“07.08”陕西关中短历时强暴雨水汽条件分析  

Analysis on Water Vapor Condition of a Short-Time Heavy Rainstorm Process in Guanzhong,Shaanxi in August 2007

作　　者：慕建利[1] 李泽椿 赵琳娜[1] 陈雪珍 

机构地区：[1]中国气象局公共气象服务中心,北京100081 [2]国家气象中心,北京100081 [3]山西省运城气象局,山西运城044000

出　　处：《高原气象》2012年第4期1042-1052,共11页Plateau Meteorology

基　　金：北京局地暴雨中尺度对流系统研究项目(2010LASW-A05);GRAPES中尺度模式的预报和改进项目(GYHY201006016)共同资助

摘　　要：利用T213资料和地面逐时加密观测资料,对2007年8月8-9日陕西关中短历时强暴雨过程的水汽条件进行了详细的分析。结果表明,关中短历时强暴雨水汽来源于关中周围的高湿区,暴雨期间暴雨区上空水汽浅薄,地面至低层风向快速变化使暴雨区地面到低空湿度经历了减小—突然增加—快速减小的过程,水汽的聚集是通过偏东气流输送实现的,东西向水汽辐合是暴雨区水汽辐合的主要贡献者,北边界水汽的输入、输出和东边界水汽输入的突然增大、减小对暴雨的发生、发展及其结束有一定的指示意义;暴雨中心位于水汽通量大值中心及其下风向的水汽通量辐合中心之间;暴雨区可降水量的大小主要取决于水平水汽通量辐合的大小,水平水汽通量辐合的大小关键在于水平风场形成的辐合大小,而强降水的发生、加强、减弱及消亡与水汽的局地变化和水汽平流的变化关系更加紧密;近地层充足的水汽供应和水汽垂直输送形成的反环流圈使暴雨区水汽、能量迅速增加和抬升,建立了不稳定大气并触发能量释放,强降水开始;反之,形成暴雨的水汽条件不复存在,强降水结束。The water vapor condition of a stort-time heavy rainstorm in the Guanzhong, Shaanxi on 8-9 August 2007 was carefully analyzed using the T213 data and automatic meteorological observing data. The results indicate that the water vapor of heavy rainstorm is from a high humidity around the Guanzhong Shaanxi. Water vapor over the rainstorm area is shallow during the heavy rainstorm. Humidity change in rainstorm area has the process of ＇reduced--increases suddenly--reduces fast＇, because of wind direction fast change at the low level, and the vapor accumulation is obtained through the easterly current. The moisture convergence in the east-west direction is main contribution of convergence of vapor in the heavy rainstorm area. Occurring, intensification and weaken of heavy rainstorm had a close relationship with in- flow and outflow of moisture flux on the north boundary and sudden increase and decrease of vapor flux in- flow on the east boundary. The heavy rainstorm center locates in region between the maximum of water vapor flux and convergence center of vapor flux. The precipitable water in heavy rainstorm area primarily depends on the vapor flux convergence in horizontal direction, and vapor flux convergence largely is decid- ed in convergence of horizontal wind. The occurrence and weakening of severe precipitation have more clos- er relationship with the local change of water vapor and water vapor advection change. Anti-circulation cir- cle owing to the sufficient vapor supply at the surface layer and the water vapor vertical transportation cau ses rapid enhancement and lifting in the water vapor and energy, establishing the atmosphere of instability and triggering the energy release, which lead to formation of heavy rainstorm. On the contrary, vapor con- dition of formation rainstorm disappeared, severe precipitation end.

关 键 词：短历时强暴雨 水汽输送 水汽收支 反环流圈 

分 类 号：P458.121.1[天文地球—大气科学及气象学]