0604号强热带风暴“碧利斯”特大暴雨的诊断研究

Diagnostic Analysis on Torrential Rain Caused by the Tropical Storm Billis(0604)

利用地面加密观测资料、自动站降水量资料和NCEP 1°×1°的每6 h再分析等资料,从能量、热量、水汽量以及环境场、冷空气和地形作用,分析了0604号强热带风暴"碧利斯"造成华南6省区大范围的强暴雨过程。结果表明:西太平洋副热带高压和大陆高压合并、西南季风异常活跃、高空强辐散流场和弱垂直切等均变有利于碧利斯陆上维持不消,越赤道气流致使西南季风强盛并将孟加拉湾和南海的水汽源源不断输入强暴雨区。分析发现:(1)风暴区域能量主要依靠潜热能平流的输送,维持暖性结构和产生强降雨;造成台风剧烈天气的动能是由非地转风穿越等压线,大气斜压性增强所制造的。(2)垂直输送项造成Q1和Q2的异常,是低层暖湿气流被抬升到高层产生凝结和潜热释放所造成的,积云对流所释放的凝结潜热对台风环流的反馈作用在台风暴雨中起到十分重要的作用。(3)冷空气从风暴东西两侧向低层嵌入,触发对流运动发展,近地层涡度和散度的形变项使山区处于一涡源状态,不断触发中尺度降水系统,促使暴雨增幅。

Based on the intensive observations, precipitation data of automatic observations and NCEP （1°×1°） 6 h reanalysis data, the study on the torrential rain caused by the Tropical Storm Billis （0604） was made through the analyses on energy, thermodynamics, vapor flux, synoptic circulation, cold air and terrain effect. The results show that the combination of west Pacific subtropical high and mainland high, extremely strong southwestern monsoon, intensive divergent stream filed in upper level and weak vertical shear jointly contributed to the persistence of Bills over land, and the southwest monsoon was strengthened by cross equatorial flow and transported the moisture in the Bay of Bengal and South China Sea into the rainfall area. Also the study arrived at some conclusions as follows： （1） The apparent heat energy was the main component part of the energy of Billis, the latent heat energy was second only to the apparent one at the low level of troposphere, but the potential energy takes the place of latent heat energy above the middle level of the troposphere. The maintenance of the total energy of the storm mainly depended on the advection of latent heat energy, which also contributed to the persistence of warm structure and the advent of torrential rain. The kinetic energy that caused the blustering weather of the storm was generated by the Ageostrophic wind, which crossed the isobar and intensified the baroclinicity of the air. （2） The local variation term was reverse to the advection term for both the apparent heat source （Q1） and moisture sink （Q2）. When warm and moist air at low level was lifted to higher level, the condensation of the moisture and the release of latent heat resulted ＂in the anomaly of Q1 and Q2 through vertical transportation term. The feedback from the latent heat associated with cumulus convection played a significant role in the torrential rain of typhoon. （3） The cold air invaded the lower level part of the storm from east and west sides, and triggered off the convection. The deformation term of the vorticity and divergence at atmospheric and surface level made the mountain area a vorticity source, where the mesoscale convective systems were constantly triggered off and the rainfall was increased.