CAJ | 학술논문

对降水云更高时、空分辨率观测资料的需求推动了天气雷达技术的发展，调频连续波雷达（FMCW）系统采用收发分置双天线体制，采用数字直接移相（DDS）技术和快速傅里叶变换（FFT）信号处理技术，获取高度分辨率达到15、30 m，探测周期2—3 s的回波功率谱分布和谱参数，具有脉冲多普勒雷达无法比拟的探测优势。C波段FMCW（C-FMCW）雷达最小可测信号功率达到－170 dBm，微弱信号的定量标校是技术难点。采用标准信号源输出单频信号，经过数字直接移相扩展为与雷达系统相同扫频范围信号，得到最小输入功率可达－169．77 dBm的定标曲线，由定量标校后的谱分布计算得到回波强度谱密度分布。该雷达于2013年6月起在安徽定远开始观测，利用8月24日降水过程探测数据，与距离该地48 km的蚌埠和83 km的合肥SA扫描雷达观测数据，分别进行对流云与层状云的观测比对分析。对于均匀分布的层状降水云，C-FMCW 雷达与SA雷达探测结果基本接近，C-FMCW雷达与蚌埠SA雷达的平均均方根误差为1．75 dB，与合肥SA雷达的平均均方根误差为2．02 dB，C-FMCW雷达与两部SA雷达探测的回波强度差异小于1 dB。对观测试验谱参数及回波强度谱密度分布进行了初步分析，C-F MC W雷达在研究降水云体的相态分区、晴空大气边界层回波等方面有较好的应用前景，有助于加深对强降水云中垂直运动的强烈变化的探测和认识。
대강수운경고시、공분변솔관측자료적수구추동료천기뢰체기술적발전，조빈련속파뢰체（FMCW）계통채용수발분치쌍천선체제，채용수자직접이상（DDS）기술화쾌속부리협변환（FFT）신호처리기술，획취고도분변솔체도15、30 m，탐측주기2—3 s적회파공솔보분포화보삼수，구유맥충다보륵뢰체무법비의적탐측우세。C파단FMCW（C-FMCW）뢰체최소가측신호공솔체도－170 dBm，미약신호적정량표교시기술난점。채용표준신호원수출단빈신호，경과수자직접이상확전위여뢰체계통상동소빈범위신호，득도최소수입공솔가체－169．77 dBm적정표곡선，유정량표교후적보분포계산득도회파강도보밀도분포。해뢰체우2013년6월기재안휘정원개시관측，이용8월24일강수과정탐측수거，여거리해지48 km적방부화83 km적합비SA소묘뢰체관측수거，분별진행대류운여층상운적관측비대분석。대우균균분포적층상강수운，C-FMCW 뢰체여SA뢰체탐측결과기본접근，C-FMCW뢰체여방부SA뢰체적평균균방근오차위1．75 dB，여합비SA뢰체적평균균방근오차위2．02 dB，C-FMCW뢰체여량부SA뢰체탐측적회파강도차이소우1 dB。대관측시험보삼수급회파강도보밀도분포진행료초보분석，C-F MC W뢰체재연구강수운체적상태분구、청공대기변계층회파등방면유교호적응용전경，유조우가심대강강수운중수직운동적강렬변화적탐측화인식。
The C-band Frequency Modulation Continuous Wave (C-FMCW)vertically pointing radar was developed with a new-ly signal processing technology.The C-FMCW radar uses the two-dimensional FFT signal processing technology,with the lowest detectable echo power of -170 dBm,and the quantitative calibration is difficult for weak signal.For a standard signal source analog echo point frequency,its frequency signal is able to be broadened to the signal with the same scanning range as the radar system,to get the calibration curve with the minimum input power up to -169.77 dBm,in which the calibration curve inflection point is able to confirm that the radar noise power is about -168 dBm.The spectral density of reflectivity can be computed from the spectrum of quantitative calibration.The data observed from the C-FMCW radar are compared with the SA scanning radar on Dingyuan,Anhui Province from June of 2013.The comparison analysis uses the data from the 48 km and 83 km CINRAD/SA Bengbu and Hefei radar,respectively,for the August 24 precipitation event.This event includes the two stages with convective cloud and stratiform cloud respectively.The reflectivity vertical distributions in the stratiform cloud for the C-FMCW radar and CINRAD/SA weather radar are basically in agreement,showing that the calculation of the C-FMCW radar system is reasonable.The average difference between the C-FMCW radar and SA radar in Bengbu in terms of the root mean square difference is 1.75 dB,and that between it and the Hefei SA radar is 2.02 dB.A preliminary analysis using the products and the spectral density of reflectivity,shows that the C-FMCW radar has a good prospect in the identification for the different particle phase thickness in precipitation cloud body,the study of echoes in the boundary layer of the clear atmosphere. And,it can also help to recognize the strong variations of vertical motion in the severe rain clouds.