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Aircraft observations of aerosol and BC during the East Asian dust storm event: Vertical profiles, size distribution and mixing state
Abstract The vertical structure of meteorological elements, black carbon (BC), and aerosols were in situ characterized by the King Air 350 aircraft measurements over the northeast of China during an East Asian dust storm event from April 10 to 13, 2023. The main causes of this dust storm event were the strong winds generated by the Mongolian cyclone, the cold front on the ground provided dynamic conditions, and the unstable atmospheric state provided thermal conditions and less precipitation in the dust source areas led to exposed the ground surface. The number concentrations of BC and aerosol had significant vertical distribution. The number concentration of aerosol in the dust storm (DS) layer increased rapidly with height, while the number and mass concentrations of BC were higher and varied slightly with height. The BC core mass median diameters (MMD) first increased with height, reaching a maximum value of 0.24 μm at 3000 m; and it rapidly decreased to 0.18 μm at 3200 m and then varied slightly with height above 3200 m. BC's bulk relative coating thickness (coated diameter divided by uncoated core diameter Dp/Dc) first decreased with height, reaching a minimum value of 1.16 at 3000 m, then increased with height, reaching a maximum of 1.38 (4250 m). A wind shear layer (7.9 m s−1 at 1850 m) with a sudden drop in temperature (the cooling rate can reach 7.4 °C·(100 m)−1) at 1900 m hinders the transportation of dust particles to the ground, allowing the dust particles to be transported at long-term distances. There were two stratifications in the dust storm layer: DS1 (1700–3000 m, the vertical wind speed was downward, the horizontal wind speed was small) and DS2 (3000–4500 m, the vertical wind speed was upward, the horizontal wind speed was large). The distinct atmospheric flow field conditions between DS1 and DS2 led to different BC and aerosol pollution characteristics. In DS2, the number concentrations of BC and aerosol were higher, the aging ratio of BC particles was higher, and the size of the core particle of BC was smaller. The concentrations of BC, aerosol, Dp/Dc, and MMD in DS2 were 1.1, 59.0, 1.02, and 0.84 times higher than those in DS1, respectively. Dust particles transported over long distances were primarily small. The number concentrations of aerosols at 0.1–0.12 μm and 0.1–0.24 μm were higher in DS1 and DS2, respectively. Still, the number concentration of aerosol at 0.12–0.28 μm in DS1 was lower than in the planetary boundary layer (PBL) and residual layer (RL).
Graphical abstract Display Omitted
Highlights Aircraft in situ observations of aerosol and BC during the East Asian dust storm. Two dust layers: Dust Storm (DS)1/DS2 (vertical wind speed (WS) downward/upward, horizontal WS small/large). Wind shear layer with T sudden drop at 1900m hinders dust transport to ground. Dust particles were mainly small particles (0.1–0.24 μm) during the long-term distance transport.
Aircraft observations of aerosol and BC during the East Asian dust storm event: Vertical profiles, size distribution and mixing state
Abstract The vertical structure of meteorological elements, black carbon (BC), and aerosols were in situ characterized by the King Air 350 aircraft measurements over the northeast of China during an East Asian dust storm event from April 10 to 13, 2023. The main causes of this dust storm event were the strong winds generated by the Mongolian cyclone, the cold front on the ground provided dynamic conditions, and the unstable atmospheric state provided thermal conditions and less precipitation in the dust source areas led to exposed the ground surface. The number concentrations of BC and aerosol had significant vertical distribution. The number concentration of aerosol in the dust storm (DS) layer increased rapidly with height, while the number and mass concentrations of BC were higher and varied slightly with height. The BC core mass median diameters (MMD) first increased with height, reaching a maximum value of 0.24 μm at 3000 m; and it rapidly decreased to 0.18 μm at 3200 m and then varied slightly with height above 3200 m. BC's bulk relative coating thickness (coated diameter divided by uncoated core diameter Dp/Dc) first decreased with height, reaching a minimum value of 1.16 at 3000 m, then increased with height, reaching a maximum of 1.38 (4250 m). A wind shear layer (7.9 m s−1 at 1850 m) with a sudden drop in temperature (the cooling rate can reach 7.4 °C·(100 m)−1) at 1900 m hinders the transportation of dust particles to the ground, allowing the dust particles to be transported at long-term distances. There were two stratifications in the dust storm layer: DS1 (1700–3000 m, the vertical wind speed was downward, the horizontal wind speed was small) and DS2 (3000–4500 m, the vertical wind speed was upward, the horizontal wind speed was large). The distinct atmospheric flow field conditions between DS1 and DS2 led to different BC and aerosol pollution characteristics. In DS2, the number concentrations of BC and aerosol were higher, the aging ratio of BC particles was higher, and the size of the core particle of BC was smaller. The concentrations of BC, aerosol, Dp/Dc, and MMD in DS2 were 1.1, 59.0, 1.02, and 0.84 times higher than those in DS1, respectively. Dust particles transported over long distances were primarily small. The number concentrations of aerosols at 0.1–0.12 μm and 0.1–0.24 μm were higher in DS1 and DS2, respectively. Still, the number concentration of aerosol at 0.12–0.28 μm in DS1 was lower than in the planetary boundary layer (PBL) and residual layer (RL).
Graphical abstract Display Omitted
Highlights Aircraft in situ observations of aerosol and BC during the East Asian dust storm. Two dust layers: Dust Storm (DS)1/DS2 (vertical wind speed (WS) downward/upward, horizontal WS small/large). Wind shear layer with T sudden drop at 1900m hinders dust transport to ground. Dust particles were mainly small particles (0.1–0.24 μm) during the long-term distance transport.
Aircraft observations of aerosol and BC during the East Asian dust storm event: Vertical profiles, size distribution and mixing state
Liu, Xingguang (author) / Zhao, Delong (author) / Niu, Zhongqing (author) / Zhao, Guangna (author) / Ding, Deping (author) / Chen, Yi (author) / Liu, Haotian (author)
Atmospheric Environment ; 327
2024-04-01
Article (Journal)
Electronic Resource
English