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1.
Precipitation scavenging of aerosol particles is an important removal process in the atmosphere that can change aerosol physical and optical properties. This paper analyzes the changes in aerosol physical and optical properties before and after four rain events using in situ observations of mass concentration, number concentration, particle size distribution, scattering and absorption coefficients of aerosols in June and July 2013 at the Xianghe comprehensive atmospheric observation station in China. The results show the effect of rain scavenging is related to the rain intensity and duration, the wind speed and direction. During the rain events, the temporal variation of aerosol number concentration was consistent with the variation in mass concentration, but their size-resolved scavenging ratios were different. After the rain events, the increase in aerosol mass concentration began with an increase in particles with diameter 0.8 μm [measured using an aerodynamic particle sizer(APS)], and fine particles with diameter 0.1 μm [measured using a scanning mobility particle sizer(SMPS)]. Rainfall was most efficient at removing particles with diameter ～0.6 μm and greater than 3.5 μm. The changes in peak values of the particle number distribution(measured using the SMPS) before and after the rain events reflect the strong scavenging effect on particles within the 100–120 nm size range. The variation patterns of aerosol scattering and absorption coefficients before and after the rain events were similar, but their scavenging ratios differed, which may have been related to the aerosol particle size distribution and chemical composition. 相似文献
2.
The diffusion aerosol spectrometer for the measurements of particle size spectra and concentration levels is described. It includes three principal parts: (i) a block of diffusion batteries for measuring the particles, whose size does not exceed 0.15 μm, (ii) the particle amplifier for growing the particles passing through the diffusion batteries up to optically distinguishable sizes and (iii) the laser aerosol spectrometer, which counts the amplified particles and may also serve for independent measurements of particle size spectra within submicron size range. The tandem including: diffusion batteries+laser aerosol spectrometer allows for detecting particles of radius >3 nm at maximal concentration up to 2×104 particles/cm3. The tandem is managed either by PC or manually. The instrument is designed for studying aerosols in the atmosphere and for ecological measurements. 相似文献
3.
2008年北京奥运会期间大气气溶胶物理特征分析 总被引：5，自引：0，他引：5
应用MODIS卫星的气溶胶产品资料和地面的光学粒子计数器的资料,对比分析了北京地区2006、2007、2008年7～9月的气溶胶光学厚度、细粒子光学厚度、Angstrom指数、气溶胶粒子数浓度谱及体积谱,发现2008年北京奥运会期间(7月20日～9月20日)的气溶胶光学厚度比2006、2007年同期明显降低,气溶胶细模态光学厚度占总光学厚度的比上升,Angstrom指数上升,气溶胶细粒子数浓度没有明显相对变化,而粗粒子数浓度则减少约50%.利用大气标高,将MODIS反演的气溶胶柱的质量浓度转化为地面气溶胶质量浓度.用粒子计数器得到的体积谱,在假定气溶胶粒子密度的情况下,计算出其质量浓度.将这两种方法得到的气溶胶质量浓度与国家环境保护部公布的空气质量指数换算得到的可吸入颗粒物(PM10)质量浓度进行比较.结果表明:北京奥运期间空气质量总体达到了国家二级空气质量标准;与2006、2007年同期相比,2008年气溶胶PM10质量浓度明显下降,而这主要是由气溶胶粗粒子的减少引起的. 相似文献
4.
通过实验收集大气颗粒物，对南京地区大气气溶胶谱分布进行了描述，对气溶胶分布与相对湿度的相关性进行了探讨。建立了南京地区7—11月气溶胶化学组分的月平均模型，得出气溶胶等效复折射率的预测方法。结果表明：南京地区的大气气溶胶颗粒物，峰值粒径在80~100 nm范围，属于典型的城市型气溶胶。数浓度与相对湿度的相关性与季节和粒径大小有关，在6—9月，相对湿度与细粒子数浓度呈负相关，与粗粒子呈正相关，在10—11月相反，且易受极端天气影响。建立的干气溶胶等效复折射率月平均模型，结合湿度修正模型得到某一日的复折射率，与AERONET站点数据进行了对比，结果较为一致，误差范围在0~0.03。 相似文献
5.
