摘要
该文利用常规观测资料、NCEP 1°×1°分析资料对2014年2月发生在怀化的3次低温雨雪天气过程的成因和降水相态变化特征进行了多种资料诊断分析,得到以下结论:3次过程是在有利的大尺度环流背景下发生的,贝加尔湖冷涡稳定维持,冷涡底部多短波槽活动,地面冷高压主体稳定少动,地面冷空气从东路分股南下;低层西南急流将来自印度洋的暖湿空气源源不断地输送到长江流域,冷暖气流在长江流域交汇,导致了持续雨雪天气的发生。3次过程中均有冷锋锋区自地面向高空倾斜,强锋区使低层和地面维持低温天气,暖湿空气则沿锋面强迫抬升,低层不稳定能量得以释放,有利于雨雪的发生。低层偏南气流的发展加强不但为降雪提供了水汽条件,也有利于冷暖气流的交汇和暖湿空气的垂直输送。降水相态的变化与温度层结特征以及气层厚度密切相关,冷式逆温层和700 h Pa与850 h Pa高度差小于155 dagpm的气层更有利于纯雪的出现。
Base on conventional observation data and NCEP 1°×1° reanalysis data, three rain and snow processes occurred in Huaihua in February, 2014 were analyzed. The results indicate that： Three processes happened in a large -scale circulation background, Lake Baikal cold vortex maintained stable, short wave troughs were quite active at the bottom of cold vortex, however, surface cold highs were less active, surface cold air moved southward along the east route; southeast airflows in the low layer transported the warm moist air from the Indian ocean to the Yangtze river basin continuously, cold and warm air converged over the Yangtze river basin which resulted in susrained rain and snow. In all three processes, cold fronts inclined from surface to high altitude, temperature remained low in the low layer and surface due to strong frontal zone, warm moist air was forced ascending along the frontal surface, instable energy was released in the low layer, thus leading to the rain and snow. The enhancement of southerly not only provided vapor conditions, but also was in favor of confluence of cold and warm airflows and vertical transportation of warm moist air. The change of precipitation phase state was closely related to the charac- teristics of temperature stratification and the thickness of air layer, cold inversion layer and the layer whose altitude difference between 700 hPa and 850 hPa was less than 155 dagpm both benefit the occurrence of snow.
出处
《贵州气象》
2016年第2期57-64,共8页
Journal of Guizhou Meteorology
关键词
低温雨雪
高空低槽
温度层结
对比分析
cold
rain and snow
low trough on upper level
temperature stratification
contrastive analysis
