The direct and indirect radiative effects of biogenic secondary organic aerosol
The direct and indirect radiative effects of biogenic secondary organic aerosol
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DOI：
10.5194/acp-14-447-2014
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发表时间：
2013-06
影响因子：
6.3
通讯作者：
C. Scott;A. Rap;D. Spracklen;P. Forster;K. Carslaw;G. Mann;K. Pringle;N. Kivekäs;M. Kulmala-
中科院分区：
文献类型：
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作者：
C. Scott;A. Rap;D. Spracklen;P. Forster;K. Carslaw;G. Mann;K. Pringle;N. Kivekäs;M. Kulmala-
抽象的。我们使用一个全球气溶胶微物理模型与离线辐射传输模型相结合，以量化的生物次生有机气溶胶（SOA）在当今大气中的辐射效应。通过其在颗粒生长和老化中的作用，生物SOA的存在使云凝结核（CCN;在0.2%过饱和度下）的全球年平均浓度增加了3.6- 21.1%，这取决于生物挥发性有机化合物（BVOCs）的SOA生产的产量，以及同时发生的初级碳排放的性质和处理。云凝结核的增加导致全球年平均云滴数浓度（CDNC）增加1.9- 5.2%，全球平均第一气溶胶间接效应（AIE）在+0.01 W m−2和-0.12 W m−2之间。当生物氧化产物也有助于新粒子形成的早期阶段时，生物SOA的辐射影响要大得多;使用两种有机介导的新粒子形成机制，我们模拟了全球年平均第一次AIEs为−0.22 W m−2和−0.77 W m−2。生物SOA的列入大大提高了模拟的季节性循环中观察到的三个森林站点的CCN大小的颗粒浓度。当应用有机介导的成核机制时，发现了最好的相关性，这表明生物SOA的第一个AIE可能高达-0.77 W m-2。SOA的辐射影响对人为排放的存在很敏感。较低的背景气溶胶浓度模拟与人为排放从1750年引起更大的分数CCN增加和更实质性的第一AIE从生物SOA。因此，1750年到现在的人为间接辐射强迫对有关生物SOA的数量和作用的假设很敏感。我们还计算了目前全球年平均直接辐射效应在-0.08 W m−2和-0.78 W m−2之间，BVOCs氧化产生的SOA量的不确定性占了这个范围的大部分。
Abstract. We use a global aerosol microphysics model in combination with an offline radiative transfer model to quantify the radiative effect of biogenic secondary organic aerosol (SOA) in the present-day atmosphere. Through its role in particle growth and ageing, the presence of biogenic SOA increases the global annual mean concentration of cloud condensation nuclei (CCN; at 0.2% supersaturation) by 3.6–21.1%, depending upon the yield of SOA production from biogenic volatile organic compounds (BVOCs), and the nature and treatment of concurrent primary carbonaceous emissions. This increase in CCN causes a rise in global annual mean cloud droplet number concentration (CDNC) of 1.9–5.2%, and a global mean first aerosol indirect effect (AIE) of between +0.01 W m−2 and −0.12 W m−2. The radiative impact of biogenic SOA is far greater when biogenic oxidation products also contribute to the very early stages of new particle formation; using two organically mediated mechanisms for new particle formation, we simulate global annual mean first AIEs of −0.22 W m−2 and −0.77 W m−2. The inclusion of biogenic SOA substantially improves the simulated seasonal cycle in the concentration of CCN-sized particles observed at three forested sites. The best correlation is found when the organically mediated nucleation mechanisms are applied, suggesting that the first AIE of biogenic SOA could be as large as −0.77 W m−2. The radiative impact of SOA is sensitive to the presence of anthropogenic emissions. Lower background aerosol concentrations simulated with anthropogenic emissions from 1750 give rise to a greater fractional CCN increase and a more substantial first AIE from biogenic SOA. Consequently, the anthropogenic indirect radiative forcing between 1750 and the present day is sensitive to assumptions about the amount and role of biogenic SOA. We also calculate an annual global mean direct radiative effect of between −0.08 W m−2 and −0.78 W m−2 in the present day, with uncertainty in the amount of SOA produced from the oxidation of BVOCs accounting for most of this range.