摘要
本文利用六部激光雨滴谱仪与两部S波段双偏振雷达观测数据,分析了浙北地区2022年3—10月暖季降水微物理特征,并评估了雷达反演体积中值直径D 0和截距参数N w的精度。结果表明:①浙北降雨D 0和N w均值分别为1.0 mm和104.3 m^(-3)·mm^(-1),呈现以高浓度小雨滴为主的暖云降水特征。基于降雨率R均值与标准差可有效区分层状云(雨滴谱窄,R<10 mm·h^(-1),D 0<1.0 mm)和对流云(雨滴谱拓宽,R和D 0均值分别为19 mm·h^(-1)和1.8 mm)降水。②T矩阵散射模拟的S波段雷达参量(反射率Z、水平反射率Z h、差分反射率Z DR和差分传播相移率K dp)与实际观测一致,验证了散射模型的适用性,并构建了D 0(Z DR)和D 0(Z h/N w)的反演关系,二者的理论反演偏差分别为-0.005 mm和0.029 mm。③六次降雨过程检验反演关系精度表明嘉兴S波段双偏振雷达对D 0和N w(相关系数0.536,偏差-0.395 m^(-3)·mm^(-1),均方根误差0.819 mm)的反演精度均优于杭州S波段双偏振雷达。本研究为浙江地区双偏振雷达反演降水微物理参数提供了科学依据,未来需进一步优化模型以提升反演精度。
This study systematically investigates the microphysical characteristics of warm-season precipitation over northern Zhejiang Province,China,based on comprehensive observations from six laser precipitation monitors(LPMs)and two S-band dual-polarisation weather radars(HZ-SPOL and JX-SPOL)collected between March and October 2022.In addition,the performance of dual-polarisation radar retrievals of raindrop size distribution(DSD)parameters,specifically the mass-weighted mean diameter(D 0)and the normalised intercept parameter(N w)of the gamma distribution,is quantitatively evaluated.The results reveal the following:(1)Precipitation in the northern Zhejiang region is predominantly characterised by high concentrations of small raindrops,with an average D 0 of 1.0 mm and a mean N w of 104.3 m^(-3)·mm^(-1),exhibiting typical features of warm-cloud precipitation.A classification approach based on the statistical properties(mean and standard deviation)of rainfall rate effectively discriminates between stratiform and convective precipitation.Stratiform precipitation shows relatively narrow DSDs and low spatial variability across sites,with low rainfall intensity(R<10 mm·h-1)and smaller drop sizes(D 0<1.0 mm).In contrast,convective precipitation exhibits significantly broader spectra,with D 0 and average R values reaching up to 1.8 mm and 19 mm·h-1,respectively,and displays much greater spatial heterogeneity.Medium-sized raindrops(1.0-2.0 mm)contribute the largest fraction(33.4%)to total rainfall accumulation,while larger drops(D 0>2.5 mm),though relatively infrequent,still account for 10.3%of total rainfall volume.(2)Simulated polarimetric variables at S-band—reflectivity(Z),differential reflectivity(Z DR),and specific differential phase(K dp)—calculated using a T-matrix scattering model based on local DSDs,show good agreement with actual radar observations,validating the applicability and robustness of the scattering model in the region.Retrieval relationships for D 0 and N w are established using the localised DSD dataset.Sensitivity analysis indicates that D 0 is primarily influenced by Z DR,with a negligible bias of-0.005 mm,while N w is influenced by both Z and Z DR and exhibits larger variability,with a mean bias of 0.029 m^(-3)·mm^(-1).(3)Validation is carried out using six precipitation events observed at Changxing in 2023,comparing retrievals from two radars:Jiaxing(JX-SPOL)and Hangzhou(HZ-SPOL).The JX-SPOL retrievals of D 0 show better agreement with LPM measurements,with a mean bias of 0.087 mm and RMSE of 0.418 mm,outperforming HZ-SPOL(bias-0.195 mm,RMSE 0.444 mm).For N w,JX-SPOL yields a higher correlation coefficient(0.536)compared to HZ-SPOL(0.199),and the absolute deviation and RMSE(HZ-SPOL 1.046 m^(-3)·mm^(-1) and JX-SPOL 0.819 m-3·mm-1)are relatively close,although systematic biases remain:JX-SPOL tends to underestimate by 0.395 m^(-3)·mm^(-1),whereas HZ-SPOL overestimates by 0.494 m^(-3)·mm^(-1).Overall,this study provides a scientific basis for improving dual-polarisation radar retrievals of precipitation microphysics in Zhejiang Province.The findings highlight the importance of localised DSD datasets in optimising retrieval algorithms and emphasise the need for further validation efforts using diverse precipitation events and multi-site observations to enhance the accuracy,stability,and generalisability of radar-based microphysical retrieval techniques.
作者
陈昊
罗丽
陈亮
汪章维
崔雪东
王晗
沈吉
CHEN Hao;LUO Li;CHEN Liang;WANG Zhangwei;CUI Xuedong;WANG Han;SHEN Ji(Zhejiang Atmosphere Observation Technical Support Centre,Hangzhou 310018;Beijing Institute of Urban Meteorology,CMA,Beijing 100089;Zhejiang Meteorological Safety Technology Centre,Hangzhou 310052)
出处
《气象科技》
2025年第5期719-737,共19页
Meteorological Science and Technology
基金
中国气象局气象能力提升联合研究专项(22NLTSY007)
浙江省自然科学基金联合基金资助项目(LZJMZ24D050009)
浙江省科技厅重大社会公益专项(2022C03150)资助。
关键词
降水微物理特征
雨滴谱仪
S波段双偏振雷达
雷达反演精度
precipitation microphysical characteristic
disdrometer
S-band dual-polarisation radar
retrieval accuracy of polarimetric radar
