北京一次强单体雹暴的三维数值模拟

Three-Dimensional Numerical Simulation of a Strong Convective Storm in Beijing

利用中国科学院大气物理研究所建立的完全弹性三维雹云数值模式 ,模拟了1 996年 6月 2 9日发生在北京东北部京冀交界地区的一次强单体雹暴过程 ,并结合多普勒雷达探测资料 ,分析了风暴的流场结构、雷达回波结构特征、含水量场等宏微观物理量的分布及其演变。模式模拟出了超级单体风暴云的一些典型特征 ,如悬垂回波、弱回波区、回波墙等。同时 ,模拟分析了冰雹形成的微物理过程 ,结果表明 ,本个例模拟雹云中 ,冰雹粒子主要由冻滴 (CNfh)和霰 (CNgh)转化形成 ,但冻滴对冰雹形成的贡献比霰大得多 ,冰雹含水量中心的发展演变与冻滴含水量中心的发展演变相一致 ,冰雹主要是通过撞冻过冷水过程 (CLch、CLrh)而进一步长大的。

The fully elastic three dimensional convective storm model (IAP CSM3D) developed by the Institute of Atmospheric Physics (IAP), the Chinese Academy of Sciences was used to simulate a strong convective storm that occurred in the northeast of Beijing on June 29, 1996. The initial field of the model is the in situ observational data. Combining the observational data by the Doppler weather radar, the distribution and evolution of macro physical as well as micro-physical variations such as wind field structure, radar echo structure, overhang echo, bound weak echo region, strong echo wall, water content, etc. in the storm were analyzed. Some typical features of supercell structure were revealed on the basis of the analysis. The formation mechanism of hailstones in the storm was analyzed too. The results show that the auto conversion of frozen drops and graupels (CNfh, CNgh) are the main sources of the hailstones in the strong convective storm studied in the paper, but the contribution of frozen drops is greater than that of graupels. Hailstones mainly depend on the processes of collecting supercooled water (CLch,CLrh) to grow.