西北一次强沙尘天气的数值模拟及其诊断

ust storms are a major weather hazard in arid and semiarid regions, causing significant harm to human health and welfare and productivity. This study examined a severe dust storm event in northwest China using surface observation data from the National Meteorological Information Center, MODIS satellite data, and urban air quality data from March 18 to 23, 2023. The study combined the HYSPLIT backward trajectory model and the WRF-Chem atmospheric chemistry model to examine the dust source and impact range, focusing on the mechanisms behind the severe dust storm at Zhangye, a central site along the transport path. The main findings were that the dust storm affected much of northern China in phases, with dust emissions occurring in distinct regions on March 19, 20, and 21, each with unique transport ranges and impact areas. Dust in the Hexi Corridor primarily originated from Jiuquan. WRF-Chem simulations showed that the highest PM10 concentration occurred at Zhangye Station, reaching 6966.7 gm-3 The dust event in Zhangye originated from upstream dust transport and local dust emission. First, near- surface intensenorthwesterly winds over 16 ms-1 near Jiuquan, under unstable atmospheric conditions, triggered upward movement, which lifted dust particles to high altitudes and transported them downstream, where they settled around 3-4 km above Zhangye. Second, before the arrival of upstream dust, Zhangyes lower atmosphere exhibited instability, and the convergence of strong surface winds and wind direction triggered local dust uplift, further intensifying the dust storm.