气象因素对于华北平原秋冬季气溶胶物理特性的影响

The influence of meteorological factors on the physical characteristics of aerosols in the North China Plain during autumn and winter

大气气溶胶对空气质量、气候变化和人体健康等方面有重要影响.气溶胶物理特性决定了其辐射效应和成云能力.因此,针对气溶胶物理特性的观测研究对于准确理解和评估气溶胶环境气候效应至关重要.本研究基于2018年11月11日—12月19日和2019年9月26日—10月31日在中国华北平原农村站点开展的综合观测,探究了不同气象因子对气溶胶物理特性的影响.结果表明,相对湿度和风速变化对气溶胶光学特性和吸湿活化特性有重要影响.高相对湿度条件(RH=52%~89%)促进与液相反应相关的二次气溶胶生成,相对于低湿度条件(RH=29%~65%),气溶胶单次散射反照率(SSA)由0.75增加到0.83,60~200 nm粒径下的气溶胶吸湿性参数(κ)增加了约0.04,0.07%~0.81%过饱和比下的气溶胶活化率(f_(NCCN))相比低湿度条件下也增加了约0.2.高风速条件下采样点受区域传输影响更为强烈,当风速从2 m·s^(-1)增加到4.5 m·s^(-1)时,气溶胶后向散射比(HBF)增加了约36%,而f_(NCCN)则下降了约23%.此外,不同气团来源也将导致气溶胶各物理特性发生变化,当较清洁干燥的西北气团占主导时,颗粒物粒径较低,导致f_(NCCN)降低、HBF升高,而当污染程度高的西南气团占主导时,颗粒物粒径显著增加,f_(NCCN)随之增加、HBF则有所降低.

Atmospheric aerosols have significant impacts on air quality,climate change,and human health.The physical properties of aerosols determine their radiative effects and cloud-forming capabilities.Therefore,observational studies on aerosol physical properties are crucial for accurately understanding and assessing the environmental and climate effects of aerosols.In this study,we conducted comprehensive observations at a rural site in the North China Plain from November 11 to December 19,2018,and from September 26 to October 31,2019,to explore the influence of meteorological factors on aerosol physical properties.The results show that changes in relative humidity and wind speed have significant effects on the optical properties,hygroscopicity,and activation properties of aerosols.High relative humidity conditions(RH=52%~89%)promote secondary aerosol formation related to liquid-phase reactions.Compared to low humidity conditions(RH=29%~65%),the aerosol single scattering albedo(SSA)increased from 0.75 to 0.83,the aerosol hygroscopicity parameter(κ)in the 60~200 nm particle size range increased by about 0.04,and the aerosol activation rate(f_(NCCN))at 0.07%~0.81%supersaturation ratio also increased by about 0.2.Under high wind speed conditions,the sampling site is more strongly affected by regional transport.When the wind speed increases from 2 m·s^(-1)to 4.5 m·s^(-1),the aerosol backscattering ratio(HBF)increases by 36%,while f_(NCCN)decreases by 23%.Additionally,different air masses lead to variations in aerosol physical properties.Particle size decreases in the clean and dry air masses originated from northwest,resulting in lower f_(NCCN)and higher HBF.On the contrary,when the highly polluted southwestern air mass dominates,the increasing particle size leads to significant increases in f_(NCCN)and decreases in HBF.