环境流场和“派比安”结构变化对其异常北抬路径影响的诊断分析

利用NCEP的全球数据同化系统(GDAS)1°×1°分析资料、CIMSS微波亮温资料等,对0606号台风派比安的异常移动路径特征作了诊断分析。结果表明:"派比安"出现的两次异常北抬路径与中纬度西风槽活动、热带西南季风、副热带高压以及热带气旋结构影响密切相关,西风槽槽后经向风活动和台风最大风速中心轴向对台风未来移向有一定的指示意义。     

台风杜鹃的特点及成因分析

台风杜鹃是继7908号台风后正面袭击珠江三角洲最强的台风，对其观测事实进行分析发现，台风杜鹃的路径和强度及其造成的天气分布等具有明显特点，这些特点与大气环流演变、影响台风的天气系统、相关物理量分布、“杜鹃”的结构及结构变化等密切相关。     

Synoptic Characteristics Related to Warm-Sector Torrential Rainfall Events in South China During the Annually First Rainy Season

Warm-sector torrential rainfall (WSTR) events that occur in the annually first rainy season in south China are characterized by high rainfall intensity and low radar echo centroids. To understand the synoptic characteristics related to these features, 16 WSTR events that occurred in 2013-2017 were examined with another 16 squall line (SL) events occurred during the same period as references. Composite analysis derived from ERA-Interim reanalysis data indicated the importance of the deep layer of warm and moist air for WSTR events. The most significant difference between WSTR and SL events lies in their low-level convergence and lifting; for WSTR events, the low-level convergence and lifting is much shallower with comparable or stronger intensity. The trumpet-shaped topography to the north of the WSTR centers is favorable for the development of such shallow convergences in WSTR events. Results in this study will provide references for future studies to improve the predictability of WSTR.     

粤东台风“浣熊”大暴雨的辐散风动能分析

利用热带气旋和雨量观测资料、NCEP再分析资料和辐散风动能方程,对台风"浣熊"在粤东造成大暴雨到特大暴雨的大尺度环流及动能转换特征进行了分析。结果表明,此次强降水过程主要是台风残涡与周围环境相互作用的结果。来自西太平洋的低层强偏东南急流和与热带气旋相连的西南急流,维持强水汽输送且输送至粤东地区;辐散风动能的变化对本次过程有较好的指示意义;低空两支急流的分布及辐合变化造成的动能通量辐合效应,是暴雨区辐散风动能的主要能量来源。此外,两支急流中心分别存在暖空气上升和冷空气下沉运动,斜压有效位能释放转化为辐散风动能。在上述两种过程中,冷空气均起到了重要作用。在低层近似辐合条件下,大气层结条件的不同是造成粤东和登陆点附近降水强度差异的重要原因。