In this work, the spatial extent of new particle formation (NPF) events and the relative probability of observing particles originating from different spatial origins around three rural sites in eastern China were investigated with the NanoMap method, using particle number size distribution (PNSD) data and air mass back trajectories. The length of the datasets used were 7-year, 1.5-year and 3-year at rural sites Shangdianzi (SDZ) in North China Plain (NCP), Mt. Tai (TS) in central eastern China, and Lin'an (LAN) in Yangtze River Delta region in eastern China, respectively. Regional NPF events were observed to occur with the horizontal extent larger than 500&thinsp;km at SDZ and TS, favored by the fast transport of northwesterly air masses. At LAN, however, the spatial footprint of NPF events was mostly observed around the site within 100&ndash;200&thinsp;km. Difference in the horizontal spatial distribution of new particle source areas at different sites was connected to typical meteorological conditions at the sites. Consecutive large-scale regional NPF events were observed at SDZ and TS simultaneously and were associated with a high surface pressure system dominating over this area. Simultaneous NPF events at SDZ and LAN were seldom observed. At SDZ the polluted air masses arriving over NCP were associated with higher particle growth rates (<i>GR</i>) and new particle formation rates (<i>J</i>) than air masses from Inner Mongolia (IM). At TS the same phenomenon was observed for <i>J</i>, but <i>GR</i> was somewhat lower in air masses arriving over NCP compared to those arriving from IM. The capability of NanoMap to capture the NPF occurrence probability depends on the length of the dataset of PNSD measurement, but also on topography around the measurement site and typical air mass advection speed during NPF events. Thus the long-term measurements of PNSD in planetary boundary layer are necessary in the further study on spatial extent and probability of NPF events. The spatial extent, relative probability of occurrence and typical evolution of PNSD during NPF event presented in this study provide valuable information to further understand the climate and air quality effect of new particle formation.
Shen, X., Sun, J., Kivekäs, N., Kristensson, A., Zhang, X., Zhang, Y., … Zhou, H. (2018). Spatial distribution and occurrence probability of regional new particle formation events in eastern China. Atmospheric Chemistry and Physics, 18(2), 587–599. https://doi.org/10.5194/acp-18-587-2018