Characteristics and variations of the East Asian monsoon system and its impacts on climate disasters in China

Recent advances in studies of the structural characteristics and temporal-spatial variations of the East Asian monsoon (EAM) system and the impact of this system on severe climate disasters in China are reviewed.Previous studies have improved our understanding of the basic characteristics of horizontal and vertical structures and the annual cycle of the EAM system and the water vapor transports in the EAM region.Many studies have shown that the EAM system is a relatively independent subsystem of the AsianAnstralian monsoon system,and that there exists an obvious quasi-biennial oscillation with a meridional tripole pattern distribution in the interannual variations of the EAM system.Further analyses of the basic phvsical processes,both internal and external,that influence the variability of the EAM system indicate that the EAM systern may be viewed as an atmosphere-ocean-land coupled system,referred to the EAM climate system in this paper.Further,the paper discusses how the interaction and relationships among various components of this system can be described through the East Asia Pacific (EAP) teleconnection pattern and the teleconnection pattern of meridional upper-tropospheric wind anomalies along the westerly jet over East Asia.Such reasoning suggests that the occurrence of severe floods in the Yangtze and Huaihe River valleys and prolonged droughts in North China are linked,respectively,to the background interannual and interdecadal variability of the EAM climate system.Besides,outstanding scientific issues related to the EAM system and its impact on climate disasters in China are also discussed.