上海浦东X波段双线偏振雷达衰减订正效果分析

Analysis of Attenuation Correction to an X-Band Dual-Polarization Doppler Weather Radar at Pudong,Shanghai

降水对X波段雷达电磁波的显著衰减,造成了回波弱化现象,带来了定量应用不准确的问题。为了减轻降水衰减对雷达数据的影响,用Z-K_(DP)(反射率因子-差分传播相位常数)方法对上海浦东气象局的X波段雷达反射率因子进行订正试验,具体方案为:当K_(DP)≥0.3°·km^(-1)时,用K_(DP)的值进行订正;当K_(DP)<0.3°·km^(-1)时,使用雨滴谱拟合A(衰减系数)和Z间的经验公式做衰减订正。选取对流性降水个例(2020年9月17日)和稳定性降水个例(2021年2月26日)进行衰减订正试验,经过衰减订正和系统偏差订正后,X波段雷达反射率因子与S波段雷达的反射率因子大小相当,回波形态相似,验证了该订正方法适用于对流性降水和稳定性降水的X波段雷达反射率因子的衰减订正。

Rainfall attenuation to X-band weather radar measurement is significant,and can lead to the weakening of radar reflectivity factor and inaccuracy in quantitative applications.By using the Z-K_(DP)correction method,the data collected by the X-band dual-polarization Doppler weather radar at Pudong,Shanghai were tested.The specific scheme is as follows.When K_(DP)≥0.3°·km^(-1),the value of K_(DP)is used to correct the attenuation;when K_(DP)<0.3°·km^(-1),the empirical formula between A and Z is used to correct the attenuation.The convective precipitation case(17 September 2020)and the stable precipitation case(26 February 2021)were selected for the test.After attenuation correction and system bias correction,the results show that both the value and the spatial distribution of the X-band’s radar reflectivity factor are close to that of the S-band weather radar.Such Z-K_(DP)method is effective to correct the attenuation from both convective rainfall and stable rainfall.