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6.
An extensive field experiment for measurement of physical and chemical properties of aerosols was conducted at an urban site in the Chinese Academy of Meteorological Sciences (CAMS) in Beijing and at a rural site in Gucheng (GC), Hebei Province in December 2016. This paper compares the number size distribution of submicron particle matter (PM1, diameter < 1 μm) between the two sites. The results show that the mean PM1 number concentration at GC was twice that at CAMS, and the mass concentration was three times the amount at CAMS. It is found that the accumulation mode (100–850 nm) particles constituted the largest fraction of PM1 at GC, which was significantly correlated with the local coal combustion, as confirmed by a significant relationship between the accumulation mode and the absorption coefficient of soot particles. The high PM1 concentration at GC prevented the occurrence of new particle formation (NPF) events, while eight such events were observed at CAMS. During the NPF events, the mass fraction of sulfate increased significantly, indicating that sulfate played an important role in NPF. The contribution of regional transport to PM1 mass concentration was approximately 50% at both sites, same as that of the local emission. However, during the red-alert period when emission control took place, the contribution of regional transport was notably higher. 相似文献
7.
沙尘传输路径上气溶胶浓度与干沉降通量的粒径分布特征 总被引：1，自引：0，他引：1
利用2002年春季中国北京、青岛和日本福冈3个地区的分级气溶胶浓度资料,结合改进的Wil-liams模型,分析了沙尘传输路径上空气动力学直径≤11μm气溶胶(PM11)浓度和干沉降通量的粒径分布特征,并估算了黄海海域春季PM11的干沉降通量及不同粒径气溶胶的贡献。结果表明:3个地区PM11浓度粒径分布在非沙尘时期呈双峰分布,两个峰值分别出现在细颗粒(<2.1μm)部分和粗颗粒(2.1～11μm)部分;沙尘时期,3个地区PM11浓度粒径分布均趋于单峰分布,峰值位于粗颗粒部分,并且越靠近沙尘源地,这种趋势越明显。较强沙尘天气时期,粗颗粒部分的浓度峰值粒径从沙尘源地附近到黄海西岸、东岸呈降低趋势,但在一般沙尘天气时期,这种现象并不明显。沙尘时期和非沙尘时期,3个地区粗颗粒的干沉降通量均随粒径增加而增大,细颗粒的干沉降通量随粒径的变化不明显。虽然沙尘时期粗颗粒沉降通量较非沙尘时期有明显增加,但粗颗粒对PM11干沉降通量的贡献与非沙尘时期相比,并没有明显的变化。较强沙尘天气时期,3个地区粗颗粒的干沉降通量明显高于一般沙尘天气时期;细颗粒的干沉降通量较一般沙尘天气时期略有增加。黄海海域春季沙尘时期PM11的干沉降通量约为31.70～58.59mg.m-2.d-1,非沙尘时期约为8.33～15.94mg.m-2.d-1。粗颗粒是黄海海域春季PM11干沉降通量的主要贡献者,约占PM11干沉降通量的94.2%以上。 相似文献
8.
2016年11月13日在北京地区上空存在持续稳定的层状云天气背景下,利用飞机开展气溶胶粒径谱、化学组成、云滴谱等参量的垂直观测,研究该个例云底气溶胶的活化能力。结果表明:探测期间北京地区为轻度污染天气,地面气溶胶浓度(0.11~3 μm)达到4600 cm-3。云层高度为800~1200 m,云底气溶胶数浓度相对于近地面大幅度降低,有效粒径显著增大(0.3~0.6 μm)。同时,近地面气溶胶中疏水性的一次有机气溶胶贡献显著,而云底气溶胶中一次有机气溶胶的贡献大幅降低,无机组分和二次有机气溶胶的贡献明显增大,造成吸湿性参数κ由0.25(地面)增大至0.32(云底)。云中气溶胶和云滴的谱分布衔接较好,且两者的数浓度之和与云底气溶胶浓度一致,可分别代表未活化和已活化的粒子。基于云底气溶胶粒径谱和吸湿性参数计算得到不同过饱和比下云凝结核的活化率,通过与云中观测结果对比,反推得到云底过饱和度约为0.048%。 相似文献
9.
