珠三角地区大气新粒子生成事件的参数模拟与特征

Parameter simulation and characterizations of new particle formation events in different seasons in the Pearl River Delta region

针对珠三角大气复合污染典型地区新粒子生成事件,基于大气超级站不同季节3~1 000nm颗粒物数谱分布在线监测数据,采用气溶胶动力学模型模拟新粒子生成重要参数,分析不同季节新粒子生成事件的特征。研究结果如下。1)超级站新粒子生成事件的月平均发生频率为7%~23%,低于北京;新粒子生成速率为0.4~4.8个·cm-3·s^(-1),增长速率为3.0~12.0nm·h^(-1)。2)新粒子生成事件发生频率与新粒子生成速率、增长速率、可凝结蒸汽浓度及其产生速率在秋季均高于其他季节;珠三角地区秋季大气氧化性较强,光化学过程非常活跃,有利于新粒子生成与增长所需前体物的产生。3)高温、低湿、强辐射、高风速、低颗粒物质量浓度与高臭氧浓度等条件有利于新粒子生成事件的发生;较强的大气氧化性对珠三角地区新粒子生成事件的发生至关重要。研究结果可为深入了解大气气溶胶的演变过程及其环境效应提供参考。

Based on the online monitoring data for 3- 1 000 nm particle number size distributions in different seasons at the atmos- pheric supersite in the Pearl River Delta （PRD） region suffering typical complex air pollution, the important parameters of new particle formation （NPF） events were simulated with aerosol dynamic models, and their characterizations in different seasons were systematically analyzed. The results showed that： 1 ） The monthly average occurrence frequency of NPF events at the super site was 7%-23%, which was lower than that in Beijing. The new particle formation rates and growth rates were 0. 4 4. 8 cm ： s1 and 3.0 12.0 nm · h -1, respectively. 2） The occurrence frequency, new particle formation rate, growth rate, condensable vapor concentration and its production rate in autumn were higher than those in other seasons. In autumn of PRD region, the at mospheric oxidizability was strong, and the photochemical process was very active, favoring the precursor formation of new parti cle formation and growth. 3） The conditions with high temperature, low relative humidity, strong solar radiation, high wind speed, low particle mass concentrations, and high O：~ concentrations were favorable for NPF events. Strong atmospheric oxidiz- ability was crucial for the occurrence of NPF events in the PRD region. These results provide helpful information for revealing the evolution process and environmental effects of atmospheric aerosols.