中文摘要：

本文研究了多普勒天气雷达速度图上非降水回波（不包括地物回波）的空间结构,并对太原雷达站两年多以来的多普勒天气雷达观测到的“非降水回波”的速度特征进行了深入、系统的分析。发现非降水回波的强度虽然很弱,但其速度回波显示出冷暖平流和大尺度风向、风速辐合（散）相结合的特征。统计结果表明,56次降水过程中,有52次降水发生前的非降水回波具有辐合特征,且非降水回波辐合特征的出现较本站降水发生均具有一定的提前量,为临近预报提供了一种新思路。

英文摘要：

Spatial structure of non-precipitation echoes （not including clutter echoes） are deeply and systematically analyzed based on the Doppler weather radar data in Taiyuan. We find, though the intensity is very low , the non-precipitation echo velocity field shows the characteristic of superposition between large-scale wind speed and wind direction convergence（divergenc） and warm（cold） advection. The statistic results show the convergence characteristic of non-precipitation echoes before 52 precipitation processes in 56 precipitation processes . The generalization is 92.8 %. The convergence characteristic of non-precipitation echo velocity field appears ahead of precipitation processes about 5--7 hours. The results provide a new guidance for nowcasting.