利用随机相位编码法恢复多普勒天气雷达二次回波

Recovery of Second-Trip Echo by Random Phase Coding in Doppler Weather Radar

多普勒速度对分析和预报强对流天气,特别是中尺度气旋、龙卷等过程至关重要,但受多普勒基本原理的限制,天气雷达在提高最大不模糊速度的同时,必然导致速度探测范围减小,进而带来二次甚至多次回波的干扰。为缓解多普勒两难问题,本文基于CINRAD/SA天气雷达体扫模式利用随机相位编码方法恢复二次回波,拓展速度有效探测范围。实例证明随机相位编码方法能够恢复最强的两次回波,滤除其他次弱回波,大大提高了低仰角速度场有效数据的获取率,缓解固定相位下二次回波解模糊算法的局限性造成的距离模糊紫区问题。

Doppler velocity is essential to analyze and forecast severe convective weather,especially mesocyclones and tornadoes.Doppler weather radar is restricted by Doppler dilemma,i.e.,when the unambiguous velocity increase,the corresponding unambiguous range decreases,and even worse for the secondary or more trips echo appear.To alleviate Doppler dilemma,this article uses the random phase coding technique to recover second trip echoes to expand the velocity detection range based on the current volume scan mode of CINRAD/SA weather radar.It proved that the random phase encoding can recover the second trip echoes and remove third and more trip echoes.It greatly improves the acquisition of velocity at low elevation and decreases the range ambiguous purple haze area caused by the limitation of velocity dealiasing algorithm without phase coding.