2005年12月上旬山东半岛暴雪的观测与数值模拟研究

An Analysis and Numerical Modeling of a Snowstorm Event over Shandong Peninsula in December,2005

利用NCEP(National Centers for Environmental Prediction)的FNL(Final Analyses)资料、红外卫星图像、中分辨率成像光谱仪MODIS(Moderate-Resolution Imaging Spectrometer)图像以及位于烟台的Doppler雷达图像,对2005年12月3日～8日发生在山东半岛的暴雪进行了观测和数值模赔分析。天气形势分析表明:高空冷涡从西北方向持续不断地向山东半岛输送冷空气。此次暴雪过程中,渤海海水温度异常偏高,平均海温在11℃左右,远高于气候平均值8.2℃,表明渤海对过境冷空气的增温增湿作用是此次暴雪形成的重要原因,山东半岛的复杂地形对降雪带分布也有重要影响。降雪地点、持续时间、降雪量以及雪带方向等主要特征都被美国宾夕法尼亚州立大学和美国大气研究中心联合研制的中尺度模式(MM5)较好地模拟再现。模拟结果分析表明:此次暴雪过程属于浅对流过程,主要集中在对流层低部。

In this paper, a heavy snowstorm event that occurred over the east of Shandong Peninsula in December 2005 is investigated observationatly and numerically. The detailed evolutionary process of this event is documented by using almost all available observational data, such as Final Analysis （FNL） data provided by National Centers for Environmental Prediction （NCEP）, satellite infrared imagery, MODIS （Moderate-Resolution Imaging Spectrometer） images and Doppler radar data of Yatai station. The synoptic analysis indicated that there was continuous supply of cold air from the northwest direction toward Shandong Peninsula due to the existence of upper-level cold vortex. During the snowfall process, the sea surface temperature of the Bohai Sea was abnormally warmer than usual, and the mean sea surface temperature was around 11℃, which was greatly higher than the climatic value （8.2℃ ）. It suggested that the warming and moistening effects of the Bohai Sea upon the cold air-mass during its passage were regarded as the main influence factors of this heavy snowfall process. Complex topography of Shandong Peninsula had direct influence on the orientation and location of snowband. The main features of this snowstorm including duration, movement, location and orientation of snowband Were reasonably reproduced by the Pennsylvania State University-NOCAR Meso-scale Model version 5 （MM5V3.6）. Simulation results suggested that this snowstorm was a shallow convection process, and was only confined within the lower level of the atmosphere.