【摘要】 利用2020年3月份ERA5再分析资料、地面自动站观测资料及MICAPS资料，分析了3月11-12日青海大部地区出现大风沙尘天气的形成机制以及影响因素。结果表明：（1）此次大风沙尘天气发生在200 hPa急流维持、500～700 hPa冷平流明显的环流背景下，而地面冷锋过境是此次过程的触发机制；（2）从垂直速度、散度、涡度等物理量分析来看，西宁附近东西方向上构成了东部高空辐合、地面辐散，西部高空辐合的锋面次级环流，增强了锋后下沉运动的发展；（3）此次过程中大气层结在白天趋于不稳定，地面至500 hPa接近干绝热，导致湍流活动强，动量下传强，地面风速大，是青海省比较典型的高空急流动量下传和大气层结不稳定共同作用所引起的大风天气过程。分析结果可为未来类似大风沙尘天气过程预报提供参考依据。更多还原

【Abstract】 Based on the ERA5 reanalysis data from European centre for medium-range weather forecasts, ground automatic station observation data and MICAPS data from March 11 to 12,2020, this paper analyzes the formation mechanism and influencing factors of a dust pollution event in the northeast of Qinghai Province. The results show that:(1)The strong windy and dusty weather occurred under the background of 200 h Pa jet stream and obvious cold advices from 500 hPa to 700 hPa circulation. The transit of ground cold front is the trigger mechanism of this process.(2) From the analysis of vertical velocity, divergence, vorticity and other physical quantities, it can be seen that the east-west direction near Xining formed a frontal secondary circulation with upper altitude convergence in the east, surface divergence and upper altitude convergence in the west. This enhances the development of the subsidence motion behind the front.(3) In this process, the atmospheric junction tends to be unstable during the day, and the ground is still close to dry adiabatic when it reaches 500 hPa, resulting in strong turbulent activity, strong momentum down transmission, and high surface wind speed. This is a typical gale weather process in Qinghai Province, which is caused by the combined effect of the momentum transmission of the upper jet stream and the instability of the atmosphere. The analysis results can provide reference for the forecast of similar wind and dust weather processes in the future.更多还原