【作者】 秦彦硕；

【导师】 银燕；

【作者基本信息】 南京信息工程大学 ， 大气物理学与大气环境， 2012， 硕士

【摘要】 气溶胶粒子的尺度分布、化学组分和混合状态都会对云微物理特征产生影响。本文以黄山地区为例,首先分析了于2011年6-7月在黄山顶取得的气溶胶的离子成分及可能来源,然后利用多化学组分气溶胶绝热气块分档云模式,结合云微物理参数观测资料,模拟分析了气溶胶粒子的吸湿增长特性以及对云凝结核和云微物理特征的影响。黄山观测期间温度较高、风速较小,且没有有效降水情况下,气溶胶质量浓度将迅速增加。气溶胶中水溶性成分占总气溶胶质量浓度的34.2%,含量最高的阴离子是SO42-(12.3μg/m3)、NO3-(2.9μg/m3),阳离子为Ca2+(2.1μg/m3)、NH4+(1.8μg/m3),有机酸占了11.37%。从后向轨迹分析结果看,气溶胶化学成分主要受北方大陆(35%)、局地污染(47%)及西南大陆气团(18%)影响。其中局地污染气团造成气溶胶可溶性组分的质量浓度最大(21μg/m3),这与低压系统控制及地面风速较低等气象因素有密切关系。在实际观测资料基础上,模式中采用的初始谱即同期WPS测得气溶胶谱。模拟分析不同气团影响下黄山实际气溶胶吸湿特性,发现海洋混合型气溶胶具有吸湿因子最高,Gf为1.98(相对湿度90%),城市型气溶胶吸湿性次之(Gf为1.95),含沙尘等不可溶性物质较多的气溶胶吸湿性最差(Gf为1.91)。气溶胶组分对云凝结核模拟值和观测值的差异受天气状况影响较大。较低的过饱和度下,模拟值高于晴天和雨天观测CCN值,低于雾天CCN观测值；而过饱和度大于0.6%时,实际多组分气溶胶模拟CCN值约为晴天观测值3倍左右,和雾天观测值类似。在气溶胶谱一定时,不同天气形势影响下,气溶胶的化学组分随尺度分布不同,对气块的最大过饱和度和气溶胶临界过饱和度产生不同的影响,进而活化出不同云滴数浓度和云滴谱。多组分气溶胶模拟的云滴数目和实际观测的量级均处于102个/cm3。气块上升速度低于0.7m/s时,含有较多不可溶物质的气溶胶对云滴数浓度的影响较大；上升速度大于0.7m/s时,气块中可凝结水增多,海盐NaCl对云滴数浓度增加的效果更显著。同一上升速度下实际多组分气溶胶模拟云滴数较纯硫酸铵多,主要体现在云滴谱第一个峰值3.0μm之前；造成云滴谱较窄,其中北方气团方案对于云滴最大粒径仅为9.92μm,变窄的程度最显著,同时纯硫酸铵气溶胶模拟云滴最大粒径为10.31μm。模拟的云滴谱与雾滴谱的观测值相比发现,液滴处于4-5μm粒径段模拟的云滴数和观测值处于一个数量级范围。更多还原

【Abstract】 Recent studies showed that, the aerosol size spectra, chemical composition and mixed state will have an impact on the cloud microphysical characteristics. The aerosol components and cloud microphysical parameters were measured at a high-altitude background station on the summit of Mt. Huang from June to July2011, and were used as input to a multi-chemical-component (MCC) bin-resolved cloud parcel model to investigate the influence of MCC aerosols on hygroscopic growth, CCN and cloud microphysics.During the observation period, aerosol mass concentration at Mt. Huang will increase rapidly with high temperature, low wind and no effective precipitation. The aerosol water-soluble ion accounts for34.2%of the total mass concentration. The average SO42-anion concentration (12.3μg/m3) is the highest, followed by NO3-(2.9μg/m3). The average cation concentration is Ca2+and NH4+were2.1μg/m3and1.8μg/m3respectively. Organic acid accounts for11.37%of the water-soluble composition. The results from back trajectory cluster and aerosol ionic composition analysis show that three types of air masses affected the chemical composition of aerosol particles, including the northern continental (35%), local polluted (47%), and southwest air mass (18%). The highest aerosol mass concentration (21μg/m3) caused by local pollution, which is closely related to the low voltage system, the lower surface wind speed and other meteorological factor.Based on the actual observation data, the initial aerosol spectrum in the model is measured by WPS in the same period. Numerical simulation results show that the hygroscopic properties of MCC aerosol at Mt. Huang varied with the air mass. The hygroscopic growth factor of mixed aerosol is highest (Gf=1.98, RH=90%), followed by urban aerosol (Gf=1.95, RH=90%) and inclusion of insoluble component CaCO3caused by the northern continental air mass (Gf=1.91, RH=90%).Under different saturation simulated values and observed values are affected by weather conditions. When super saturation is lower, the CCN value simulated is higher than the sunny and rainy days observing CCN value, below the fog CCN observations. When super saturation is greater than0.6%, the CCN value simulated by MCC aerosol is about sunny days observation value of3times, and similar to observations in the fog.Numerical simulation results show that the effects of aerosol chemical compositions on cloud microphysical processes varied with weather conditions for the same aerosol distribution. Order of magnitude of the CDNC observation and simulated by the MCC aerosol are in the102个/cm3. It is also shown that inclusion of insoluble component CaCO3has more significant influence on CDNC when the updraft velocity is lower than0.7m/s; otherwise, NaCl dominated droplet activation process with increased condensable water. MCC aerosols led to higher cloud droplet number concentration (CDNC) than pure ammonium-sulfate aerosols under the same updraft velocity mainly represented as more droplets with sizes less than3.0μm. The MCC aerosols resulted in relatively narrow cloud droplet spectrum, especial in the northern continental air mass case (max droplet radius9.92μm), than pure ammonium-sulfate aerosols(max radius10.3μm). Compared with the observed values, the simulation of particle in4-5μm size is with the same order of magnitude.更多还原