一次多相态天气过程的风廓线雷达探测资料特征分析

A multi-phase weather process with fog, haze, rain and snow seen in Beijing on 17 March 2012 is analyzed by using wind profile radar data. The results show that the proliier products are good at diagno-sing and distinguishing weather change and evolution, and can reveal the detailed Variation ol precipitation. The proliier is usually used to detect weak horizontal wind and weak vertical movement ol atmosphere in case ol log. Its air relractive index is small while signal noise ratio (SNR) below 850 hPa is strong. Simul-taneously, the proliier Irequency spectrum shows the leatures ol clear weather. Belore it rains, the SNR in troposphere remarkably strengthens, the proliier vertical beam radial velocity (Vr) lirstly presents positive values, in the mid- and high-levels, which indicates the air sinking motion is enhanced. At the same time the other two double beams (V,.) are not symmetrical anymore. When it rains, all the live beams (V,) ol proliier turn positive Irom surlace to upper air, and the largest Vr is near surlace, not concentrated in the vertical beam. Correspondingly, spectrum width maintains in 1 — 2m· s_1. When precipitation phase changes, spectrum width diminishes obviously while SNR strengthens, and the V',. gets weakened. These changes usually occur in the whole boundary layer to troposphere. When rain stops, the above changes show reverse features, including spectrum width increases, SNR weakens, and all the five beams return to symmetrical State.