Measured and modelled cloud condensation nuclei number concentration at the high alpine site Jungfraujoch
Measured and modelled cloud condensation nuclei number concentration at the high alpine site Jungfraujoch
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DOI：
10.5194/acp-10-7891-2010
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发表时间：
2010-01-01
影响因子：
6.3
通讯作者：
Baltensperger, U.
中科院分区：
文献类型：
--
作者：
Juranyi, Z.;Gysel, M.;Baltensperger, U.
大气气溶胶粒子能够充当云凝结核（CCN），因此对气候和水文循环非常重要，但其性质尚未完全了解。2008年5月，在瑞士少女峰（海拔3580米）的偏远高山研究站，测量了10种不同过饱和度（SS=0.12-1.18%）下的云凝结核数浓度。在本文中，我们提出了一个封闭的研究之间的测量和预测的云凝结核数浓度。在简化的科勒理论中，使用干数尺寸分布（扫描粒子迁移率大小仪，SMPS）和大量化学成分数据（气溶胶质谱仪，AMS和多角度吸收光度计，MAAP）进行CCN预测。CCN数浓度的预测值与实测值吻合得很好，相关性很强。一项敏感性研究表明，在少女峰的化学成分的时间变化可以忽略一个可靠的CCN预测，而它是重要的是要知道的平均化学成分。通过使用一个太低或太高的吸湿性参数CCN预测引入的准确的偏差进一步量化，并被证明是实质性的最低的过饱和度。尽管高的平均有机质量分数（类似于45%）在精细模式，没有迹象表明，表面张力显着降低在CCN活化点。吸湿性串联微分迁移率分析仪（HTDMA），AMS/MAAP，和CCN衍生的kappa值之间的比较表明，HTDMA测量可以用来确定颗粒吸湿性CCN预测所需的，如果没有合适的化学成分数据。
Atmospheric aerosol particles are able to act as cloud condensation nuclei (CCN) and are therefore important for the climate and the hydrological cycle, but their properties are not fully understood. Total CCN number concentrations at 10 different supersaturations in the range of SS=0.12-1.18% were measured in May 2008 at the remote high alpine research station, Jungfraujoch, Switzerland (3580 m a.s.l.). In this paper, we present a closure study between measured and predicted CCN number concentrations. CCN predictions were done using dry number size distribution (scanning particle mobility sizer, SMPS) and bulk chemical composition data (aerosol mass spectrometer, AMS, and multi-angle absorption photometer, MAAP) in a simplified Kohler theory. The predicted and the measured CCN number concentrations agree very well and are highly correlated. A sensitivity study showed that the temporal variability of the chemical composition at the Jungfraujoch can be neglected for a reliable CCN prediction, whereas it is important to know the mean chemical composition. The exact bias introduced by using a too low or too high hygroscopicity parameter for CCN prediction was further quantified and shown to be substantial for the lowest supersaturation.Despite the high average organic mass fraction (similar to 45%) in the fine mode, there was no indication that the surface tension was substantially reduced at the point of CCN activation. A comparison between hygroscopicity tandem differential mobility analyzer (HTDMA), AMS/MAAP, and CCN derived kappa values showed that HTDMA measurements can be used to determine particle hygroscopicity required for CCN predictions if no suitable chemical composition data are available.