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| Characterization of new particle formation event in the rural site of Sichuan Basin and its contribution to cloud condensation nuclei |
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Abstract To investigate the formation mechanism of complex air pollution in Chengdu-Chongqing district, field campaign was conducted at a rural size Ziyang during the winter time of 2012 to study the new particle formation (NPF) events and their impact to cloud condensation nuclei (CCN) in the high polluted atmosphere background. Particle number size distribution and the number of CCN were measured. The gaseous sulfuric acid concentration was estimates based on the mixing ratio of SO2 and photolysis rate (JO1D). During the whole champion (Dec 5th, 2012 to Jan 5th, 2013), the particle number concentration was high, with an average of (16072±9713)cm-3. The dominate mode was the accumulation mode, accounting for 46% of the total particle number concentration, indicating dominant secondary formation. This ratio was higher than that of rural sites and background sites of Beijing, Shanghai, Guangzhou, the Pearl River Delta, and the Yangtze River Delta. The coagulation condensation sink (CS), indicating preexisting particle concentration was high [(4.3 ± 3.6) × 10- 2s-1]. However, seven NPF events were measured, accounting for 23% of the observed days. Compared with the results of other studies, the particle formation rate was slightly higher [(5.2 ± 1.4)cm-3s-1], and the particle growth rate [(3.6 ± 2.5)nm/h] was lower. NPF events significantly contributed to the number concentration of CCN. After NPF events, the average growth rate of the number concentration of CCN was 19%.
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Received: 12 February 2014
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