云南相邻C波段天气雷达与X波段天气雷达回波强度对比分析

Comparative Analysis of Echo Intensity Between Adjacent C-Band Weather Radar and X-Band Weather Radar in Yunnan

摘要:

近年来，云南省新建了多部X波段双偏振天气雷达，以补充新一代天气雷达观测网的探测盲区，提高全省雷达观测覆盖率。为了有效提高多体制雷达组网观测的准确性，选取2023年7月28日发生在昆明市和德宏州及其周边的强降水天气过程，以昆明、呈贡、德宏、盈江4部雷达同步观测体扫资料为例，通过对比不同时间和不同仰角组合的雷达回波强度，分析云南相邻C波段天气雷达与X波段天气雷达的回波强度一致性。结果表明：在同一观测区域、同一时刻，X波段天气雷达与C波段天气雷达均能正确反应降水的强弱变化，但回波强度测量值存在一定偏差，前者回波强度整体较后者偏大，因此往后需要进行统一系统标定和雷达回波强度衰减订正，提高雷达组网观测的准确性和一致性。

Abstract:

Because of its small size, low cost, perfect function, and stable performance, X-band weather radar provides fine observation data as a supplement for the new generation of weather radar in the low-level blind area, mountainous area, and key monitoring area. In recent years, Yunnan Province builds a number of X-band dual-polarisation weather radars to supplement the detection blind spots of the new generation of weather radar observation network and improve the coverage of radar observation in the province. In order to effectively improve the accuracy of multi-system radar network observation, the heavy rainfall weather process occurring in Kunming and Dehong Prefecture and their surrounding areas on 28 July 2023, is selected, and the data of synchronous observation bodies in Kunming, Chenggong, Dehong, and Yingjiang are taken as an example to compare the radar echo intensity of different time and elevation combinations. The consistency of echo intensity between adjacent C-band weather radar and X-band weather radar in Yunnan is analysed. The results show that both X-band weather radar and C-band weather radar can accurately reflect the intensity change of precipitation, but there is a certain deviation in the measured echo intensity; the former is larger than the latter. In the same observation area, the echo shapes of the two radars at different times and elevation angles are basically the same, and the echo generation, extinction, and change trend are consistent, correctly reflecting the intensity change of precipitation. The strong centre of the echo appears in the same position, but the strong centre of the X-band weather radar is more prominent. At the same time, the echo intensity of X-band weather radar is generally higher than that of C-band weather radar. The average echo value of Chenggong radar is 3.5 dBz higher than that of Kunming radar, and the maximum echo value is 15.5 dBz higher, and the average echo value of Yingjiang radar is about 5 dBz higher than that of Dehong radar, and the maximum echo value is 19.5 dBz higher. In the same observation area, C-band weather radar has more weak echoes, X-band weather radar has more strong echoes, and the peak echo intensity of X-band weather radar is greater than that of C-band weather radar. Comprehensive analysis shows that radar hardware difference, calibration inconsistency, beam blocking, altitude inconsistency, atmospheric attenuation, atmospheric environment difference, and so on are the factors that cause the echo intensity inconsistency between adjacent radars. Therefore, it is necessary to carry out unified system calibration and radar echo intensity attenuation correction to improve the accuracy and consistency of radar network observation.