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

在大气中排放的挥发性有机化合物在复杂的反应序列中被氧化。这种逐步氧化导致中间体物种的形成，这些中间物种的极性增加，蒸气压降低。这种有机化合物容易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确实发挥了重要作用。由于缺乏关于高度功能化物种的详细组成的信息，这些次生有机物对环境影响的程度仍然难以量化。为了探索有机碳在大气氧化过程中的演化，制定完全明确的化学方案似乎是必要的。然而，描述多相氧化的完全明确的模型将涉及大量的中间物种。这一事实排除了手动描述众多物理和化学变化的任何尝试。此外，开发显式模型所需的物理和化学数据量远远超过现有的实验数据。LISA和NCAR(科罗拉多州博尔德)已经开始开发一种数据处理工具，该工具允许基于自动生成方法开发完全显式的气相氧化方案。本项目的目标是(I)根据现有的和最新的IFT水相动力学数据，包括目前最详细的水相化学机理CAPRAM和各种估计方法，将该专家系统扩展到生成显式的水相氧化方案；(Ii)使用0-D箱模型探索云系统中有机物的演化；(Iii)通过对氧化机理关键物种的室内研究来验证模型结果，最后(Iv)机理还原。这种机制开发、应用、室内实验验证和还原的组合将增强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，用于开发简化的机制，用于更高规模的建模等应用。

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.