甘肃东部一次暴雪过程的诊断分析和数值模拟

应用NCEP1°×1°的6 h再分析资料和常规气象观测资料以及RUC模式高分辨资料,对2013年2月17日甘肃河东暴雪天气从天气实况、环流特征、水汽条件、动力条件及西北区域RUC模式输出的模拟结论进行了诊断分析。结果表明：高空冷槽、700 hPa低涡、地面冷锋是这次暴雪的主要影响系统;降雪前期,低层正涡度增强,低层辐合、高层辐散是暴雪发生的动力机制;降雪前期,由于低涡辐合作用,700 hPa高度以下,湿度猛增,为降雪提供了充沛的水汽条件;降雪中心和政上空有θse密集强能量锋区;西北区域RUC模式模拟的24 h内降水量范围、落区、量级与实况一致,模拟的地面风速偏大。

Numerical Simulation and Analysis of a Snowstorm Event in East Gansu Province

The circulation background and affecting system of a snowstorm event that occurred in east Gansu Province on Feburary 17 of2013 were analyzed firstly by using NCEP 6 hours reanalysis data,conventional observation data and high-resolution data of the RUC Model,and then the simulated result of the RUC Model was compared with the actual observation.The results show that the cold trough on the upper level,the low vortex on 700 hPa and the cold front on the ground were the main influencing system of this snowstorm event.Low-level convergence and high-level divergence resulted in strong upward movement in the middle-level,which provided beneficial dynamic conditions,and the water vapor convergence near the 700 hPa provided water vapour conditions.The intensive belt over Hezheng meant the high temperature and high humidity belt.The simulation results of the RUC Model were identical with the actual situation in snowstorm scope,snowstorm dropzone,but the simulated wind velocity on surface was larger than the actual one.