南京地区冬季大气冰核特征及其与气溶胶关系的研究 总被引：6，自引：1，他引：5
2011年11月15日～12月2日期间对南京地区近地面大气气溶胶和冰核进行了同步观测,综合分析了 冰核浓度的特征及其与气溶胶粒子浓度的关系。结果表明:活化温度Ta为-20℃,水面过饱和度为1%时,南京地区冰核浓度NIN为0.352 L-1,与0.01～10 μm气溶胶数浓度比值仅为4×10-8。冰核活化温度越低,湿度越大,冰核浓度越高。雾和降雨对冰核都有明显的清除作用。对比不同气团对南京地区冰核的影响发现,偏东方向的污染气团中冰核以及气溶胶的浓度最高,但是来自西北地区的气团中冰核占气溶胶的比例最高,这可能是由于冰相核化能力较强的沙尘气溶胶导致的。分析冰核与不同粒径段气溶胶的相关性发现,较大粒径气溶胶的表面积浓度与冰核相关性更高,本文也得到了由活化温度Ta和粒径大于0.5 μm气溶胶数浓度N0.5～10 μm共同计算冰核浓度的经验公式。 相似文献
10.
M. Vana E. Tamm U. Hrrak A. Mirme H. Tammet L. Laakso P.P. Aalto M. Kulmala 《Atmospheric Research》2006,82(3-4):536
In this work, the charging state of atmospheric nanoparticles was estimated through simultaneous measurements of aerosol size distribution and air ions mobility distribution with the aim to elucidate the formation mechanisms of atmospheric aerosols. The measurements were performed as a part of the QUEST 2 campaign at a boreal forest station in Finland. The overlapping part of the measurement ranges of the particle size spectrometers and air ion mobility spectrometers in the mass diameter interval of 2.6–40 nm was used to assess the percentage of charged particles (charging probability). This parameter was obtained as the slope of the linear regression line on the scatterplot of the measured concentrations of total (neutral + charged) and charged particles for the same diameter interval. Charging probabilities as a function of particle diameter were calculated for different days and were compared with the steady state charging probabilities of the particles in the bipolar ion atmosphere. For the smallest particles detectable by the particle size spectrometers (2.6–5 nm), the high percentages of negatively charged particles were found during the nanometer particle concentration bursts. These values considerably exceeded the values for the steady charging state and it was concluded that negative cluster ions preferably act as condensation nuclei. This effect was found to be the highest in the case of comparatively weak nucleation bursts of nanoparticles, when the rate of the homogeneous nucleation and the concentration of freshly nucleated particles were low. The nucleation burst days were classified according to the concentration of the generated smallest detectable new particles (weak and strong bursts). Approximately the same classification was obtained based on the charge asymmetry on particles with respect to the charge sign (polarity). The probabilities of negative and positive charge on the particles with the diameter of 5–20 nm were found to be nearly equal and they approximately agree with the values corresponding to the steady state charge distribution for negative particles known from lab experiments. It means that the steady charging state was reached during the growing time of particles up to 5 nm. The natural charging state of particles with a diameter between 2.5 and 4.5 nm was estimated by means of a special DMPS setup. Results were found to be in good correlation with the data by the particle size spectrometers and air ion mobility spectrometers. 相似文献
11.
