昭通市50年未遇低温冰冻灾害环流特征分析

应用NECP2．5°×2．5°的分析资料，对形成2008年1月12日到2月20日昭通市50年未遇的特重低温冰冻灾害性天气的环流背景及影响系统分阶段进行了分析，表明：在较为稳定的高纬环流形势下，受对流层中低层低槽东移和地面云贵静止锋的持续影响，是造成昭通市持续性低温冰冻天气的原因，由南支槽与静止锋结合产生的强降雪天气过程形成的罕见雪灾，加重了持续性低温冰冻天气的影响。由于主要影响系统冷高压、高空槽、静止锋的强弱进退和系统配置的差别而造成天气表现在过程中的各个阶段有所不同。另外，逆温层长时间维持和地面温度持续低于0℃是雨凇持续时间创历史记录的主要原因。

ANALYSIS OF CIRCULATIONS FEATURES DURING THE SEVERE COLD, ICE-SNOW AND FROZEN DISASTERS IN ZHAOTONG IN 2008

Using NECP Global Data Assimilation System data, atmosphere circulations features and causes of the unprecedented the Severe cold, ice - snow and frozen disasters in Zhaotong from Jan. 12 to Feb. 20, 2008 was analyzed, according to different stages. The results show that on condition that the steady circulation located over high latitude, the disasters was caused by persistent influences of the lower level trough and the Yunan - Guizhou stationary front. The southern branch westerly trough combine with stationary front lead to heavy snowstorm which greatly strengthened the disasters. Differ in combination of the cold high pressure, southern branch westerly trough and stationary front results in the different weather. In addition, the persistence of the inversion layer and the ground temperature belowed 0℃ was the main causes of the recorded frozen rain in this disaster.