Black carbon aerosol mixing state, organic aerosols and aerosol optical properties over the United Kingdom
Black carbon aerosol mixing state, organic aerosols and aerosol optical properties over the United Kingdom
复制标题
DOI：
10.5194/acp-11-9037-2011
复制
发表时间：
2011-09
影响因子：
6.3
通讯作者：
G. McMeeking;W. Morgan;M. Flynn;E. Highwood;K. Turnbull;J. Haywood;H. Coe
中科院分区：
文献类型：
--
作者：
G. McMeeking;W. Morgan;M. Flynn;E. Highwood;K. Turnbull;J. Haywood;H. Coe
抽象。黑碳气溶胶吸收阳光，从而导致正辐射强迫和气候变暖，并通过对呼吸系统的影响人类健康。BC与其他气溶胶物种的混合状态，特别是内部/外部混合的程度，已被强调为评估其辐射强迫及其气候影响的主要不确定性，但很少有混合状态的现场观测。我们提出了空中单粒子烟尘光度计（SP2）测量难熔BC（rBC）的质量浓度和混合状态，再加上气溶胶的组成和光学特性测量在英国的城市羽流和区域污染。所有的数据都是使用英国的BAe-146-301大型大气研究飞机（ARA）上的仪器获得的，该飞机由机载大气测量设施（FAAM）运营。我们使用气溶胶质谱仪（AMS）测量亚微米气溶胶组成，并使用正矩阵分解来分离烃类（HOA）和含氧有机气溶胶（OOA）。我们发现了一个更高的数量分数的厚涂层rBC颗粒在空气质量与大OOA相对于HOA，更高的臭氧-氮氧化物（NOx）的比率和大浓度的总亚微米气溶胶质量相对rBC质量浓度。更多的臭氧和OOA丰富的空气质量与来自欧洲大陆的运输，而从英国城市的羽流有较高的HOA和NOx和较少的厚涂层rBC颗粒。我们没有观察到任何显着变化的rBC质量吸收效率计算的rBC质量和光吸收系数测量的颗粒烟尘吸收光度计，尽管观察到显着变化的气溶胶组成和rBC混合状态。光散射和吸收对总消光的贡献（由单次散射系数（SSA）量化）确实因不同的空气质量而变化，与区域气溶胶相比，在城市羽流中观察到的SSA较低（0.85对0.9-0.95）。我们将这些差异归因于相对快速形成的二次气溶胶的存在，主要是OOA和硝酸铵，这必须考虑到在辐射强迫计算。
Abstract. Black carbon (BC) aerosols absorb sunlight thereby leading to a positive radiative forcing and a warming of climate and can also impact human health through their impact on the respiratory system. The state of mixing of BC with other aerosol species, particularly the degree of internal/external mixing, has been highlighted as a major uncertainty in assessing its radiative forcing and hence its climate impact, but few in situ observations of mixing state exist. We present airborne single particle soot photometer (SP2) measurements of refractory BC (rBC) mass concentrations and mixing state coupled with aerosol composition and optical properties measured in urban plumes and regional pollution over the United Kingdom. All data were obtained using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM). We measured sub-micron aerosol composition using an aerosol mass spectrometer (AMS) and used positive matrix factorization to separate hydrocarbon-like (HOA) and oxygenated organic aerosols (OOA). We found a higher number fraction of thickly coated rBC particles in air masses with large OOA relative to HOA, higher ozone-to-nitrogen oxides (NO x ) ratios and large concentrations of total sub-micron aerosol mass relative to rBC mass concentrations. The more ozone- and OOA-rich air masses were associated with transport from continental Europe, while plumes from UK cities had higher HOA and NO x and fewer thickly coated rBC particles. We did not observe any significant change in the rBC mass absorption efficiency calculated from rBC mass and light absorption coefficients measured by a particle soot absorption photometer despite observing significant changes in aerosol composition and rBC mixing state. The contributions of light scattering and absorption to total extinction (quantified by the single scattering albedo; SSA) did change for different air masses, with lower SSA observed in urban plumes compared to regional aerosol (0.85 versus 0.9–0.95). We attribute these differences to the presence of relatively rapidly formed secondary aerosol, primarily OOA and ammonium nitrate, which must be taken into account in radiative forcing calculations.