气溶胶与云的垂直分布特征是气溶胶间接气候效应关注的重点。基于2018年7—8月华北中部6架次飞机观测数据,研究气溶胶和云滴的垂直和水平分布特征。结果表明:华北中部780~5687 m高度内气溶胶数浓度( Na )平均值为821.36 cm-3,最大量级可达到104 cm-3,云中气溶胶数浓度(Nacc)占总颗粒浓度的80%以上,表明细颗粒占大多数,气溶胶粒子算术平均直径( Dm )平均值为0.12~0.52 μm;大气层结对气溶胶垂直分布影响较大,逆温阻挡气溶胶垂直输送,高空(高度2000 m以上) Dm 的垂直分布受到相对湿度影响较大; Na 和 Dm 在垂直方向波动较大,水平方向波动较小;低层云中云滴数浓度(Nc)较大、液态水含量(L)较小,而中层和高层云中Nc较小、L较大,Nc和云滴有效半径(Re)的概率密度函数均为双峰型分布,L的概率密度函数为单峰型分布;气溶胶数浓度谱基本呈现多峰型分布,而云滴数浓度谱多呈现单峰型分布。 相似文献
12.
Masaharu Watanabe Yasunobu Iwasaka Takashi Shibata Masahiko Hayashi Motowo Fujiwara Roland Neuber 《Atmospheric Research》2004,69(3-4):199-215
Balloon-borne aerosol measurements were performed with an optical particle counter between 1994 and 2000 at Ny-Ålesund (79°N), Svarbard. Throughout the observation period, continuous decay was found in the concentrations of particles with 0.4–0.6 μm in radius in the Arctic stratosphere, suggesting that Pinatubo aerosols remained even at the end of the 1990s. The decay rate was clearly higher for larger particle sizes, and higher at higher altitude (e-folding time of 970–526 days), suggesting a gravitational sedimentation effect. For smaller particles with R<0.4 μm, slight increases in concentration with time were found, which agreed with the measurements at mid-latitude. The sulfate mass mixing ratio in the Arctic stratosphere before 1998 showed values higher than those at middle latitude, while values were almost the same in both regions after 1998. A possible explanation of the latitudinal difference is a time lag (of 0.5–1 year) in the arrival of Pinatubo aerosols in the Arctic. 相似文献
13.
14.
NAQPMS+APM模式对北京冬季细粒子谱分布演变特征的数值模拟 总被引：1，自引：1，他引：0
利用包含详细微物理动力学机制的NAQPMS+APM(Nested Air Quality Prediction Modeling System with Advanced Particle Microphysics)模式,对北京城市大气2006年1月15日至2月13日期间的粒子数浓度谱分布进行了模拟,模式模拟结果合理,能够很好地再现北京城市大气细粒子的数浓度谱分布演变特征。分析表明,北京冬季大气新粒子形成事件频发,核化作用使核模态粒子数浓度急剧升高;污染累积时,积聚模态粒子数浓度显著增大,而核模态粒子数浓度很小,粒子谱分布向大粒子端移动;重污染期间,粒子微物理混合作用强烈,二次成分在一次粒子上的附着使一次粒子粒径显著增大,二次成分可使一次粒子粒径增大50%以上,积聚模态的二次粒子与一次粒子共同促进了污染的形成。在北京及其近周边区域,北京南部和河北南部一次粒子数量多,占据主导地位,而在河北北部二次粒子则占主导地位。 相似文献
15.
