High-altitude and long-range transport of aerosols causing regional severe haze during extreme dust storms explains why afforestation does not prevent storms

Ping Guo (1) , Shaocai Yu (2, 3) , Liqiang Wang (3) , Pengfei Li (3) , Zhen Li (3) , Khalid Mehmood (3) , Xue Chen (3) , Weiping Liu (3) , Yannian Zhu (4) , Xing Yu (4) , Kiran Alapaty (5) , Eric Lichtfouse (6) , Daniel Rosenfeld (7) , John Seinfeld (2)

1 College of Water Resources and Civil Engineering [Beijing]
2 CALTECH - California Institute of Technology
3 Zhejiang University
4 Meteorological Institute of Shaanxi Province
5 U.S. Environmental Protection Agency
6 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
7 HUJ - The Hebrew University of Jerusalem

Climate change is predicted to induce more extreme events such as storms, heat waves, drought and floods. Dust storms are frequently occurring in northern China. Those storms degrade air quality by decreasing visibility and inducing cardiovascular and respiratory diseases. To control dust storms, the Chinese government has launched a large-scale afforestation program by planting trees in arid areas, but the effectiveness of this program is still uncertain because the trajectories and altitudes of dust transport are poorly known. In particular, afforestation would be effective only if dust transport occurs at low altitudes. To test this hypothesis, we analyzed the extreme dust storm from May 2 to 7, 2017, which resulted in record-breaking dust loads over northern China. For that, we used dust RGB-composite data from the Himawari-8 satellite and the cloud-aerosol lidar, moderate-resolution imaging spectroradiometer data, and surface monitoring data. The source regions of the dust storms were identified using the hybrid single-particle Lagrangian integrated trajectory model and infrared pathfinder satellite observation. Contrary to our hypothesis, results show that dust is transported at high altitude of 1.0-6.5 km over long distances from northwestern China. This finding explains why the afforestation has not been effective to prevent this storm. Results also disclose the highest particulate matter (PM) concentrations of 447.3 μg/m 3 for PM 2.5 and 1842.0 μg/m 3 for PM 10 during the dust storm. Those levels highly exceed Chinese ambient air quality standards of 75 μg/m 3 for PM 2.5 and 150 μg/m 3 for PM 10 .

Mots clés: optical properties; satellite observation; massive dust storm; regional severe haze

Domaines: Géochimie; Milieux et Changements globaux; Ingénierie de l'environnement; Autre

Ping Guo, Shaocai Yu, Liqiang Wang, Pengfei Li, Zhen Li, et al.. High-altitude and long-range transport of aerosols causing regional severe haze during extreme dust storms explains why afforestation does not prevent storms. Environmental Chemistry Letters, 2019, 17 (3), pp.1333-1340. ⟨10.1007/s10311-019-00858-0⟩. ⟨hal-02267190⟩