暴雨回波跟踪及临近预报初探

A PRELIMINARY STUDY ON THE ECHO TRACKING AND NOWCASTING OF RAINSTORMS

据数字化天气雷达测得的暴雨区PPI回波资料,滤去对降水影响不大的弱回波后,应用矩不变量法跟踪雨区中强回波块的移动;对两次冷锋型暴雨过程的试验结果表明,当雷达探测时间间隔分别为20和30min时,该法跟踪强回波块的平均准确率为91%。此外,还根据2幅和3幅PPI回波图象资料,在上述跟踪结果的基础上,试验线性外推等方法预报下一小时的强回波块落区,其结果也令人鼓舞。

Based on the PPI echo data obtained by digital weather radar in the rainstormarea and after filtering the weak echoes which have minor effects on the measurement ofrainfall,the movement of the strong echo blocks in the area is tracked by means of themoment invariant method. Results from the experiments on two cold-front heavy rainprocesses show that when the interval of radar detection is 20 or 30 minutes, the aver-age accuracy by this method reaches as high as 91%. In addition, on the basis of theabove experiment results and using two or three pictures in the PPI echo data, experi-ments are performed on the linear extrapolation method by which the locality of thestrong echo block in the next hour is forecasted. The results are rather inspiring.