2009年天津地区首场降雪过程分析

Analysis of First Snowfall Process in 2009 in Tianjin

基于NCEP再分析资料、多普勒天气雷达产品与风云卫星云参数反演产品,对天津地区2009年的首场降雪过程进行了分析,研究表明:①造成此次降雪的主要天气系统是东移高空槽和地面倒槽;②降雪回波具备典型层云稳定性降水回波的特点,最强回波不超过35dBz,伴随着降雪结束,回波顶高有所下降;③降雪过程云粒子有效半径数值维持在20μm,云体过冷层厚度、云顶高度较大,云顶温度在-30℃左右。随着降雪结束,云粒子有效半径、云体过冷层厚度和云顶高度数值逐渐减小,云顶温度则有所升高;④地面降水量和云粒子有效半径、云顶高度、云体过冷层厚度呈现正相关,与云顶温度呈现负相关。

Based on the NCEP parameters, the first snowfall re-analysis data, Doppler Radar products and FY satellite retrieval cloud process of 2009 in Tianjin area is analyzed. The research shows that： （1） The main synoptic systems caused this snowfall process were the eastward-moving upper-level trough and the surface inverted trough. （2） The snowfall echo showed the typical characteristics of stratiform cloud precipitation, with the echo intensity not exceeding 35 dBz, and at the ending of snowfall process, the echo top height descended. （3） The cloud particle effective radius maintained around 20 /~m; during the snowfall process, the depth of supercooled cloud layer and cloud top height were larger, and the cloud top temperature was about --30 ℃ ; after the snowfall, the value of cloud particle effective radius, depth of supercooled cloud layer, and cloud top height decreased, while the value of cloud top temperature increased. （4） The correlativity between snowfall and cloud particle effective radius, depth of supercooled cloud layer, and cloud top height were positive, but that between cloud top temperature and snowfall was negative.