ATMOCHEM - Secondary organic aerosol production in the lower free troposphere over western Europe

最近的研究表明，无论是现在还是过去，在对流层中下层的大部分地区都存在大量的二次有机气溶胶（SOA）。因此，对这一重要气溶胶组分的基本了解对于评估气溶胶（有机和无机）对过去和未来气候变化的净影响至关重要。最近的大多数模型系统地低估了当前环境中的SOA的数量，这可能是由于对其生产的不正确的经验参数化造成的。为了在这个问题上取得进展，迫切需要专门研究过程。鉴于其对气候问题的重要性，高寒冰芯档案中所保存的SOA的长期趋势需要深入探讨。在此背景下，该提案旨在(1)了解文献仍然稀缺的成核/凝结过程，(2)评估这些过程相对于对流层内不同高度存在的SOA总质量的相对重要性，(3)量化高山冰芯SOA的长期趋势，从而推断其控制原因。该方案结合了三个山区密集的大气现场活动（物理和化学气溶胶特性，可能是SOA的前体），以及运输化学模拟和高山冰芯调查。气溶胶物理测量与大气化学/气溶胶模式模拟的耦合，以量化整个对流层成核/凝结的作用，迄今为止还没有在大气观测和模式之间的联合研究中得到解决。从高山冰芯推断出的SOA的连续长期趋势，并得到放射性碳约束的支持，将首次被记录下来。这一尝试还包括HULIS，他被怀疑是SOA贡献者群体的主要贡献者之一。

Recent studies suggest a significant large abundance of secondary organic aerosol (SOA) present in a large part of the low and middle troposphere, both, for present-day as well as over the past. A basic understanding of this important aerosol fraction is therefore crucial to evaluate the net impact of aerosol (organic and inorganic) on past and future climate change. Most of very recent models systematically underestimate the mass of SOA present in the atmosphere, likely due to incorrect empirical parameterizations of its production. To progress on this question, studies dedicated to processes are urgently needed. Given its importance for climate issues, the long term trend of SOA preserved in the Alpine ice core archive needs to be profoundly explored. In this context, the proposal aims at (1) to understand nucleation/condensation processes for which documentation remains scarce, (2) to evaluate the relative importance of these processes with respect to the total mass of SOA present at different altitudes within the troposphere, (3) to quantify the long term trend of SOA from Alpine ice cores thereby inferring its controlling cause.The proposal approach combines intensive atmospheric field campaigns (physical and chemical aerosols properties, likely precursors of SOA) at three mountain sites, along with transport-chemistry simulations and Alpine ice cores investigations. The coupling of the aerosol physical measurements with the simulations from a atmosphere-chemistry/aerosol model to quantify the role of nucleation/condensation throughout the troposphere has never been addressed so far in a combined study between atmospheric observations and modelling. A continuous long term trend of SOA inferred from alpine ice core and backed up by radiocarbon constraints will be documented for the first time. This attempt includes also HULIS suspected to be one of the major contributor to the mass of SOA contributor.