Characterisation of Soot Emitted by Domestic Heating,Aircraft and Cars Using Diesel or Biodiesel 总被引：1，自引：0，他引：1
The characterisation of aggregates, like soot, firstly requires the determination of the size distribution of the primary
particles. The primary particle size of combustion generated aggregates depends upon the combustion environment and the formation
conditions, such as temperature, pressure and fuel-to-air ratio, among others. Since the combustion characteristics are different
in the different types of burners, the characterisation of primary particles may offer the possibility to distinguish soot
from different sources. In this paper, we present the signature of the primary particles and the aggregates of soot emitted
by cars using diesel or biodiesel, by domestic heating, and by aircraft exhausts, which can be considered as the major sources
as derived from measurements on transmission electron micrographs. The size distributions of all aggregates types with different
aerodynamic diameter were log-normal and quasi-monodisperse. The size distribution of the primary particles for soot emitted
by different sources showed minor differences. However, a comparison between the diameter of the primary particles and those
obtained using a standard method for carbon black revealed discrepancies. The median diameter of the primary particles was
combined with the median number of primary particles in an aggregate to calculate the relative particle surface area available
for adsorption. In a similar way, the relative specific surface area was determined. The surface area was measured using the
Brunauer-Emmett-Teller (B.E.T.) nitrogen adsorption method and the relative surface area available for adsorption was calculated. 相似文献
16.
The change of the chemical composition of the near-ground level atmospheric aerosol was studied during two summer episodes by a Lagrangian type of experimental approach. Bulk and single-particle chemical analyses of ions and elements in the particulate phase were deployed. N(-III) and N(V) components were also measured in the gas-phase. The measurements were completed by particle size distributions.Secondary inorganic aerosols (SIA) and fine particles of ≈0.2–0.4 μm size were still elevated 50 km downwind of the city. The direct comparison of transport over the city in contrast to transport over the surrounding areas showed that SIA was formed from emission from the city within less than 3 h. Relative increases, i.e., enrichment during transport were observed for primary and secondary aerosol components. The degree of mixing on the individual particle level increased significantly during transport in the area. In particular, newly emitted carbonaceous particles became internally mixed within hours with pre-existing sulphate particles. Mostly due to secondary aerosol formation the average particle size (mass median diameter) of major constituents of the aerosol was significantly decreased while being transported over 13 h. Given recent insights which link fine particles number and mass concentrations with health risks, the results suggest that rural populations in areas which frequently are located within an urban plume might run an elevated health risk relative to populations in areas not affected by urban plumes. 相似文献
17.
A multifunctional HTDMA system with a robust temperature control 总被引：3，自引：0，他引：3
The hygroscopicity of atmospheric aerosols significantly influences their size distribution,
cloud condensation nuclei ability, atmospheric residence time, and climate forcing. In order to investigate
the hygroscopic behavior of aerosol particles and serious haze in China, a Hygroscopic Tandem Differential
Mobility Analyzers (HTDMA) system was designed and constructed at Fudan University. It can function as a
scanning mobility particle sizing system to measure particle size distribution in the range of 20--1000 nm
in diameter, as well as a hygroscopicity analyzer for aerosol particles with diameters between 20--400 nm
in the range of 20%--90% RH (relative humidity). It can also measure the effect of uptake of inorganic acids
or semi-VOCs on the hygroscopic behavior of aerosols, such as typical inorganic salts in atmospheric dust or
their mixtures. The performance tests show that the system measured particle size of the standard polystyrene
latex spheres (PSLs) is 197 nm, which is in excellent agreement with the certified diameter D=199±6 nm, as
well as a standard deviation of the repeated runs SD=8.9x10-4. In addition, the measured hygroscopic
growth factors of the model compounds, (NH4)2SO4 and NaNO3, agree with the Kohler theoretical
curves. The results indicate that the HTDMA system is an excellent and powerful tool for studying the
hygroscopic behavior of submicron aerosols and meets the demand required for laboratory research and
fieldwork on atmospheric aerosols in China. 相似文献
18.
