摘要
分析2011年6月27 ～ 28日大理地区入汛来首场强降水天气过程的影响系统、物理量特征以及风廓线雷达资料,结果表明此次区域性强降水过程的主要影响系统是东移的中纬度槽和低层的切变线;区域性强降水开始前,大理上空是不稳定能量的密集区且大气处层结于不稳定状态;从水汽条件看,过程开始前低层湿度虽大,但没有水汽的强辐合;强降水出现时存在剧烈的上升运动释放不稳定能量,且低层正涡度高层负涡度,散度场上低层辐合高层辐散,但低层辐合并不强;信噪比和垂直速度在降水的持续时间和降水强度方面与降水对应关系非常密切,强降水出现时间及持续时间与40 dbz高信噪比出现时间一致,垂直速度负值绝对值越大降水越强,厚度越厚持续时间越长;强降水出现时水平风随高度存在多层切变,强降水出现期间水平风矢量达到最高的位置,随着降水的减弱,测量到的水平风矢量高度明显降低.
The regular observation data and precipitation data by- hour of automatic meteorological station were used to analysis the impact system and physical characteristics of the synoptic process of Dali in Yunnan province w hich occur in 27Jun 2011 to 28Jun 2011. And the characteristic of w ind- profiling radar data of Dali national climate observatory w as analyzed before the heavy precipitation. It show ed that the mainly impact system of the regional heavy rainfall w as Eastw ard mid- latitude trough in 500hPa and shear line in 700hPa. Many physical characteristics w ere obvious before the heavy precipitation. It is energy- intensive areas over Dali and the atmospheric stratification is in unstable state before the heavy precipitation starts. Low- level moisture is great but the convergence of w ater vapor is not strong as usual before the heavy rain occurs in w ater vapor condition. When heavy rainfall occurs,there is intense upw ard motion w hich releases unstable energy. The vorticity field w hich low- level vorticity is positive and high- level is negative and the divergence field w hich low er level is convergence and higher level is divergence. But the convergence in low er level is not strong enough. There is a very close relationship betw een signal noise ratio of w ind profiler radar and heavy rainfall in rainfall duration and intensity of precipitation. So do as vertical velocity and heavy rainfall. Heavy precipitation occurrence and duration of the occurrence of high SNR w ith 40dbz is consistent. The negative absolute vertical velocity is greater w hen precipitation is stronger,thicker then the precipitation duration is longer. There is multi- level horizontal w ind shear w ith height before the onset of heavy rainfall. The horizontal w ind vector reaches the highest position during the heavy rainfall. Along w ith the w eakening of precipitation,height measured of horizontal w ind vector significantly reduces.
出处
《云南地理环境研究》
2013年第4期31-37,共7页
Yunnan Geographic Environment Research
基金
中国气象局面上项目"近地层通量观测资料的质量控制系统及其应用"(CMAGJ2011M43)
关键词
首场大雨
短时强降水
风廓线雷达
first regional heavy rain
short-term heavy rainfall
wind-profiling radar
