High-resolution mapping of ground-level PM2.5 in China using FY-4A and FY-4B TOA reflectance with seamless coverage

Zhang, T., Hua, C., Zhang, L., & Zhang, C. (2026). High-Resolution Mapping of Ground-Level PM2.5 in China Using FY-4A and FY-4B TOA Reflectance with Seamless Coverage. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 1-15. https://doi.org/10.1109/JSTARS.2026.3655086

Abstract

Fine particulate matter (PM2.5) is a key air pollutant that significantly impacts ambient air quality and public health. High-resolution, full-coverage PM2.5 datasets are essential for effective air quality monitoring and management. In this study, we develop an innovative framework to estimate ground-level PM2.5 concentrations across China with high spatiotemporal resolution by synergistically integrating top-of-atmosphere (TOA) reflectance data from FengYun-4A (FY-4A) and FengYun-4B (FY-4B) geostationary satellites. By exploiting the complementary orbital coverage and observation geometry of both satellites, we established a robust random forest model to derive hourly daytime PM2.5 concentrations at 1 km resolution throughout 2023. This dual-satellite fusion strategy significantly enhances data availability by up to 63% while achieving higher estimation accuracy compared to single-satellite approaches. To address the remaining data gaps, we proposed an advanced spatiotemporal interpolation method (ST-IDW) with adaptive weighting schemes, generating a daily seamless dataset-dubbed FY-4 and 4B Geostationary PM2.5 (FYGPM). Comprehensive validation demonstrates that the FYGPM dataset holds unparalleled advantages in data coverage while achieving accuracy comparable to the leading existing product. It successfully captures fine-scale pollution patterns, intra-urban variability, and urban-rural gradients across China, with spatial distributions showing strong alignment with impervious surface patterns and successfully identifying low PM2.5 concentrations over water bodies. This study represents the first operational high-resolution PM2.5 product for China derived from dual geostationary satellite observations. The FYGPM dataset serves as a valuable resource for air quality research, urban pollution analysis, and environmental policy-making at both national and local scales.

Publisher

Institute of Electrical and Electronics Engineers

Rights

CC BY

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