Can the aerosol pollution extreme events be revealed by global reanalysis products?

• Published in: The Science of the total environment Vol. 923; p. 171424
• Main Authors: Li, Jingtao, Wang, Tianhe, Li, Chenrui, Yan, Hongru, Alam, Khan, Cui, Yang, Amonov, Mansur O., Huang, Jianping
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-05-2024
• Subjects: AERONET/SKYNET; Aerosol pollution extreme events; CAMS; Evaluation; MERRA-2; Evaluation; MERRA-2; Aerosol pollution extreme events; CAMS; AERONET/SKYNET
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.171424

Extreme aerosol pollution poses significant risks to the climate, environment, and human health. To investigate the formation and impacts of aerosol pollution extreme events (APEE), the reanalysis product presents meticulous spatiotemporal information on the three-dimensional distribution of aerosols. However, there is a lack of comprehensive evaluation and information regarding the data quality of reanalysis products employed in APEE research, as well as limited understanding of their spatial and temporal distribution, variation, and long-term trends. To address this scientific gap, we conducted a global study for distribution and variation patterns of APEE using two widely-used reanalysis products, MERRA-2 (Modern-Era Retrospective Analysis for Research-2) and CAMS (Copernicus Atmospheric Monitoring Service). The APEE was defined here as a day when the daily aerosol optical depth (AOD) exceeding its 90th percentile for a given station and month. Eleven distinct land regions worldwide were selected for evaluation by comparing both reanalysis products with MODIS satellite products and ground-based observations in terms of frequency, intensity, and temporal trends of APEE. The analysis indicates that MERRA-2 and CAMS exhibit high matching rates (70 % and 80 %, respectively) in terms of occurrence timeline for APEE at monthly and seasonal scales, while also exhibiting strong monthly correlation coefficients (>0.65) with ground-based observations over selected regions. The total AOD (−0.002 ∼ −0.123 decade−1), APEE AOD (−0.004 ∼ −0.293 decade−1), and APEE frequency (−0.264 ∼ −1.769 day month−1 decade−1) of both observations and reanalysis products in most regions showed a decreasing trend with various magnitude, except for some regions such as South Asia where the trend is increasing. Based on the aforementioned evaluation, it is evident that reanalysis products are effective and useful in identifying the temporal trends associated with APEE.
[Display omitted]
•CAMS and MERRA-2 well predicted aerosol pollution extreme events (APEEs) globally.•The monthly matching rate of APEEs days between reanalysis and ground observations is higher than 70 %.•Reanalysis products and ground-based observations exhibit strong correlation in the monthly intensity of APEEs matching.•APEEs are decreasing in most regions except South Asia, the Middle East, and western North America.