北京首都国际机场冻雨过程的模拟及其产生的可能机制

为了探讨北京首都国际机场冻雨过程产生的可能机制，利用NCEP再分析资料、风云2号E星（FY-2E）的云顶亮温（Black Body Temperature，TBB）逐小时资料及风云3号A星（FY-3A）反演的云顶高度日平均资料做为检验依据，使用美国非静力中尺度模式（Weather Research and Forecasting，WRF）对2013年1月31日发生在首都机场附近地区的一次冻雨过程进行模拟，得出以下结论:1）模拟结果中的云顶温度与FY-2E的TBB逐小时资料对应较好:此次冻雨过程，整个降水云系云顶温度在0~-6℃之间，模拟结果水成物的垂直分布也得到了较好的印证；通过FY-3A反演的云顶高度日平均资料的检验，证明此次冻雨过程的云高基本维持在3 km左右，而且云微物理固态项的含量少。2）云顶温度、云顶高度实况与模式模拟表明此次过程是一次典型的暖雨机制冻雨，这说明产生北方冻雨的可能机制并不单一，冰相机制与暖雨机制可以同时存在。

Numerical Simulation of a Freezing-Rain Process in Beijing Capital International Airport and the Mechanism for Its Formation

In order to investigate the possible mechanism of freezing rain process, the WRF model (Weather Research and Forecasting) was used to simulate a freezing-rain process occurred on 31 Jan 2013 in the area of the Beijing Capital International Airport. The NECP reanalysis data, the Black Body Temperature (TBB) of FY-2E, the daily average cloud height data of FY-3A are used to verify the model simulation. Major conclusions are as follows:1) The cloud top temperature of the simulation is consistent with TBB of FY-2E. During the freezing rain process, the cloud top temperature varied between 0--6℃, and the simulated vertical distribution of the hydrometeors agree well with observations. According to the cloud top height derived from FY-3A observations, it is found that the cloud top in the freezing-rain process basically remained at around 3 km, and the clouds contained less microphysical solid contents. 2) Observed cloud top temperature and height and the simulation results show that this is a typical warm freezing rain process. This result indicates that the mechanism for the formation of freezing rain in northern China may not be single. Ice-crystal processes and warm-rain processes may simultaneously exist during the formation of freezing rain.