宁夏一次寒潮的天气学预报与数值模式预报对比分析

Comparative analysis on synoptic and numerical forecasting of a cold wave process in Ningxia

2008年12月21日前后宁夏出现一次寒潮天气过程.利用常规天气资料和数值预报产品,对此次过程的天气学预报与数值模式预报进行对比分析.分析发现,此次过程伴随中亚地区的高压脊轴向顺时针旋转促使脊前横槽快速转竖南压,引导强冷空气向南爆发,导致宁夏气温骤降形成寒潮;数值预报产品对冷高压中心强度预报偏低,是造成预报员对冷高压强度估计偏弱的主要原因;模式预报冷高压最强时段较实况偏晚,加之预报员对寒潮爆发速度估计偏慢,是21日最低气温预报失误的主要原因;WRF模式的温度预报在此次过程中反映出良好的预报能力,为寒潮预报提供了可靠依据,可作为短期温度预报的基础.

On 21 December 2008,a cold wave weather process occurred in Ningxia.Based on the daily observation data and numerical forecast products,the synoptic and numerical forecasting of this cold wave were analyzed with comparative methods.The results show that,with the clockwise rotation of ridge axial in central Asian,the cross-trough front of ridge turned vertically to southward quickly,which guided the strong cold air broke out southward,and finally resulted in the cold wave in Ningxia.The key reason for surface high-pressure center underestimated by forecaster is that the numerical forecasting value was lower than that of fact;the main cause of the forecasting failure to the minimum temperature on 21 December was that the numerical forecast of the strongest period of cold high-pressure was later than the actual conditions,and the outbreak of the cold wave was faster than forecaster＇s estimate.For its good performance on the temperature forecasting in this case,WRF was capable of being used as the basis of short-term temperature forecasting.