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    雷达定量降雪估测的不同方法准确性评估

    The accuracy of different methods for quantitative snowfall estimation based on radar

    • 摘要: 准确估测降雪量对天气预报、气候研究和水文管理具有重要意义,但是雪粒子尺度分布、密度及形状等特征存在高度异质性,使雷达降雪估测具有较大挑战。本研究基于奇台站双偏振雷达和地面气象观测站(站号:51379)观测数据,选取2022年至2024年间液态水当量大于1 mm的14个降雪个例,对8种基于雷达反射率因子Z估测降雪强度S的关系(缩写为S1-S8)在降雪量估测中的适用性和精度进行了评估。选取相关系数(CC)、平均绝对误差(MAE)、平均偏差误差(MBE)和均方根误差(RMSE)四种统计指标,对8种Z-S关系的整体估测效果以及在两个典型降雪个例中的性能进行了系统性分析。结果表明,S3(Z=120S^2)和S6(Z=40S^2)综合表现最佳。其中,针对2022年11月9日的估测结果,S3整体误差最小(MAE为8.1347,MBE为-1.3023,RMSE为10.7004)且与地面站点观测相关性较高(CC为0.9936);针对2023年1月11日的估测结果,S6虽然对强降雪存在高估现象(MBE值为0.2489),但整体误差最低(MAE为9.3978,RMSE为10.7111),适用性较强。因此,S3和S6在研究区降雪估测中适用性最高。本研究结果可以为Z-S关系优化和降雪量精确估测提供参考。

       

      Abstract: Accurate estimation of snowfall is crucial for weather forecasting, climate research, and hydrological management. However, the high variability in snow particles, including size distribution, density, and shape, pose significant challenges for radar-based snowfall estimation. This study evaluates the applicability and accuracy of eight radar reflectivity factor (Z)-snowfall intensity (S) relationships (abbreviated as S1-S8) for snowfall estimation using observation data from the Qitai Station dual-polarization radar and ground meteorological station (Station ID: 51379). Fourteen snowfall events with liquid water equivalent exceeding 1 mm between 2022 and 2024 were selected for analysis. Four statistical metrics—correlation coefficient (CC), mean absolute error (MAE), mean bias error (MBE), and root mean square error (RMSE)—were employed to systematically assess the overall performance of the eight Z-S relationships and their effectiveness in two typical snowfall cases. The results demonstrate that S3 (Z=120S2) and S6 (Z=40S2) exhibit the best overall performance. For the November 9, 2022 event, S3 achieved the smallest errors (MAE=8.1347, MBE=-1.3023, RMSE=10.7004) and the highest correlation with ground observations (CC=0.9936). For the January 11, 2023 event, S6 showed the lowest overall errors (MAE=9.3978, RMSE=10.7111) despite slight overestimation of heavy snowfall (MBE=0.2489). Consequently, S3 and S6 demonstrate superior applicability for snowfall estimation in the study area. These findings provide valuable insights for optimizing Z-S relationships and improving snowfall quantification accuracy.

       

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