西北太平洋热带气旋残留低压对中国大陆地区降水的影响

西北太平洋热带气旋(TC)是影响中国降水的重要天气系统,其减弱后的残留低压(TCRL)仍然携带大量的水汽和能量,给其经过之处带来强降水。为分析热带气旋残留低压对中国降水的影响,采用客观方法从ERA-40和ERA-Interim再分析资料中识别出热带气旋对应的气旋,从而得到热带气旋残留低压活动资料。将残留低压的活动路径分为东北路径、东南沿海路径和西行路径3类,采用客观天气图分析法(OSAT)得到残留低压影响下的降水分布,对残留低压的活动路径和降水的分析结果表明,文中采用的方法能追踪得到热带气旋的完整生命史,在1958-2014年进入警戒区的718个热带气旋中,追踪得到706个对应的气旋,追踪的气旋中心与热带气旋中心平均距离131 km;共443个热带气旋有对应的残留低压,平均持续时间48.5 h,1 d以上的残留低压共293个,占66.1%,残留低压的持续时间与对应的热带气旋强度没有显著的关系,夏季残留低压持续时间较冬季长;对内陆地区的影响残留低压较热带气旋更为显著,降水影响自东南向西北减少,影响范围较热带气旋西扩,强度更大;东北路径主要进入地区为东北和华东地区,影响中国东部地区的降水;东南沿海路径影响范围最广,影响降水的强度最大;西行路径进入范围仅华南和西南地区,主要影响中国南部地区的降水,降水强度最小。 

Activity characteristics of remnant lows of tropical cyclones of the western North Pacific and its impact on precipitation of China mainland

The western North Pacific tropical cyclone (TC) is one of the most significant weather systems affecting precipitation of China. The TC remnant low pressure systems (TCRL) still carry abundant moisture and energy, causing heavy rainfall along the TCRL's track. In order to analyze the impact of TCRL to precipitation of China, the objective methods were applied to identify TC cyclones based on the ERA-40 and ERA-Interim reanalysis, and thus obtain the TCRL tracks. The tracks of TCRL were classified to 3 categories, they were the Northeastward one (NE), Southeastern coast one (SEC) and Westward one (WW). TCRL effected precipitation distribution was obtained with the objective synoptic analysis technique (OSAT). Using this technique, we could track whole life history of TCs. There were 706 cyclones in total tracked from the 718 TCs that entered into the warning region during 1958-2014, and the average distance between the cyclone center and the TC center is 131 km. A total of 443 TCs had corresponding TCRLs which sustained for 48.5 hours on average, among which 293 TCRLs' lifetime lasted more than 1 day, to account for 66.1%. TCRLs' duration had no significant relationship with TCs' intensity. Lifetime of the TCRLs in summer was longer than that in winter. The influence to China inland of TCRLs was more obvious than TCs. TCRLs, whose influence range is larger than that of TC, brought more precipitation in southeastern China, and less precipitation in northwestern China. NE TCRLs entered the area of northeastern and eastern China, bringing precipitation mainly in eastern China. SEC TCRLs' influence was the widest, bringing the strongest precipitation. WW TCRLs entered only southern and southwestern China, bringing the weakest precipitation mainly in southern China.