乌鲁木齐地区一次降雪天气特征及其形成机制研究

Study on the Characteristics and Formation Mechanism of a Snowfall Event in Urumqi Area

摘要: 利用地面观测、AQI (空气污染数据)、卫星云图等资料，综合分析了2018年12月1~2日发生于天山北坡中段的乌鲁木齐地区的一次降雪伴沙尘天气的天气特征及形成机制。结果表明，西伯利亚大槽携带强冷空气南下配合副热带锋区在新疆地区汇合，造成沿天山一带的强降雪，强锋区伴随的密集的温度梯度形成较大的气压差，造成克拉玛依地区大风，而克拉玛依附近大风产生的沙尘粒子在高空风的输送下经过准噶尔盆地的古尔班通古特沙漠向东南方向移动，造成沙漠南缘的莫索湾、蔡家湖、阜康和乌鲁木齐等地长时间沙尘天气。乌鲁木齐市的沙尘雪天气是先出现降雪后出现沙尘伴降雪，沙尘伴随降雪而下落，因此地面积雪呈现出“下白上黄”特征。

Abstract: Using data from surface observations, satellite cloud images, and other sources, this study comprehensively analyzed the weather characteristics and formation mechanism of a snowfall accompanied by sand and dust event that occurred in the Urumqi area, located in the middle section of the northern slope of the Tianshan Mountains, from December 1 to 2, 2018. The results show that the strong cold air carried by the Siberian trough moved southward and converged with the subtropical frontal zone in the Xinjiang region, causing heavy snowfall along the Tianshan Mountains. The dense temperature gradient associated with the strong frontal zone created a large pressure difference, leading to strong winds in the Karamay area. The sand and dust particles generated by the strong winds near Karamay were transported southeastward by upper-level winds through the Gurbantünggüt Desert in the Junggar Basin, resulting in a long-lasting sand and dust weather in areas such as Mosuowan, Caijiahu, Fukang, and Urumqi on the southern edge of the desert. The “snow with sand and dust” weather in Urumqi was characterized by snowfall first, followed by snowfall accompanied by sand and dust. As the sand and dust fell together with the snow, the accumulated snow on the ground showed the characteristic of “white at the bottom and yellow on the top”.