The investigations of the atmospheric precipitations by using Chung-Li VHF radar
The investigations of the atmospheric precipitations by using Chung-Li VHF radar
复制标题
中立VHF雷达大气降水调查
DOI：
10.1029/91rs00830
复制
发表时间：
1991
期刊：
影响因子：
--
通讯作者：
C. Liu
中科院分区：
文献类型：
--
作者：
Y. Chu;Lee;C. Liu
本文介绍了1988年6月2日台风苏珊过境台湾地区期间，中力VHF雷达的降水观测结果。我们发现VHF雷达不仅可以观测到雨滴的下落速度，而且可以探测到冰粒的下落速度。观测结果表明，前者约为6-8 m/s，后者约为1 m/s，与常规多普勒气象雷达观测结果一致。降水回波功率一般远小于大气活动波动回波功率。但在熔融层高度（台湾地区约5 km）处显著增强，其值可比大气放射性波动引起的值大约5dB。此外，还发现强亮带特征只出现在降水回波功率廓线中，而在大气降水活动回波功率廓线中则不能观察到强亮带。同时还分析了垂直和倾斜波束（天顶角为17°）的回波功率分布。结果表明，在降水环境中，大气环流活动起伏散射回波不存在方位敏感性。而降水回波功率在融化层以上存在方位敏感性特征，在融化层以下消失。水平风速与降水的多普勒谱宽有很高的相关性，相关系数为0.86。这表明水平风平流引起的波束展宽效应可能是影响降水谱宽的重要因素之一，在分析降水谱时应加以考虑。
In this paper the results of precipitation observed by Chung-Li VHF radar during the passage of typhoon Susan through the Taiwan area on June 2, 1988, are presented. We find that VHF radar can not only observe the falling speed of the rain drops but can also detect that of the ice particles. The observational results show that the former is about 6–8 m/s, while the latter is about 1 m/s, consistent with those observed by the conventional Doppler meteorological radar. The echo power due to precipitation is generally far smaller than that due to atmospheric refractivity fluctuations. However, it is enhanced strikingly at the height of melting layer (about 5 km in Taiwan area), and its value can be greater than that due to refractivity fluctuations by about 5 dB. Moreover, it also shows that the feature of bright band only occurs in the echo power profile of precipitation, and it cannot be observed in that of atmospheric refractivity. The echo power profiles of the vertical and oblique beams (with zenith angle 17°) are also examined. They indicate that there is no aspect sensitivity for the echoes scattered from the atmospheric refractivity fluctuations during the precipitating environment. However, for the echo power of precipitation the feature of aspect sensitivity does exist above the melting layer and disappears below this altitude. The correlation between the horizontal wind speed and the Doppler spectral width of precipitation is found to be fairly high, with a correlation coefficient of 0.86. This suggests that the beam-broadening effect due to the advection of horizontal wind may be one of the important factors contributed to the precipitation spectral width and has to be taken into consideration when the precipitation spectra are analyzed.