Abstract:From 9 to 15 April 2023, a rare sand-dust weather event lasted for 6 days in the Beijing-Tianjin-Hebei Region. Utilizing conventional meteorological data, reanalysis data, and data obtained by new detection methods such as wind-profiling radar and lidar, this study analyzes the characteristics and maintenance mechanisms of the sand-dust weather in Beijing-Tianjin-Hebei Region. The results show that this sand-dust weather event was caused by the influence of a Mongolian cyclone, two cold fronts, and a persistent southwesterly flow. During the Mongolian cyclone phase, the sand originated from southern Mongolia was lifted and transported along the 700 hPa jet stream axis, forming near-surface blowing sand or floating dust through dry deposition. In the cold front phase, extensive dust sources and the passage of a surface cold front caused a rapid increase in surface wind speed, lifting large amounts of sand and dust, which then traveled to Beijing-Tianjin-Hebei Region along the low-level jet in the troposphere and was rapidly transported to the surface with the descending airflow behind the cold front. During the southerly airflow phase, influenced by the return of sand sources from the middle and lower reaches of the Yangtze River, sand-dust was continuously transported northward under the action of the southerly airflow behind the surface high pressure system, reaching relatively low altitudes and forming mainly blowing sand or floating dust through dry deposition on the surface. Characteristics of the sand and dust varied under the influence of different systems. During the Mongolian cyclone phase, the sand had a weaker impact but a higher upper boundary height; during the cold front phase, the sand-dust concentrations were high and the visibility was low. Then, a sandstorm occurred after the cold front’s passage and lasted for two hours, followed by clean air thirteen hours later; during the southerly airflow phase, the sand-dust lasted longer but was the weakest in intensity. During this sand-dust weather, the local turbulent dissipation rate increased three hours before the sand-dust concentration increased, which has good indicative significance for dust monitoring and forecasting. The above analysis results have a good reference value for future dust weather forecasting.