我国棕色碳时空分布及其辐射强迫的综合模型评估

Atmospheric brown carbon (BrC) is not only an important pollutant driving global warming, but also changes the atmospheric oxidation capacity through its influence on photochemical reactions. Recent research has shown that the atmospheric concentrations as well as the absorption efficiency of brown carbon in China are much higher than the other countries all over the world. Therefore, it is necessary and urgent to investigate the distribution of brown carbon and its radiative effect in China. The evaluation of radiative forcing of BrC in China is currently mainly based on foreign research, which does not account for the special emission sources and optical properties of BrC in China. To fulfill this knowledge gap, we plan to use GEOS-Chem (a chemical transport model) with improved emission inventory and model parameterization for optical properties of BrC to simulate the spatial-temporal distribution of brown carbon and its absorptive properties in China. The study will account for the contribution of China’s special energy structure (residential coal combustion, field burning of crop straw, biofuel combustion, vehicle exhaust and so on) to the total BrC emissions, and the influence of different fuel types and combustion conditions, as well as the aging process on the optical properties of BrC. Combined with the AERONET and OMI retrieved data, we will reproduce the spatial-temporal distribution of BrC in China and assess its implied radiative forcing effect.

大气棕色碳(BrC)不仅是加剧全球变暖的重要污染物，还能通过影响光化学反应进而改变大气氧化能力。近期研究表明我国大气BrC浓度水平和吸光增温效率远高于世界其他国家，因此迫切需要对我国BrC分布及其辐射强迫进行综合评估。当前我国BrC辐射强迫估算主要来自国外的相关报导。但是这些研究没有考虑我国特殊的源排放类型和BrC光学性质。针对这一缺失环节，本研究拟采用GEOS-Chem化学传输模式，通过优化模式中BrC源排放及光学性质参数化方案，更好地模拟我国BrC时空分布及其吸光性质。本研究将综合考虑我国特殊能源结构（民用燃煤、秸秆焚烧、生物质燃料燃烧、机动车尾气排放等）对BrC排放量的贡献，探索不同燃料、其燃烧方式、以及气团老化过程对大气BrC光学特性的影响，并结合AERONET和OMI卫星遥感数据，对我国BrC时空分布及其辐射强迫进行综合评估。

大气棕色碳(BrC)不仅是加剧全球变暖的重要污染物，还能通过影响光化学反应进而改变大气氧化能力。当前我国BrC辐射强迫估算主要来自国外的相关报导。但是这些研究没有考虑我国特殊的源排放类型和BrC光学性质。针对这一缺失环节，本研究通过综合考虑我国特殊能源结构，建立了BrC本地源清单及其吸光性的参数化方案，同时结合GEOS-Chem化学传输模式，揭示了我国BrC时空分布及其吸光贡献。.首先在本地BrC源清单方面，本项目基于文献调研，统计分析了现有研究报导的不同污染源的BrC排放因子、BrC与有机碳（OC）或黑碳（BC）的相对比例等数据，针对我国生物质燃烧、居民燃煤和机动车尾气这三大类主要BrC排放源对我国BrC排放进行了全面系统的估算。在此基础上，进一步考虑污染源类别及燃烧条件建立了BrC光学性质参数化方案，同时结合BrC源排放清单，进一步给出BrC的吸光性排放清单。.结合BrC排放清单和吸光性排放清单，本项目成功在GEOS-Chem添加了BrC模拟模块，可以追踪不同来源BrC的排放、大气传输、污染分布及其吸光贡献。通过添加BrC的吸光性，显著提高了模式对气溶胶吸光性的模拟精度。在此基础上，估算了我国BrC的污染水平及其吸光贡献。