【摘要】 以≤-2.0℃地面最低温度作为霜冻指标,利用河西走廊中西部10个气象观测站点的实时观测资料和相应的数值预报资料,采用现代天气诊断方法,对2004年5月3～4日特强霜冻天气过程进行了探讨分析。针对霜冻天气发生发展的特点,在剖析环流背景的基础上,重点分析了500 hPa的v风场及其廓线;总能量的平流变化等物理量。结果表明,北风带的东移南扩是造成此次大范围霜冻天气的关键因子,总能量的持续偏低使得强霜冻的持续时间延长。更多还原

【Abstract】 Taking ≤-2.0 ℃ lowest surface temperature as the index of frost,the causes of "2004.5.3-4"strong frost in west and middle of Hexi Corridor were discussed by using ten weather observational stations data in the areas and the numerical weather prediction data.Based on synoptic diagnose method,the background of atmospheric circulation during strong frost were analyzed.500 hPa field of v-wind and its profile characteristics and the total energy variation of horizontal advection were analyzed.The results showed that the strong north wind moved from northwest to southeast was the key factor,and that the total energy continuous low led to the strong frost extend for a long time.更多还原