Aerosol activation characteristics and prediction at the central European ACTRIS research station of Melpitz, Germany
Aerosol activation characteristics and prediction at the central European ACTRIS research station of Melpitz, Germany
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DOI：
10.5194/acp-22-15943-2022
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发表时间：
2022-12
影响因子：
6.3
通讯作者：
Yuan Wang;S. Henning;L. Poulain;Chunsong Lu;F. Stratmann;Yuying Wang;S. Niu;M. Pöhlker;H. Herrmann;A. Wiedensohler
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文献类型：
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作者：
Yuan Wang;S. Henning;L. Poulain;Chunsong Lu;F. Stratmann;Yuying Wang;S. Niu;M. Pöhlker;H. Herrmann;A. Wiedensohler
抽象的。了解气溶胶粒子的活化作用对于评估气溶胶对气候的间接影响至关重要。对气溶胶粒子活化的长期观测有助于理解AIEs，缩小AIEs模拟的不确定性。然而，它们仍然稀少。本研究利用德国中欧研究站4年多的气溶胶观测资料，对气溶胶粒子的活化过程进行了研究，并提出了改进云凝结核（CCN，NCCN）数浓度预报的建议。(1)提供了Melpitz的总体CCN活化特性。随着过饱和度（SS）从0.1%增加到0.7%，中值NCCN从399增加到2144 cm-3，其代表直径范围为10-800 nm的总颗粒数浓度的10%到48%，而吸湿系数（κ）和临界直径（Dc）分别从0.27和176 nm降至0.19和54 nm。(2)气溶胶粒子活化在不同季节变化很大，特别是在低SS条件下。在SS= 0.1%时，冬季的NCCN和活化率（AR）的中位数分别是夏季值的1.6和2.3倍。(3)κ和混合态都与尺寸有关。随着粒径（Dp）的增加，κ在Dp为40 ~ 100 nm时增加，在Dp为100 ~ 200 nm时几乎保持不变，而外部混合度在Dp为40 ~ 200 nm时不断降低。κ与Dp和混合度与Dp的关系均符合幂律函数。(4)尺寸分辨κ改进了NCCN预测。我们建议将κ-Dp幂律拟合应用于Melpitz的NCCN预测，其性能优于使用常数κ 0.3和来自粒子化学成分的κ，并且比使用NCCN（AR）与SS关系要好得多。在Melpitz测得的κ-Dp幂律拟合可用于预测其他农村地区的NCCN。为了提高对NCCN的预报水平，还需要进行长期的单分散CCN观测，以获得不同地区的κ-Dp关系及其季节变化。
Abstract. Understanding aerosol particle activation is essential for evaluating aerosol indirect effects (AIEs) on climate. Long-term measurements of aerosol particle activation help to understand the AIEs and narrow down the uncertainties of AIEs simulation. However, they are still scarce. In this study, more than 4 years of comprehensive aerosol measurements were utilized at the central European research station of Melpitz, Germany, to gain insight into the aerosol particle activation and provide recommendations on improving the prediction of number concentration of cloud condensation nuclei (CCN, NCCN). (1) The overall CCN activation characteristics at Melpitz are provided. As supersaturation (SS) increases from 0.1 % to 0.7 %, the median NCCN increases from 399 to 2144 cm−3, which represents 10 % to 48 % of the total particle number concentration with a diameter range of 10–800 nm, while the median hygroscopicity factor (κ) and critical diameter (Dc) decrease from 0.27 to 0.19 and from 176 to 54 nm, respectively. (2) Aerosol particle activation is highly variable across seasons, especially at low-SS conditions. At SS=0.1 %, the median NCCN and activation ratio (AR) in winter are 1.6 and 2.3 times higher than the summer values, respectively. (3) Both κ and the mixing state are size-dependent. As the particle diameter (Dp) increases, κ increases at Dp of ∼40 to 100 nm and almost stays constant at Dp of 100 to 200 nm, whereas the degree of the external mixture keeps decreasing at Dp of ∼40 to 200 nm. The relationships of κ vs. Dp and degree of mixing vs. Dp were both fitted well by a power-law function. (4) Size-resolved κ improves the NCCN prediction. We recommend applying the κ–Dp power-law fit for NCCN prediction at Melpitz, which performs better than using the constant κ of 0.3 and the κ derived from particle chemical compositions and much better than using the NCCN (AR) vs. SS relationships. The κ–Dp power-law fit measured at Melpitz could be applied to predict NCCN for other rural regions. For the purpose of improving the prediction of NCCN, long-term monodisperse CCN measurements are still needed to obtain the κ–Dp relationships for different regions and their seasonal variations.