京津冀地区一次持续时间较长浮尘天气的分析

2017年5月3—4日京津冀地区出现了一次持续较长时间的浮尘天气,给京津冀地区的生产和生活带来了较大的影响。从气象条件方面分析了浮尘天气的成因及维持机制,并使用气象、环境观测、激光雷达探测、后向轨迹模式产品等分析了此次浮尘天气的观测事实。结果表明,此次过程是在蒙古气旋强烈发展东移的过程中,经过蒙古国中部、甘肃、内蒙中西部的沙源地后形成扬沙、沙尘暴,大量的沙尘粒子随高空偏西西北气流漂至京津冀上空后沉降而形成的,本地沙源没有补充。激光雷达可以清晰地监测到沙尘的传输高度基本在2～4 km。浮尘天气期间,沙尘高度在2 km以下。浮尘维持30 h以上的原因:(1)高空受东、西两槽间的纬向环流控制,地面处于鞍型场,风速小,不利于沙尘粒子的扩散;(2)边界层内湍流活动旺盛,且中低层基本是中性层结状态,沙尘粒子不易沉降。

Observation and analysis of a dust process occurring over the beijing-tianjin-hebei region

A severe dust storm occurred in the beijing-tianjin-hebei region from May 3 to 4, 2017, which brought great impact on production and life in the beijing-tianjin-hebei region. This paper mainly analyzed the cause of formation of dust weather from meteorological conditions, and revealed the source and transmission height of dust by using meteorology, environmental observation, lidar detection, and backward trajectory model products, and revealed the fact of dust processer in the beijing-tianjin-hebei region. The results show that this process is due to the eastward development of the high trough, the strong development of the Mongolian cyclone on the ground through northwest China, central and western Inner Mongolia and other places formed the sandstorm, and a large number of small dust particles with the northwest westerly airflow to the beijing-tianjin-hebei over the subsidence formed dust . According to the analysis of the lidar detection data and the tracking of the particles, the transmission characteristics of the dust are as follows: the sand comes from central Mongolia and central and western Inner Mongolia, and it is transported to the beijing-tianjin-hebei region with the northwest wind flow. After reaching the beijing-tianjin-hebei region, the dust mainly concentrates below 2km. The pattern is in the saddle field on the ground and the wind speed is small, which is not conducive to the diffusion of sand particles. In addition, the middle and lower layers are basically in a neutral stratification state, with turbulent activity flourishing, and dust particles are not easy to settle, resulting in the dust process maintaining above 30h.