Predicting hygroscopic growth using single particle chemical composition estimates
Predicting hygroscopic growth using single particle chemical composition estimates
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DOI：
10.1002/2014jd021888
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发表时间：
2014-08
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通讯作者：
R. Healy;G. Evans;Michael Murphy;Z. Jurányi;T. Tritscher;M. Laborde;E. Weingartner;M. Gysel;L. Poulain;K. Kamilli;A. Wiedensohler;I. O'Connor;E. McGillicuddy;J. Sodeau;J. Wenger
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作者：
R. Healy;G. Evans;Michael Murphy;Z. Jurányi;T. Tritscher;M. Laborde;E. Weingartner;M. Gysel;L. Poulain;K. Kamilli;A. Wiedensohler;I. O'Connor;E. McGillicuddy;J. Sodeau;J. Wenger
在法国巴黎收集的单粒子质谱数据已用于预测单粒子水平的吸湿增长。黑碳，有机气溶胶，铵，硝酸盐和硫酸盐存在于每个粒子的质量分数估计使用单粒子质谱仪和散装气溶胶化学成分测量的组合。然后应用Zdanovskiii-Stokes-罗宾逊（ZKR）方法根据这些质量分数估计值预测吸湿生长因子。具有高黑碳质量分数和低无机离子质量分数的较小颗粒表现出最低的预测生长因子，而具有高无机离子质量分数的较大颗粒表现出最高的生长因子。计算亚饱和相对湿度（90%）的生长因子，以便与吸湿串联微分迁移率分析仪测量结果进行比较。发现110、165和265 nm颗粒的平均预测和测量吸湿生长因子在6%以内一致。通过提供额外的化学混合状态信息，基于单个颗粒的BRR吸湿性估计值优于基于散装气溶胶组成的吸湿性估计值。外部混合可以通过检查预测的吸湿生长因子分布来确定给定直径的颗粒。使用这种方法，110 nm和265 nm的颗粒被发现主要是内部混合，然而，外部混合的165 nm的颗粒时，观察到周期性的薄涂层和厚涂层的黑碳颗粒同时检测。单粒子分辨的化学信息将有助于旨在约束云凝结核活动和吸湿增长的建模工作。
Single particle mass spectral data, collected in Paris, France, have been used to predict hygroscopic growth at the single particle level. The mass fractions of black carbon, organic aerosol, ammonium, nitrate, and sulphate present in each particle were estimated using a combination of single particle mass spectrometer and bulk aerosol chemical composition measurements. The Zdanovskii‐Stokes‐Robinson (ZSR) approach was then applied to predict hygroscopic growth factors based on these mass fraction estimates. Smaller particles with high black carbon mass fractions and low inorganic ion mass fractions exhibited the lowest predicted growth factors, while larger particles with high inorganic ion mass fractions exhibited the highest growth factors. Growth factors were calculated for subsaturated relative humidity (90%) to enable comparison with hygroscopic tandem differential mobility analyzer measurements. Mean predicted and measured hygroscopic growth factors for 110, 165, and 265 nm particles were found to agree within 6%. Single particle‐based ZSR hygroscopicity estimates offer an advantage over bulk aerosol composition‐based hygroscopicity estimates by providing additional chemical mixing state information. External mixing can be determined for particles of a given diameter through examination of the predicted hygroscopic growth factor distributions. Using this approach, 110 nm and 265 nm particles were found to be predominantly internally mixed; however, external mixing of 165 nm particles was observed periodically when thinly coated and thickly coated black carbon particles were simultaneously detected. Single particle‐resolved chemical information will be useful for modeling efforts aimed at constraining cloud condensation nuclei activity and hygroscopic growth.