铜仁一次暴雪过程多普勒天气雷达回波分析
Doppler Weather Radar Echo Characteristics of a Snowstorm in Tongren

针对2022年1月30~31日贵州铜仁暴雪天气过程，通过使用ERA5再分析数据、micaps地面填图数据、铜仁多普勒天气雷达数据等资料，分析此次过程中天气形势及雷达回波强度、径向速度、雷达垂直风廓线等产品的变化情况。结果表明：1) 本次暴雪过程受冷空气、500 hPa高空槽前西南气流、700 hPa急流及850 hPa偏东风和倒槽的共同影响；大气整层低于0℃、中层较强西南暖湿气流在强冷垫上爬升导致铜仁出现暴雪。2) 降雪过程中，最大反射率因子与小时降雪量有正相关关系，在降雪回波达到30~35 dBZ时降水量较大。由于冰晶、雪粒子反射率要小于雨滴粒子，所以出现40 dBZ以上的回波可能是雨夹雪或者雨。3) 降雪发展时，径向速度图上出现冷暖平流交汇、辐合特征加强，预示着本地区的降水强度加强，当暖平流明显减弱、辐合型风场减弱，降水强度也有所减弱。4) 风廓线产品反应了暖湿气流在冷垫上的爬升情况，也可以直观反应出垂直风切变情况，能较好反应降雪强度的增长趋势，同时也可以通过近地面层偏东风的厚度及风向随高度旋转程度判断冷空气的强度变化。
In response to the heavy snowfall weather process in Tongren, Guizhou on January 30~31, 2022, an analysis was conducted using ERA5 reanalysis data, micaps surface chart data, Tongren Doppler weather radar data, and other information to examine the weather situation and the variations in radar echo intensity, radial velocity, and radar vertical wind profiles during this event. The results indicate the following: 1) This heavy snowfall event in Tongren was influenced by cold air, southwest airflow ahead of the 500 hPa upper-level trough, a 700 hPa jet stream, and an eastward wind and inverted trough at 850 hPa. The presence of sub-zero temperatures throughout the atmos-phere and a strong southwest warm and moist airflow in the mid-levels ascending over a strong cold layer led to the occurrence of heavy snowfall in Tongren. 2) During the snowfall process, there was a positive correlation between the maximum reflectivity factor and hourly snowfall. Significant pre-cipitation occurred when the snowfall echo reached 30~35 dBZ. Due to the lower reflectivity of ice crystals and snow particles compared to raindrops, echoes above 40 dBZ may indicate a mix of rain and snow or rain. 3) As the snowfall developed, the presence of cold- warm advection convergence and enhanced convergence in the radial velocity field indicated an intensification of precipitation in the region. When the warm advection weakened and the convergence pattern weakened, the pre-cipitation intensity also decreased. 4) The wind profile product reflected the ascent of warm and moist airflow over the cold layer and provided an intuitive representation of vertical wind shear. It effectively indicated the increasing trend of snowfall intensity and could also be used to assess the strength of the cold air by analyzing the thickness of the near-surface easterly wind layer and the rotation of wind direction with height.