降雹与不降雹冷涡过程的对比分析

The Comparision between the Processes of Upper Cold Vortex with Hail Shooting and Without Hail Shooting

该文通过对１９９６年６月１３日山东大范围冷涡降雹过程与同年６月２０日不降雹冷涡的对比分析指出：降雹与不降雹冷涡，除了冷涡北侧的高空形势有明显差异外，主要表现在低层的风场、温度场和层结稳定度有显著区别。当高空冷涡进入华北上空时，若北侧有高压脊向东北方向伸展，沿脊前有东北气流侵入冷涡后部。同时，低层在４０°Ｎ附近有明显的东西向锋区配合锋生变形场逼近鲁西北一带的潜在不稳定区，该冷涡会造成山东大范围降雹。而当高空冷涡发展为较对称的深厚气旋时，处于冷涡南侧的山东地区则不会出现强对流天气。

The comparison between the cold vortex with the large area hail shooting process on 13 June 1996 and that without hail shooting on 20 June 1996 was conducted.In addition to obvious difference of upper air circulation at north of the vortex,the significant differences in between were manifested on low level wind field,temperature field and stability.If the ridge of high at north of the cold vortex over north China is extending forward northeast,there will be a northeast flow entering the rear of vortex along the front of the ridge.Meanwhile in the low level there is a obvious east west frontal zone around 40°N with deformation field of frontogenesis,which approaching to the potential unstability area in northwest of Shandong province,the cold vortex will cause a large area hail shooting.Otherwise if the upper cold vortex developed into a symmetrical and deep cyclone,no hail shooting will occur in Shandong at the south of the cold vortex.