Spatial distribution of PM2.5 chemical components during winter at five sites in Northeast Asia: High temporal resolution measurement study

Predicting Atmospheric Particle Phase State Using an Explainable Machine Learning Approach Based on Particle Rebound Measurements

“…However, this dramatic decline did not appear in the case of NO x (NO x = NO + NO 2 ) concentrations. Consequently, nitrate gradually became the dominating component in fine particles. ,,, The effects of nitrate and sulfate on the particle phase state were evaluated in this study based on a hypothetical aerosol composition using the constructed ML model. Assuming Finorg = 0.3, 0.5, and 0.7, the predicted f versus nitrate/sulfate mass fraction ratio (F NO 3 /F SO 4 ) under various RHs is shown in Figure (a–c).…”

“…In conclusion, at a given Finorg , the increase of the nitrate allowed the particles to be in the liquid state at lower RH. It should be noticed that the Finorg ranged from 0.22 to 0.73 in continental particles; therefore, the selected Finorg could represent the aerosol chemical composition in the ambient atmosphere. In addition, in the measurement data set (see Section ), the F NO 3 /F SO 4 varied from 0.06 to 4.67.…”

“…In European countries, the aerosol chemical composition is available via the Global Atmosphere Watch Programme (GAW, ); for cities in the United States, aerosol chemical composition data are obtained via Interagency Monitoring of Protected Visual Environments (IMPROVE, ). In Asian and African cities, data are collected from previous field campaigns. − The seasonal average RHs are calculated based on the global meteorological data set via the National Climatic Data Center (NCDC, ).…”

Influence of Relative Humidity and Composition on PM2.5 Phases in Northeast Asia

“…As a part of the Fine Particle Research Initiative in East Asia considering National Differences (FRIEND) project, which was launched in 2020 to investigate the mechanisms and characteristics of aerosol pollution in Northeast Asia, ,− we investigated the physicochemical properties of PM 2.5 in four different sites in Northeast Asia: Beijing (40.25° N, 116.19° E), Seoul (37.61° N, 126.93° E), Seosan (36.77° N, 126.49° E), and Ulaanbaatar (47.91° N, 106.94° E) (Figure S1). The measurement sites in Beijing, Seoul, and Ulaanbaatar are in urban environments, − whereas the site in Seosan is in a rural area. , Concurrent field measurements were conducted in these four cities with daily collection of PM 2.5 samples covering three seasons (winter, summer, and spring) between 2020 and 2022 (Tables S1 and S2, Figure S2). In total, 92 PM 2.5 filter samples were analyzed to determine their phase states.…”

“…The measurement sites in Beijing, Seoul, and Ulaanbaatar are in urban environments, 46−48 whereas the site in Seosan is in a rural area. 42,49 Concurrent field measurements were conducted in these four cities with daily collection of PM 2.5 samples covering three seasons (winter, summer, and spring) between 2020 and 2022 (Tables S1 and S2, Figure S2). In total, 92 PM 2.5 filter samples were analyzed to determine their phase states.…”