Production of Aerosol paRticle orgAnic Matter in ClOUds: chamber and laboratory studies, mechanisms, modelling and iNTegration

最近，云中的化学过程被认为对有机气溶胶粒子质量有很大的贡献。来自HCCT-2010实地研究和积云小室研究的最新证据表明，这种有机大量生产可能是大量的，并取决于气相中可用有机前体化合物的浓度。然而，存在着相当大的不确定性，例如，产生的气溶胶颗粒的性质可能是亚稳定的，在云滴蒸发过程中至少有一部分OM含量是松散的。因此，派拉蒙的目标是研究能够处理有机成分并产生有机气溶胶颗粒物的云过程。该项目将侧重于非常相关的多官能前体的多相化学，如多官能羰基和酸。利用这些前体，将开展水相实验室和CESAM小室研究相结合的工作，以检查多相云过程。首先，水相实验室研究将为上述化合物的多相加工的动力学和机理奠定基础。然后，建议的CESAM室内实验--在派拉蒙中心--将重点研究这些化合物在云中的化学处理过程中产生的有机物质，这些化合物逐一、分组或与所有化合物混合。计划中的室内研究将使用不同的种子和氧化剂前体，以检查在不同环境和白天条件下的有机大规模生产。我们将对云集期间的有机质量增加进行研究。除了有机物质的形成，还应研究云条件下有机化合物的分配，以评估在云场活动HCCT-2010期间观察到的有机羰基化合物可能的浓缩。有机气溶胶组分将由两台气溶胶质谱仪在线分析，间隙气相的处理和相分配将通过PTR-MS和使用小型计数器虚拟撞击器(CVI)进行研究，然后进行离线分析。最后，进行的CESAM实验是用复杂的多相化学机制MCM/CAPRAM模拟的。将进行多阶段模拟，以验证机制并支持对室内实验的解释。总体而言，拟议的派拉蒙项目将是一项科学突破，有助于理解云内过程，澄清云对大气有机气溶胶大量产生的作用。

Recently, chemical processes in clouds have been suggested to contribute substantially to organic aerosol particle mass. Recent evidence from the HCCT-2010 field study and the CUMULUS chamber study suggest that this organic mass production can be substantial and depends on the concentration of available organic precursor compounds in the gas phase. However, considerable uncertainties exist, e.g. with regards to the nature of the resulting aerosol particles which might be metastable and loose at least part of their OM content during the cloud droplet evaporation. Hence, PARAMOUNT is aimed at the investigation of cloud processes which are able to process organic constituents and produce organic aerosol particle mass. The project will focus on the multiphase chemistry of very relevant polyfunctional precursors such as polyfunctional carbonyls and acids. With these precursors, a combination of aqueous-phase laboratory and CESAM chamber studies will be undertaken to examine the multiphase cloud processing. Firstly, aqueous-phase laboratory studies will lay the groundwork with regard to kinetics and mechanisms of the multiphase processing of the mentioned compounds. Then, the suggested CESAM chamber experiments, which are central in PARAMOUNT, will focus on studying the organic mass production by the chemical in-cloud processing of these compounds one by one, grouped or with mixtures with all of them. The planned chamber studies will use different seeds and oxidant precursors to examine the organic mass production under different environmental and diurnal conditions. The organic mass increase during the cloud episodes will be investigated. Besides the organic mass formation, the partitioning of organic compounds under cloud conditions should be studied to evaluate possible enrichments of organic carbonyl compounds observed during the cloud field campaign HCCT-2010. The organic aerosol fraction will be analysed on-line by two Aerosol Mass Spectrometer instruments and the processing of the interstitial gas phase and the phase partitioning will be investigated by PTR-MS and the use of a mini CVI (counter virtual impactor) followed by off-line analysis. Finally, the performed CESAM experiments are being modelled with the complex multiphase chemistry mechanism MCM/CAPRAM. The multiphase modelling will be performed to both validate the mechanism and support the interpretation of the chamber experiments. Overall, the proposed project PARAMOUNT will be a scientific breakthrough for understanding of in-cloud processes clarifying the role of clouds for atmospheric organic aerosol mass production.