安徽省一次积层混合云增雨作业的综合效果评估
Comprehensive Effect Assessment of a Convective?Stratiform Mixed Cloud Precipitation Enhancement Operation in Anhui Province
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摘要: 本文使用安徽省国家级和区域级自动雨量站逐小时降雨量数据、安庆S波段雷达基数据和安庆探空等资料,对安徽省2023年6月17日一次积层混合云增雨作业进行了综合效果评估。结果显示,在播云后短时间内,观察到播撒高度上方1km范围内出现一狭窄的强回波区,播云后24min,强回波面积扩大,播撒高度处形成一强回波中心,回波形态由条带状变为团块状,强对流区集中。通过质心最优化匹配法和拉格朗日方法进行回波单元识别与追踪,并根据相似离度选取了最佳对比单元,进一步分析了作业单元与对比单元的5个雷达物理参量的时间序列变化。结果表明,作业单元的雷达物理参量值在作业后显著增加,并在42min内达到峰值并维持稳定,而对比单元的相应参量值则表现出下降趋势。双比分析显示,作业后1h内,5个参量的双比值均大于1,这表明对比单元强度逐渐减弱,而作业单元的生命周期得以延长且发展更为旺盛,作业效果显著。此外,本文采用基于聚类的浮动区域历史回归法优化了作业影响区自然降雨量的估计。首先使用K-Medoids聚类算法结合PCA降维技术对安徽省南部的降水特征进行了精确划分,接着通过交叉验证评估了六种回归模型的性能,结果表明ElasticNet回归模型在影响区的降雨量预测上表现最优,最后将回归模型应用于增雨个例,得到作业后3h绝对增雨量为2.92mm,相对增雨率为22.3%,单样本t检验结果显示,影响区的增雨效应在95%的置信水平下显著。Abstract: In this paper, a comprehensive effect assessment of a convective?stratiform mixed cloud precipitation enhancement operation in Anhui Province on June 17, 2023 was carried out using hourly rainfall data from national and regional automatic rainfall stations in Anhui Province, S-band radar data and sounding data in Anqing area. The results showed that shortly after cloud seeding, a narrow, intense echo area was observed within 1 km above the seeding height. This area expanded 24 minutes after the cloud seeding, formed an intense echo center at the seeding height. Additionally, the echo shape changed from strip to block, accompanied by a concentrated area of severe convection. The proper echo units were identified and tracked by the Centroid Optimization Matching method and the Lagrangian method, and the best comparison unit was selected based on the similarity measurement. Time-series variations of the five radar physical parameters of the seeded unit and the comparison unit were further analyzed. The results showed that following the operation, the radar physical parameter values of the seeded unit increased significantly, reaching their peaks within 42 minutes, and then remained stable. Conversely, the corresponding parameter values in the contrast unit exhibited a decreasing trend. The double-ratio values of the five radar physical parameters were greater than 1 within 1 h after the operation, indicating that the echo intensity of the contrast unit gradually decreased, while the seeded unit developed more vigorously with prolonged lifespan, demonstrating the obvious seeding effect. In addition, we optimized the estimation of natural rainfall in the operational impact area by using a cluster-based historical regression method for the floating area. Firstly, the K-Medoids clustering algorithm combined with PCA dimensionality reduction technology was used to accurately classify the precipitation characteristics in southern Anhui Province. Then the performances of six regression models were evaluated through cross-validation, and the results showed that the ElasticNet regression model had the best performance in predicting the rainfall in the area of influence. Finally, the regression model was applied in the individual cloud seeding case, providing the results of 2.92mm rainfall increase in 3h after operation and 22.3% rainfall enhancement effect, the results of the one-sample t-test showed that the precipitation enhancement effect in the affected area was significant at the 95% confidence level.