昌都一次致灾大暴雪的过程分析

Analysis on the Process of a Heavy Snowstorm Causing Disasters in Changdu

利用常规气象资料、实况场以及卫星遥感数据对2017年11月23日昌都降雪天气过程的演变、动力条件等进行分析和总结。结果表明:东西伯利亚冷涡向南伸的大槽后部的偏北风使得冷空气从新疆西北路径、从西伯利亚北路径向高原输送,偏北风加强与孟加拉湾暖湿气流交汇是造成暴雪的主要环流背景;500hPa西南暖湿急流、200hPa高空急流、高原槽、地面中尺度辐合线是造成暴雪的触发机制。西南暖湿急流输送的大量水汽与高空急流的有利配合有助于上升运动的加强并释放潜热进一步维持上升运动,为暴雪强度的增强提供了有利条件。

Using conventional meteorological data,live field and satellite remote sensing data,the evolution and dynamic conditions of the weather system during the snowfall in Changdu on November 23,2017 were analyzed and summarized.The results show that the northerly wind at the back of the trough extending southward from the East Siberian cold eddy made the cold air transport from northwest Xinjiang to the plateau from the North Siberian route.The main circulation background of the snowstorm was the convergence of northerly wind and warm-wet air flow in the Bay of Bengal.The favorable cooperation between the large amount of water vapor transported by the southwest warm-wet jet and the upper jet helped to strengthen the ascending motion and release latent heat to further maintain the ascending motion,which provided favorable conditions for the enhancement of the snowstorm intensity.