摘要
利用常规观测资料、NCEP再分析资料、卫星以及雷达资料对2015年8月16—18日影响川渝地区的一次持续性大暴雨过程进行了分析。结果表明:在亚洲中高纬和低纬相对稳定的环流背景下,两次高原涡东移、两次冷空气南下侵入四川盆地共同促进了西南低涡生成发展,造成此次大暴雨过程。西南低涡“初生形成”阶段,地面热低压东北侧有冷锋侵入,中心偏北形成暖锋,低涡近于正压;“稳定持续发展”阶段,冷锋南段移至地面热低压南侧,北段与暖锋结合形成准静止锋,低涡斜压性明显且呈近圆形,持续性暴雨主要出现在西南低涡的暖切变线附近和冷槽东侧;“东移变形减弱”阶段,冷空气第二次侵入,冷锋持续增强,西南低涡东移变形减弱。低层辐合、高层辐散、充沛的水汽输送以及不稳定能量的累积为西南低涡的加深、发展和强降水的维持提供了重要条件。西南低涡暖切变线和南侧冷槽附近发展起来的对流云团是暴雨产生的直接原因,强降水主要发生在云团上风方TBB梯度相对较大的区域。此次强降水过程的局地环流有低空急流和低空辐合线或切变线配合,雷达体积速度处理(velocity volume processing,VVP)法反演的风矢图可更直观地判断风向风速、天气系统所处的发展阶段以及判识辐合线或切变线,低空辐合线或切变线的演变以及低空急流的强度和移向对强降水天气产生的动力条件、维持时间和回波外推预报具有重要的指导意义。
Based on the conventional observation data,NCEP reanalysis data,satellite and Doppler radar data,a southwest vortex rainstorm process in Sichuan-Chongqing region from August 16 to 18 in 2015 was analyzed.The results indicate that the Tibetan Plateau vortices moving eastward and the cold air invading into Sichuan Basin contributed to the development of southwest vortex,and finally led to the heavy rainfall occurring under the relatively stable circulation background at middle-high latitude and low latitude in Asia.At the primary formation stage of southwest vortex,a cold front intruded on the northeast side of the surface thermal low pressure,a warm front formed on the north side of the center and the Southwest vortex was close to the positive pressure.At the stage of stable and sustainable development,the south part of the cold front moved to the south side of the low pressure,and the north part combined with the warm front to form a quasi-stationary front.The baroclinic property of the low vortex was obvious and nearly circular,and the continuous rainstorm mainly appeared near the warm shear line of the southwest vortex and the east side of the cold trough.At the weakening stage of southwest vortex moving eastward,the cold air invaded again,the cold front continued to strengthen,and the southwest vortex moving eastward deformed and weakened.The convergence at low-level,divergence at high-level,abundant water vapor transmission and accumulation of unstable energy played an important role in the deepening and development of southwest vortex and the maintenance of heavy precipitation.The convective clouds which developed near the warm shear line and the cold trough on the south side of low vortex led to the rainstorm.The heavy precipitation mainly occurred in the region with relatively large TBB gradient on the windward side of the cloud cluster.The local circulation of the heavy precipitation was composed of low level jet and shear lines or convergence lines.The wind vector of wind inversion based on VVP(velocity volume processing)could more intuitively judge wind direction and speed,development stage of weather system,convergence line and shear line.The evolution of low-altitude convergence line,shear line and the intensity and direction of low level jet had important guiding significance for the dynamic conditions,maintenance time and echo extrapolation prediction of heavy rainfall weather.
作者
高松
陈贵川
吴钲
杜钦
赵磊
呼延李豆
GAO Song;CHEN Guichuan;WU Zheng;DU Qin;ZHAO Lei;HUYAN Lidou(Chongqing Institute of Meteorological Sciences,Chongqing 401147,China)
出处
《干旱气象》
2019年第4期597-612,共16页
Journal of Arid Meteorology
基金
重庆市气象局青年基金项目(QNJJ-201702)
重庆市气象局智慧气象技术创新团队项目(ZHCXTD-201802)
重庆市气象局“十二五”重大建设项目“引进先进精细化业务系统”子项目“高性能计算机系统和数值预报系统”(2016-2019)共同资助
国家重点研发计划项目(2018YFC1507200)
关键词
西南低涡
高原涡
强降水
对流云团
VVP风场反演
southwest vortex
the Tibet Plateau vortices
heavy precipitation
convective clouds
wind inversion based on VVP(velocity volume processing)method
