Exploring the mechanisms of dust emission and transport based on observations and GEOS-Chem simulations

Abstract. Dust aerosols play a significant role in climate and air quality, yet understanding of their emission and long-range transport mechanisms remains incomplete. By looking into a severe dust event occurred in northern China on April 2025, and conducting the comparative analysis against a 30-year climatic average and the historical dust events using multi-source observations and the GEOS-Chem model simulations, we systematically investigate its meteorological conditions, emission mechanisms, and transport processes. Results show that the dust event in April was originated in the western Inner Mongolia (WIM) source region, accompanied by wind speeds exceeding 8 m s−1 and hourly PM10 concentrations above 1900 µg m−3, and affected the southern China including Yangtze River Basin and Hainan Province. Under the influence of the Siberian high-pressure system and the Mongolian cyclone, the WIM experienced persistent dry-cold advection (relative humidity around 20 %, wind speeds exceeding 10 m s−1). Three months preceding the dust event, the WIM exhibited significantly high temperatures (∼+2 °C), reduced precipitation (∼-25 mm) and low volumetric soil water (∼-0.02 m3 m−3). Comparison with two other severe historical dust events in year 2021 and 2023, demonstrating that long-range transport in 2025 was primarily due to strong northerly winds that effectively guided southward transport of dust aerosols, which was mainly due to the sustained interaction between an intense Siberian High and a Mongolian cyclone, coupled with the southerly position of the cyclone. Furthermore, the dust in 2025 consistently moved southward but generally behind the rainband, which imply relatively low wet scavenging and thereby enabling stable long-range transport. The study confirms that persistent drought and strong winds triggered intense dust emission, and airflow transport under specific synoptic conditions dominated the long-range dust transport.