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，对流层低层和中层的大部分都存在着大量的次生有机气溶胶(SOA)。因此，对这一重要气溶胶成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。大多数最新的模型系统性地低估了大气中存在的SOA的质量，这可能是因为对其生产的经验参数不正确。为了在这个问题上取得进展，迫切需要专门针对进程的研究。鉴于其对气候问题的重要性，保存在阿尔卑斯山冰芯档案中的SOA的长期趋势需要深入探讨。在这种背景下，该建议的目的是(1)了解成核/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)量化阿尔卑斯山冰芯的长期趋势，从而推断其控制原因。建议的方法结合了三个山区的密集大气场运动(物理和化学气溶胶性质，可能是SOA的前体)，以及输送化学模拟和阿尔卑斯山冰芯调查。气溶胶物理测量与大气-化学/气溶胶模式的模拟相结合，以量化整个对流层成核/凝结的作用，迄今从未在大气观测和模拟的综合研究中涉及。从高山冰芯推断的、由放射性碳限制支持的持续长期的SOA趋势将首次被记录在案。这种尝试还包括被怀疑是众多SOA贡献者的主要贡献者之一的HULIS。

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.