Mega Asian dust event over China on 27–31 March 2021 observed with space-borne instruments and ground-based polarization lidar

Under the background of global climate change, the frequency of extreme weather events is ever-increasing. Climatic anomaly in dust source areas and intensive Mongolian cyclones jointly cause the reoccurrence of super dust storms in spring 2021. A mega dust storm broke out in southeast Mongolia on 27 March and significantly impacted air quality in China until 31 March. However, neither intensity nor affected areas are well depicted by the forecasting model. Here we report the horizontal distribution, transport path, dissipation, and influence on surface air quality of this event with the combination of space-borne and ground-based observations. Prudent analysis indicates a longer duration (5 days) and farther-south affected areas (25°N) than the previous report. Dust plumes were first transported to North and Northeast China, the Bohai Sea, and the Yellow Sea (28 March), and then respectively moved eastward to Korea-Japan regions and southward over mainland China (29 March), with PM 10 values > 500 μg m −3 in 64 cities. Dust aerosols over the Yellow Sea retraced to the coastal areas of East China on 29 March, resulting in severe degradation of air quality over mainland China (25–40°N and 105–120°E) during 29–31 March. On 31 March, dust particles in this region were gradually removed, attributed to the wet removal and the enhanced south branch of westerlies. In central China, ground-based polarization lidar observed dust ∼26 h earlier (1600 LT, 27 March) than surface PM 10 measurements. The dust plume showed a triple-layer vertical structure. The bottom layer mixed with local anthropogenic aerosols, concentrating most dust particles (>100 μg m −3 ); the upper two were composed of pure dust particles with lower mass concentration (<50 μg m −3 ). This study reveals the capacity of comprehensive observations with multiple approaches from both space and ground in real-time monitoring of mega dust storms and validating the sand storm forecasting. • A mega Asian dust storm is comprehensively observed with multiple instruments. • Event duration should be extended to 5 days compared with previous perception. • Farther south regions in China with latitude low to 25°N are also notably affected. • Optical properties and mass concentration profiles of dust in Wuhan are derived. • Combined observations from space and ground are beneficial to dust monitoring.