Tracking Air Pollution in China: Near Real-Time PM₂.₅ Retrievals from Multisource Data Fusion
2021
Geng, Guannan | Xiao, Qingyang | Liu, Shigan | Liu, Xiaodong | Cheng, Jing | Zheng, Yixuan | Xue, Tao | Tong, Dan | Zheng, Bo | Peng, Yiran | Huang, Xiaomeng | He, Kebin | Zhang, Qiang
Air pollution has altered the Earth’s radiation balance, disturbed the ecosystem, and increased human morbidity and mortality. Accordingly, a full-coverage high-resolution air pollutant data set with timely updates and historical long-term records is essential to support both research and environmental management. Here, for the first time, we develop a near real-time air pollutant database known as Tracking Air Pollution in China (TAP, http://tapdata.org.cn/) that combines information from multiple data sources, including ground observations, satellite aerosol optical depth (AOD), operational chemical transport model simulations, and other ancillary data such as meteorological fields, land use data, population, and elevation. Daily full-coverage PM₂.₅ data at a spatial resolution of 10 km is our first near real-time product. The TAP PM₂.₅ is estimated based on a two-stage machine learning model coupled with the synthetic minority oversampling technique and a tree-based gap-filling method. Our model has an averaged out-of-bag cross-validation R² of 0.83 for different years, which is comparable to those of other studies, but improves its performance at high pollution levels and fills the gaps in missing AOD on daily scale. The full coverage and near real-time updates of the daily PM₂.₅ data allow us to track the day-to-day variations in PM₂.₅ concentrations over China in a timely manner. The long-term records of PM₂.₅ data since 2000 will also support policy assessments and health impact studies. The TAP PM₂.₅ data are publicly available through our website for sharing with the research and policy communities.
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