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武汉X波段双偏振相控阵雷达定量降水估测产品质量评估

Quality Evaluation of Quantitative Precipitation Estimation Products from Wuhan’s X-band Dual-Polarization Phased-Array Radar

  • 摘要: 本文以实测地面降水数据为基准,选取2025年5—8月武汉8次典型的强降水过程,从降水总体识别能力、雨量等级敏感性、降水类型差异、时空分布特征、S与X波段雷达探测一致性五个方面,对武汉6部X波段双偏振相控阵雷达(X-band dual-polarization phased array radar,XPAR)组网的定量降水估测(Quantitative Precipitation Estimation,QPE)产品质量进行评估,以期为相控阵雷达QPE算法优化和业务应用提供科学依据。结果表明:QPE产品能较好识别地面降水,总体相关系数、平均偏差、相对平均偏差、均方根误差分别为0.93、-0.24%、-6.0%、2.88 mm。其中在小雨和中雨条件下降水识别准确率和估测量值可信度较高,随降水强度增加误差增大,在大雨及暴雨阶段估测误差较大且存在系统性低估。层状降水误差相对较小,对流降水和混合降水误差相对较大,暴雨强度条件下上述表现更为明显。QPE产品与实测降水在空间分布和时序变化的趋势一致,能有效反映降水过程的发生与演变,但降水估测性能在空间上表现出差异性。相控阵雷达QPE在刻画局地强降水细节方面相较于S 波段雷达具有更高的空间分辨能力。本文研究为X波段相控阵雷达QPE产品在气象预报业务上的应用价值提供了重要依据。

     

    Abstract: To provide a scientific basis for an optimized quantitative precipitation estimation (QPE) algorithm and operational application, this study evaluates the QPE product from a network of six X-band dual-polarization phased array radars (XPARs) in Wuhan, using rain gauge observations as ground truth. The assessment focuses on eight typical heavy-rainfall events from May to August 2025 and examines five key aspects: overall precipitation detection capability, sensitivity to rainfall intensity, differences across precipitation types, spatiotemporal distribution characteristics, and consistency between S-band and X-band radar observations. Results show that the QPE product effectively identifies surface precipitation, with an overall correlation coefficient, mean bias, relative mean bias, and root-mean-square error of 0.93, -0.24%, -6.0%, and 2.88 mm, respectively.The QPE product exhibits high accuracy and reliability for light-to-moderate rain, but performance degrades with increasing rain intensity, resulting in substantial errors and a systematic low bias during heavy precipitation events.Although stratiform precipitation is associated with smaller errors, convective and mixed types yield larger errors, particularly during rain storm.While the QPE product agrees with rain gauge observations in capturing the spatiotemporal evolution,its quantitative estimation performance exhibits spatial variability.Case comparisons reveal that the phased-array radar QPE provides finer spatial detail than the S-band radar in capturing the structure of localized heavy precipitation.This study demonstrates that the XPAR-network QPE product in Wuhan presents robust performance in depicting precipitation spatial patterns and tracking its temporal evolution, and exhibits significant application value in weather forecasting. However, it remains subject to systematic biases and spatial heterogeneities under varying rainfall intensities and in topographically blocked regions. This study provides an important basis for the application value of X-band phased array radar QPE products in meteorological forecasting operations.

     

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