宁夏北部强降雪天气的非地转湿Q矢量的诊断

为了有效利用数值预报产品,提高中尺度数值预报模式MM5的释用能力,做好灾害性天气的预报,引用非地转湿Q矢量理论对2006年1月18-19日宁夏北部一次强降雪过程进行了诊断分析.结果表明:500hPa西风槽、700hPa偏南风低空急流、地面倒槽、冷锋是这次宁夏大范围降雪的主要影响系统;非地转湿Q矢量流场辐合中心和宁夏北部强降水中心有很好的对应关系;锋生函数的正大值与强降水中心对应较好,可以认为对宁夏冬季强降水中心有一定的指示意义;最强降雪区出现在Q矢量散度正负值交界附近的负值区上升支一侧.

Non-geostrophic wet Q-vector diagnostic analysis of a snow-storm in the north part of Ningxia

In order to use numerical predictive products effectively,to enhance the ability of explaining middle-scale numerical predictive(MM5)model, and improe short-term disaster weather forecast,a diagnosis of a heavy snow-storm from Jan.18 to Jan.19,2006 was made with the non-geostrophic wet Q-vector theory.The results show that the short wave trough at the 500 hPa,southly jet at the 700 hPa,converse trough,and cold front on the surface are the influencing systems.The region of heavy snow-storm has a good relation with Q divergence center or line.The region-magnitudes of Q frontogenesis function could be used to locate the snowfall area.The conclusion is that according to the positive big value area of the frontogenesis function the most heavy snowfall comes forth when the non-geostrophic wet Q-vector divergence positive minus value is at the side of rise.