基于螺旋度和非地转湿Q矢量的一次东移高原低涡强降水过程分析  

A Case Study of Plateau Vortex Moving East Ward with Heavy Rainfalls Based on Helicity and Non-Geostrophic Wet Q-Vector

作　　者：黄楚惠[1] 李国平[2] 

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

出　　处：《高原气象》2009年第2期319-326,共8页Plateau Meteorology

基　　金：国家自然科学基金项目(40875023);国家重点基础研究发展计划项目(2004CB418302)共同资助

摘　　要：利用NCEP 1°×1°再分析资料以及常规观测的地面和高空资料,应用螺旋度和非地转湿Q矢量原理,对2000年7月9～15日一例东移高原低涡产生强降水过程进行了天气动力学诊断分析。结果表明:500 hPaz-螺旋度水平分布对低涡中心的移动、降水落区和强降水中心的分布具有较好指示性,强降水中心发生在500 hPaz-螺旋度梯度值最大的区域。z-螺旋度分布能较好地反映暴雨发生时大气的动力学特征,暴雨区上空,高层负涡度辐散与低层正涡度辐合相配合,是触发暴雨的动力机制。相对螺旋度更能全面地反映降水落区及降水中心分布情况,并对未来6 h后的降水落区及走向具有较好的预报性,强降水中心发生在相对螺旋度正、负中心连线梯度最大值的正值一侧。低层非地转湿Q矢量散度的辐合区与降水区相对应,辐合中心与强降水中心基本吻合,是降水落区定性诊断分析的有力工具;湿Q矢量散度的垂直分布对未来6 h降水的落区和移动预报提供了很好的参考信息。Using NCEP global 1°×1° final-analysis data and the routine observation data, with the theories of helicity and non-geostrophic wet Q-vector, a case of Plateau vortex moving east which caused heavy precipitation was analyzed by both synoptic analysis and dynamic methods. The results show that 500 hPa horizontal distribution of z-helicity can give good direction to the movement of vortex center and distribution of rainfall, the heavy precipitation is located in the great grads of positive helicity, z--helicity can reflect the dynamic character of weather when the rainstorm occurred, and divergence of negative vorticity on higher level matched convergence of positive vorticity on lower level is a dynamic mechanism to trigger heavy precipitation. Relative spiral of more comprehensively reflect the rainfall districts and rainfall distribution center, and the next 6 h after the precipitation to the districts and have a better prediction of heavy precipitation occurred in a relatively central spiral of plus and minus centres connect the maximum gradient value of the positive side. Low level convergence of non-geostrophic wet Q-vector as a powerful tool to diagnose precipitation qualitatively has good relation to rain falls, convergence center are correlation with precipitation intensity; cross-section of wet Q-vector divergence provided good reference information for the distribution and movement of precipitation.

关 键 词：高原低涡 诊断分析 螺旋度 非地转湿Q矢量 

分 类 号：P458.121.1[天文地球—大气科学及气象学]