Spatial distribution and occurrence probability of regional new particle formation events in eastern China

Abstract

<p><strong>Abstract.</strong> 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 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 100–200 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.</p>

Measurement report: New particle formation characteristics at an urban and a mountain station in northern China

“…These values are comparable to earlier observations in urban Beijing and another regional background station in the North China Plain (NCP) (Wang et al, 2013). Earlier observations in the NCP and the Yangtze River Delta also show higher formation rates at urban sites than corresponding background sites by roughly a factor of 2 due to lower anthropogenic emissions at background sites (Wang et al, 2013;Dai et al, 2017;Shen et al, 2018). The much lower J 7 observed at the MT station is very likely associated with the low H 2 SO 4 concentration at this station, as we discussed above.…”

“…Actually, the wind conditions on other NPF event days at the MT station during our observation had similar characteristics that the wind directions were similar between 850 hPa and 10 m above ground level, indicating air masses were well mixed during NPF events. Earlier observations also found that NPF events happened uniformly within the mixing layer at their observation stations and that particle number size distribution remains roughly constant within the mixing layer (Shen et al, 2018;Lampilahti et al, 2021).…”

More Significant Impacts From New Particle Formation on Haze Formation During COVID‐19 Lockdown

“…Since no decrease are shown by both formation and growth rates during 2020‐LOCK, it can be concluded that the number concentration of >25 nm particle “seeds” produced by NPF events were at least not reduced, if not increased, during the lockdown. In addition, the occurrence of NPF events normally spread on large scale of over 100 km in the North China Plain (Shen et al., 2018), which can produce considerably high potential of >25 nm particle, regionally. In contrast, according to the discussion in 3.3, the PN Ait emitted by local fossil fuel combustion, which can serve as “seeds” in haze formation, showed clear downtrend due to the lockdown.…”

Observed coupling between air mass history, secondary growth of nucleation mode particles and aerosol pollution levels in Beijing

“…The growth stagnation and the disappearance of the particle mode from our observations suggest that the spatial extent of NPF is limited to nearby areas in the north-west direction. 52,65 Therefore, a possible explanation for these observations could be that practically no NPF occurs in the clean air masses descending from the mountainous area until they are mixed with precursor vapors emitted in the North China Plain.…”