation of tropical cyclogenesis over the South China Sea （SCS） by the E1 Nifio-Southem Oscillation （ENSO） Modoki during the boreal summer. Results reveal that there were more tropical cyclones （TCs） formed over the SCS during central Pacific warming years and less TC frequency during central Pacific cooling years. How different environmental factors （including low-level relative vorticity, mid-level relative humidity, vertical wind shear, and potential intensity） contribute to this influence is investigated, using a genesis potential （GP） index developed by Emanuel and Nolan. Composite anomalies of the GP index are produced for central Pacific warming and cooling years separately, which could account for the changes of TC frequency over the SCS in different ENSO Modoki phases. The degree of contribution by each factor is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. The results suggest that the vertical wind shear and low-level relative vorticity, which are associated with the ENSO Modold-induced anomalous circulations in Matsuno-Gill patterns, make the largest contributions to the ENSO Modoki modulation of tropical cyclogenesis over the SCS as implied by the GP index. These results highlight the important roles of dynamic factors in the modulation of TC fre-quency over the SCS by the ENSO Modold during the boreal summer.