【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。更多还原

【Abstract】 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 leve1 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.更多还原