Measurements of humidified particle number size distributions in a Finnish boreal forest: derivation of hygroscopic particle growth factors
Measurements of humidified particle number size distributions in a Finnish boreal forest: derivation of hygroscopic particle growth factors
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芬兰北方森林中加湿颗粒数量尺寸分布的测量：吸湿颗粒生长因子的推导
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发表时间：
2009
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通讯作者：
M. Boy
中科院分区：
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作者：
W. Birmili;K. Schwirn;A. Nowak;T. Petäjä;J. Joutsensaari;D. Rose;A. Wiedensohler;K. Hämeri;P. Aalto;M. Kulmala;M. Boy
2004年5月至7月，在芬兰的大气研究站SMEAR II对干态和湿态大气颗粒的大小分布进行了表征。在控制相对湿度高达90%的情况下，通过两种尺寸范围互补的仪器（HDMPS；纳米HDMPS），将颗粒分类在3至800纳米之间的尺寸范围内。采用求和法，通过比较干燥和湿化粒径分布，得出粒径在70 ~ 300 nm之间的描述性吸湿生长因子（DHGF）。在90%相对湿度条件下，累积态DHGF均值在1.25 ~ 1.45之间，艾特肯态DHGF均值在1.20 ~ 1.25之间，成核态DHGF均值在1.15 ~ 1.20之间。由于该方法的高尺寸分辨率，可以有效地确定DHGF在艾特肯模式和积累模式之间的转变，这反映了可溶性分数的差异。对于累积模式，实验DHGFs与由原位化学成分测量初始化的简单生长模型计算的DHGFs进行了比较，得出的最大偏差约为0.1。DHGF的变化只能不完全地与气象因素联系起来。推导了DHGF作为颗粒直径和相对湿度函数的实用参数化，并随后用于研究均匀混合边界层中冷凝汇参数（CS）作为高度函数的敏感性。
Dry and humidified size distributions of atmospheric particles were characterised at the atmospheric research station SMEAR II, Finland between May and July 2004. Particles were classified in a size range between 3 and 800 nm at controlled relative humidities up to 90% by two instruments complementary in size range (HDMPS; Nano-HDMPS). Using the summation method, descriptive hygroscopic growth factors (DHGF) were derived for particle diameters between 70 and 300 nm by comparing dry and humidified size distributions. At 90% relative humidity, DHGF showed mean values between 1.25 and 1.45 in the accumulation mode, between 1.20 and 1.25 in the Aitken mode, and between 1.15 and 1.20 in the nucleation mode. Due to the high size resolution of the method, the transition in DHGF between the Aitken and accumulation modes, which reflects differences in the soluble fraction, could be pinpointed efficiently. For the accumulation mode, experimental DHGFs were compared to those calculated from a simplistic growth model initialised by in-situ chemical composition measurements, and yielded maximum deviations around 0.1. The variation in DHGF could only imperfectly be linked to meteorological factors. A pragmatic parameterisation of DHGF as a function of particle diameter and relative humiditity was derived, and subsequently used to study the sensitivity of the condensational sink parameter (CS) as a function of height in a well-mixed boundary layer.