黄山大气气溶胶新粒子生长特性观测分析

利用2012年9月22日~10月28日黄山地区大气气溶胶、二氧化硫和臭氧观测数据,结合气象数据,分析气溶胶新粒子的生成-增长特征.分析发现,在33个有效观测日中,有新粒子生成-增长的观测日占总数的18.2%,其中晴天的发生频率为37.5%,新粒子生成-增长都开始于晴天上午,与无新粒子观测日相比,太阳辐射量、风速、SO2及O3浓度较高,环境温度和相对湿度较低.气溶胶新粒子的增长具有由小及大的特点,核模态气溶胶粒子(10~20nm)数浓度最先增加,爱根核模态粒子(20~50nm)数浓度随着时间推移逐渐增大,但浓度峰值依次下降,平均增长率为3.58nm/h.SO2浓度先于核模态气溶胶数浓度到达峰值,其氧化后的产物H2SO4为新粒子的核化提供前体物,并且参与新粒子的增长过程,当SO2浓度较低时,不会发生新粒子生长事件.

Observation of new particle formation and growth on Mount Huang

Growth of newly formed particles on Mount Huang in eastern China was investigated using the measured aerosol particle data, trace gas and meteorology data over the period from 22 September to 28 October, 2012. The new particle formation (NPF) events appeared on 6 out of 33 days, occurring before the noon of sunny days. Moreover, the occurrence frequency of the NPF events during sunny days was 37.5%. Compared with other days (non-NPF days), solar radiation, wind speed, SO2 and O3 concentrations were higher in NPF days on average with lower temperature and relative humidity (RH). The nucleation mode particle (10~20nm in diameters) concentrations increased first, and then the Aiken nuclei mode particle concentrations (20~50nm in diameters) increased over time. However, the peaks of large aerosol particle concentration were lower. The mean growth rate (GR) of the newly formed aerosol particles was estimated as 3.58nm/h. SO2 concentration reached the peak faster than nucleation mode particle number concentration does, and the oxidation of SO2 produced H2SO4 which was thought to participating in the particle nucleation as a kind of precursor. So the nucleation won’t appear under low concentration of SO2 even on sunny days.