Spatially continuous mapping of hourly ground ozone levels assisted by Himawari-8 short wave radiation products

Abstract

Ground-level ozone concentration has demonstrated a noteworthy increasing trend in easternChina over the past 20 years, exerting inescapable influence on atmospheric chemistry, climate change, and air pollution. To support epidemiological research and prevent further environmental pollution, it is imperative to monitor the spatio-temporal distribution of ground-level ozone pollution. Geostationary satellites prove a promising approach to make up for the limitation of ground-based measurement and polar-orbiting observation by acquiring regional atmospheric measurements of high spatio-temporal resolution, yet inevitably exists spatial discontinuity caused by the cloud cover. This study established an effective model to produce spatially continuous estimation of hourly 5 km ground-level ozone (O3) concentrations covered most of China by firstly integrating hourly Himawari-8 SWR product from 1 March 2018 to 28 February 2019. The R2 values of established model of all available samples for direct fitting, 20-fold cluster-based CV, 10-fold site-based CV, and 10-fold sample-based CV reaches 0.95, 0.69, 0.87 and 0.89, respectively, implying superior universality and spatial scalability. The R2 values of seasonal site-based CV range from 0.78 (Winter) to 0.86 (Autumn), and that of hourly site-based CV ranges from 0.73 (0900 BST) to 0.86 (1300 BST). In addition, this study displayed the spatial distribution of the estimated ground-level ozone from the temporal scales of quarter, week, and day. Summer (87.1 ± 28.2 μg/m3) proves to be the most polluted season, and the least polluted season is winter (59.4 ± 16.1 μg/m3). 1400 BST appears to be the most polluted hour (87.4 ± 26.6 μg/m3) and 0900 BST is the least polluted hour (59.1 ± 16.8 μg/m3). Remarkable “weekend effect of ozone” has been detected in northeast Hebei and Sichuan Basin and Yangtze River valley.