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风廓线雷达回波信号强度定标方法
Calibration Method of Echo Intensity of Wind Profile Radar
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摘要: 风廓线雷达返回信号功率定标通常通过返回信号信噪比和系统噪声功率的估算得到。该方法存在着噪声电平的确定、外部噪声等不确定性因素，影响了定标的精度。采用信号源分别对接收机和信号处理器进行定量测试，进而对雷达系统进行定标，是另一种可行的办法，该文利用这种方法对CFL 03风廓线雷达进行了定标，并利用该雷达在东莞2009年7月和8月探测资料与广州S波段天气雷达和地面雨量计资料进行比较。结果表明：用该定标方法得到的回波强度与天气雷达回波强度和地面雨量计资料估算的回波强度基本一致，平均标准差在1 dB左右，表明这种定标方法是可行的。Abstract: A lot of researches about wind profile radar are based on analysis of echo power. So the estimation accuracy of echo power has direct effects on the use and expansion of wind profile radar data. At present, return signal power of wind profile radar is estimated by signal to noise ratio (SNR) and radar system noise power. Environmental noise may cause errors when estimating SNR in power spectrum of wind profile radar, affecting calibration accuracy. Another viable option is quantitatively testing the receiver and signal processor respectively using the same signal source, and then the calibration curve of radar systems can be determined according to the measured signal processor linear curve. Using this method, the calibration curve of CFL 03 wind profile radar is determined, and probe data of the radar in July and August, weather radar data and surface rain gauge data are compared. The results show that the weak signal of wind profile radar can be calibrated effectively, on the basis of measurement of the coherent accumulation and pulse compression accumulation using intermediate frequency source. The method proves feasible through the actual test. And through field experiments it can be seen that calibrated echo intensity of wind profile radar and SA weather radar echo intensity are basically the same with an average error less than 2 dB, within the scope of weather radar calibration error. The errors between calibrated echo intensity of wind profile radar and ground rain gauge data is less than 2 dB, indicating that the calibration results are credible.
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Key words:
- wind profile radar;
- calibration;
- noise level;
- SNR;
- return signal power
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图 4 广州SA天气雷达､东莞风廓线雷达与地面雨量计位置示意图
Fig. 4 Location diagram of Guangzhou SA weather radar and wind profile radar in Dongguan with the ground rain gauge
图 5 风廓线雷达与天气雷达回波强度随高度变化图 (a) 小雨, (b) 大雨
Fig. 5 Echo intensity of wind profile radar and weather radar (a) light rain, (b) heavy rain
表 1 相干积累得益检测
Table 1 Test of coherent accumulation
表 2 脉压积累得益检测
Table 2 est of pulse compression accumulation
表 3 东莞地区晴空等效大气返回信号回波强度随高度变化表（单位：dBZ）
Table 3 Echo intensity in sunny day in Dongguan (unit:dBZ)
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