T. Sugita Y. Kondo M. Koike M. Kanada N. Toriyama H. Nakajima T. Deshler R. Imasu 《Journal of Atmospheric Chemistry》1999,32(1):183-204
A new balloon-borne optical particle counter has been developed to make in situ measurements of stratospheric aerosols. The intensity of light scattered at 60° from the forward direction by individual particles is measured. Aerosol number concentrations in seven size channels can be inferred. The counter has been calibrated using polystyrene and polyvinyl toluene latex spheres. There is good agreement between measured and calculated individual pulse intensities for aerosol with radii from 0.16 to 2.6 µm. The size resolution is limited by broadening of the pulse count/pulse height spectrum, arising mainly from the photoelectron statistics of photomultipliers. Stratospheric aerosol measurements have been made using this instrument at Kiruna (68°N, 21°E), Sweden, in February 1995, and at Aire sur l'Adour (44°N, 0°W), France, in 1992, 1993, and 1994. The uncertainties in the measurements are discussed. The retrieved aerosol concentrations and size distributions are presented, and shown to be broadly consistent with measurements made by the University of Wyoming optical particle counter. 相似文献
19.
利用2011年和2013年夏秋季在青藏高原中东部开展的11架次气溶胶特征飞机观测数据,分析气溶胶数浓度、数谱及核化相关特征。结果表明:受天气系统、地形和地表影响,观测区内气溶胶数浓度（Na）和体积直径（Dv）的垂直和水平分布差异较大,Na呈西北高、东南低,Dv低层大、高层小,局地中高层有沙尘。格尔木盛行东风时,云降水对低层气溶胶有清除作用,Na和Dv明显降低,6.2 km高度和7.2~7.4 km高度的中高空受高原大风或对流影响形成沙尘;盛行西风时,低层Dv以0.5~0.8 μm为主,随高度升高和风速增大Na升高,Dv变幅较小,6.2 km高度也有沙尘;不同天气系统影响下6.5 km高度以上均输入亚微米颗粒,Na达5×103 cm-3,8.0 km高度盛行东风时比西风时Na更高,Dv更小,谱垂直分布也有以上特征,整层输入以偏北或偏西路径为主。不同过饱和度测量云凝结核数浓度（Nccn）表明,除格尔木6.0 km高度以下核化率（Nccn/Na）在21%~47%外,其他观测区平均核化率介于1%~16%,6.0~8.5 km高度的核化率总体偏低;当Na增加时核化率明显下降,且过饱和度1%~2%,-15~-5℃层或粒径1~3 μm时的核化率相对偏高。 相似文献
20.
庐山一次积冰天气过程冻雨滴谱及下落末速度物理特征个例研究 总被引：2，自引：1，他引：1
利用PARSIVEL激光雨滴谱仪和自动气象站观测资料及MICAPS数据,对2014年2月7~15日庐山地区积冰天气期间持续时间在5 h以上的2次冻雨过程[2月10日（个例1）和2月13日（个例2）]降水谱分布特征及下落末速度粒径分布进行研究。所观测到的两次个例均是以冻雨为主体的混合相态降水,下落末速度粒径分布偏离G-K曲线,与常规液态降水存在差异,低落速的冻雨滴随降水过程会逐渐向冰粒和干雪转化。结果表明:（1）个例1总降水粒子谱谱宽大于个例2,但峰值数密度比个例2小:个例1谱宽为10 mm,个例2谱宽为4.25 mm,两者峰值粒径均为0.5 mm;个例1降水粒子谱宽为干雪>冻雨>冰粒,个例2降水粒子谱宽为冻雨>干雪>冰粒。（2）Gamma分布更适合描述混合相态降水粒子谱以及冻雨滴谱,个例1中总降水粒子谱Gamma分布为:N（D）=20D-3.61exp（-0.08D）,冻雨Gamma分布:N（D）=76D-2.18exp（-1.11D）;个例2中总降水粒子谱Gamma分布为:N（D）=30D-4.68exp（-0.75D）,冻雨Gamma分布:N（D）=30D-4.67exp（-0.75D）。（3）混合相态降水因混有干雪或冰粒而使得下落末速度粒径谱分布表现出不同程度地向大粒径小落速方向或小粒径大落速方向延展的趋势,这为今后依据下落末速度粒径谱区分同时期降水类型提供了新的思路。 相似文献