辽宁“21·11”特大暴雪的双偏振雷达参量特征分析  

Analysis on parametric characteristics of dual polarization radar in the“21·11”extremely heavy snowstorm in Liaoning Province

作　　者：金巍[1,3] 胡志群 曲姝霖 于涵 李黎 JIN Wei;HU Zhiqun;QU Shulin;YU Han;LI Li(Anshan Meteorological Bureau,Anshan 114004,Liaoning,China;State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081,China;State Key Laboratory of Space Weather,Chinese Academy of Sciences,Beijing 100190,China;College of Atmospheric Sciences,Lanzhou University,Lanzhou 730000,China;Liaoyang Meteorological Bureau,Liaoyang 111000,Liaoning,China;Yingkou Meteorological Bureau,Yingkou 115000,Liaoning,China)

机构地区：[1]鞍山市气象局,辽宁鞍山114004 [2]中国气象科学院灾害天气国家重点实验室,北京100081 [3]中国科学院空间天气学国家重点实验室,北京100190 [4]兰州大学大气科学学院,甘肃兰州730000 [5]辽阳市气象局,辽宁辽阳111000 [6]营口市气象局,辽宁营口115000

出　　处：《冰川冻土》2023年第5期1575-1590,共16页Journal of Glaciology and Geocryology

基　　金：国家重点研发计划项目(2019YFC1510304);辽宁省气象局人才计划科技活动资助项目(RC202201);辽宁省气象局关键技术项目(LNGJ201901);空间天气学国家重点实验室2022年专项基金“地磁活动与大气环流变化的关联影响”资助。

摘　　要：2021年11月7—9日辽宁地区出现罕见特大暴雪过程(简称“21·11”特大暴雪),利用营口S波段双偏振雷达资料,分析不同降雪阶段的偏振参量特征差异,从中可以定性判断出过程的动力和微物理结构。强降雪时段(7日17:00—20:00,世界时)15 dBZ以上回波伸展到8 km附近,35 dBZ水平反射率因子(ZH)强度伸展到5 km以上,而且低层3 km高度以下点缀着40 dBZ以上的强反射率因子,说明本次高架对流降雪过程对流旺盛,空气中水汽条件深厚,容易形成较大直径与较高数浓度的雪花,产生强降雪;但是,差分反射率(ZDR)为-0.3~0.3 dB,高层和低层ZDR值均接近于0,下落的粒子形状近似圆球状,说明空中雪的粒子主要为小球形冰晶和雪花。在最强降雪时段,7 km高度的空中差分传播相移率(KDP)出现较大正值[≥0.3 (°)·km^(-1)],说明高空冰晶和雪粒子有较高的数浓度,可以用来预测降雪强度跃增。辽宁中部的强降雪粒子雷达特征为:在>2.0 mm小时强降雪估测中,ZH最大值和平均值分别为33~35 dBZ和21~26 dBZ,ZDR平均值和最大值分别为-0.3~-0.2 dB和0.3~0.8 dB,回波越强,反而ZDR越小,甚至为负值,说明强降雪过程中上升气流强,雪粒子主要以圆球状或竖椭圆状方式下落;在强降雪过程中,KDP最大值和平均值分别在0.2~0.4 (°)·km-1和0.1~0.2 (°)·km^(-1)之间,相关系数(CC)均大于0.98,说明强降雪时段雪花浓度更高,整个降雪过程雪花粒子相态的一致性较好,均以干雪为主。同时,ZDR偏振参量可以较好地识别干雪相态特征,双偏振雷达融化层(ML)和粒子分类(HCL)产品对降水粒子的判断有较好的实用价值。Based on the S-band dual polarization radar data in Yingkou,the microphysical characteristics of the polarimetric process of the rare heavy snow in Liaoning Province from November 7 to 8,2021 were analyzed.From the analysis of the radar vertical profile of the heavy snowfall center,it is concluded that the echo above 15 dBZ extends to about 8 km during the heavy snowfall period(17:00—20:00 on November 7,UT),and the hor⁃izontal reflectivity factor ZH of 35 dBZ extends to over 5 km.In addition,the lower layer below 3 km was dotted with strong reflectivity factors above 40 dBZ,which indicates that the snowfall process was characterized by strong convection,and the deeper the moisture condition in the air,the easier it was to form large-diameter snowflakes and produce strong snowfall.However,the differential reflectance(ZDR)ranges from-0.3 to 0.3 dB,with ZDR values close to 0 in both the upper and lower layers.The shape of the falling particles was ap⁃proximately spherical,indicating that the particles of snow in the air was mainly spherical ice crystals and snow⁃flakes in the air.KDP appears abnormal large value,the height reaches 7 km,which indicates that the concentra⁃tion of snowflakes increases obviously,and can be used to predict the jump of snowfall intensity.The micro⁃physical characteristics of heavy snowfall particle radar in the middle of Liaoning Province were as follows:The maximum and the average of ZH were 33~35 dBZ and 21~26 dBZ respectively in the estimation of heavy snowfall≥2 mm,and the average value and the maximum value of ZDR were-0.3~-0.2 dB and 0.3~0.8 dB,which indi⁃cated that the snowflakes section fell more vertically under the influence of updraft during the heavy snowfall,while the snowflakes section was more horizontal during the weak snowfall.The maximum and average values of KDP are 0.2~0.4(°)·km^(-1) and 0.1~0.2(°)·km^(-1) respectively,which indicates that the concentration of snow⁃flakes was higher and CC is higher than 0.98 during heavy snowfall,but the consiste

关 键 词：辽宁 暴雪 双偏振雷达 偏振参量 

分 类 号：P426.634[天文地球—大气科学及气象学]