ATMOCHEM - Modelling the multiphase evolution of organic carbon in the troposphere: Development of an expert system based on a self generating approach

排放到大气中的挥发性有机化合物在复杂的反应序列中被氧化。这种渐进的氧化导致形成具有增加的极性和降低的蒸气压的中间物种。这类有机化合物易于转移到气溶胶粒子和云滴的凝聚相中，因此在对流层多相化学中发挥重要作用。这些次生有机物的环境影响的程度仍然很难量化，由于缺乏有关的详细组成的高度功能化的物种的信息。完全明确的化学方案的发展似乎有必要探索有机碳在其大气氧化过程中的演变。然而，完全明确的模型描述多相氧化将涉及大量的中间物种。这一事实排除了任何手动描述众多物理和化学变化的尝试。此外，开发显式模型所需的物理和化学数据的数量远远超过可用的实验数据。丽莎和NCAR（Boulder，科罗拉多）已经开始开发数据处理工具，该工具允许基于自生成方法开发完全明确的气相氧化方案。本项目的目标是（i）基于现有的和最近的IfT水相动力学数据（包括目前最详细的水相化学机制CAPRAM和各种估计方法），将该专家系统扩展到在水相中生成明确的氧化方案，（ii）使用0-D箱模型探索多云系统中有机物的演变，（iii）通过对氧化机制的关键物种进行室研究来验证模型结果，最后（iv）机制还原。这种机制的开发，应用，验证室实验和还原的结合将提高目前的多相化学知识，并为科学界提供一个复杂的参考机制，为应用程序，如更高的规模建模简化机制的发展。

Volatile organic compounds emitted in the atmosphere are oxidized in complex reaction sequences. This progressive oxidation leads to the formation of intermediate species with increasing polarity and decreasing vapour pressure. Such organic compounds are subject to transfer into the condensed phases of aerosol particles and cloud droplets and do hence play an important role in tropospheric multiphase chemistry. The magnitude of the environmental effects of those secondary organics remains poorly quantified due to a lack of information concerning the detailed composition of the highly functionalised species. The development of fully explicit chemical schemes appears necessary to explore the evolution of organic carbon during its atmospheric oxidation. However, fully explicit models describing multiphase oxidation will involve a huge number of intermediate species. This fact precludes any attempt to describe the numerous physical and chemical transformations manually. Furthermore, the quantity of physical and chemical data needed to develop explicit models far exceeds available experimental data. LISA and NCAR (Boulder, Colorado) have initiated the development of a data processing tool that allows the development of fully explicit gas phase oxidation schemes based on a self generating approach. The goals of the present project are (i) to extend this expert system to the generation of explicit oxidation schemes in the aqueous phase based on available and recent IfT aqueous phase kinetic data including the currently most detailed aqueous phase chemistry mechanism CAPRAM and a variety of estimation methods, (ii) to explore the evolution of organics in cloudy systems using 0-D box models, (iii) to validate the model results by means of chamber studies for key species of the oxidation mechanism and, finally (iv) mechanism reduction. This combination of mechanism development, application, validation with chamber experiments and reduction will enhance the current multiphase chemistry knowledge and provide the scientific community a complex reference mechanism for the development of simplified mechanisms for applications such as higher scale modelling.