凉山“8·31”致洪暴雨过程的中尺度诊断分析  

A Mesoscale Diagnostic Analysis in a Flood-Causing Torrential Rain Event in Liangshan Prefecture on Aug.31^(st),2012

作　　者：陈文龙 谌贵王旬 李文杰[3] 

机构地区：[1]凉山州气象台,四川西昌615000 [2]四川省气象台,四川成都610072 [3]成都信息工程学院大气科学学院,四川成都610225

出　　处：《成都信息工程学院学报》2013年第3期291-297,共7页Journal of Chengdu University of Information Technology

摘　　要：为了探索川西南山地大暴雨天气发生发展的机制,利用实况观测资料、NCEP再分析资料和卫星云图对2012年8月30～31日发生在凉山州北部的一次致洪局地大暴雨过程进行了中尺度诊断征分析。结果表明:此次局地大暴雨过程是在有利的环流背景下,由两高之间的切变和较强的西南低空急流共同作用产生的。暴雨区位于能量锋南侧,中低层不稳定能量丰富;垂直方向上相对涡度显著增大,低层辐合、高层辐散并伴随强烈的上升运动成为暴雨发生重要的动力条件;显著增大的水汽通量与强水汽辐合是大暴雨天气发生的重要水汽条件。MCS维持时间较长且稳定少动是导致暴雨的直接原因;近地层的中尺度辐合线是触发强对流的关键因子。Based on the routine observation data, NCEP reanalysis data and satellite cloud photographs, a torrential rain event causing a flood in the north of Liangshan Prefecture on Aug. 30^th to 3^st, 2012 is analyzed for finding out the development mechanism of torrential rain of the mountain area in the southwest of Sichuan Province. The results indicates that： due to the shear line between two high pressures and southwest low level jet, the torrential rain event occurs in a background of favorable circulation. The torrential rainfall area locates in the south of the energy front where instability energy is rich in middle and low level. The dynamic conditions are provided by significantly in- creased relative vorticity in vertical direction, and the configuration of convergence at low level and divergence at up- per level. The obvious increment of water vapor flux and intense water vapor convergence form the significant heavy rainfall conditions. The MCS that lasts for a long time and is almost motionless causes the rain storm weather direct- ly. Mesoscale convergence line at surface layer is a critical factor to trigger strong convection.

关 键 词：天气学 致洪暴雨 诊断分析 中尺度特征 水汽 辐合线 

分 类 号：P458.2[天文地球—大气科学及气象学]