大气本底站CO2观测浓度的源汇区域代表性研究

Focusing on scientific problems and national demands of low-carbon development and climate change, the representativeness of CO2 concentrations and regional source/sink characteristics will be studied at 4 atmospheric background stations. The atmospheric inversion model FLEXPART will be used to simulate and determine potential source areas impacting on observational concentrations of stations. Carbon Tracker model will also be used to inverse spatial and temporal distribution of CO2 concentrations and fluxes. Combined with the network sampling observation data, the optimal threshold of footprint function can be found with numerical iterative method and correlation analysis. The area coverage of source and sink of CO2 observation concentration at the station can be obtained. The method tracking source area will be established. Based on in-situ CO2 observation concentrations at the atmospheric background station, CO2 source/sink characteristics for background and non-background source area of station will be analyzed to explore the different influences by natural conditions and human activities. CO2 source/sink characteristics in different typical areas and their significances in the pattern of Chinese carbon source/sink will be discussed. A scientific and effective method will be given to obtain the source/sink representativeness of CO2 observation concentrations and regional characteristics through the research of this project. There are important scientific significance and application value for rational utilization of CO2 observation data to inverse global/regional CO2 flux, analyze CO2 source/sink characteristics, design and arrange CO2 observation sites.

以低碳发展、应对气候变化的科学问题和国家需求为着眼点，在4个大气本底站开展CO2观测浓度代表性和区域源汇特征研究。利用大气反转模式FLEXPART模拟影响测站观测浓度的潜在源区分布，利用Carbon Tracker模式反演CO2浓度和通量的时空分布，结合网络化采样观测CO2数据并通过数值迭代方法和相关性分析方法获取最优印痕函数阈值，得到测站CO2观测浓度所代表的源汇区域范围，建立源区追踪方法。采用大气本底站CO2在线观测资料，对本底和非本底源区的碳源汇特征进行分析，探究自然条件和人类活动对其影响的差异。综合分析不同典型区域中CO2 源汇特征以及它们在中国区域碳源汇格局中的意义。通过本项目研究将给出一种分析观测站点CO2浓度源区代表性及区域源汇特征的方法，对于合理利用CO2观测数据进行全球或区域碳通量反演和碳源汇特征分析、合理设计和布局CO2观测站点具有重要的科学意义与应用价值。

针对大气中CO2浓度时空分布与源汇特征这一热点科学问题以及低碳发展、应对气候变化和环境外交的国家需求，本项目利用大气反转模式FLEXPART模拟影响测站的潜在源区分布，利用Carbon Tracker模式反演CO2浓度和通量，结合多源CO2数据资料在我国4个WMO-GAW大气本底站开展了CO2浓度源汇区域代表性研究，通过数值迭代方法和相关性分析手段初步建立测站CO2浓度源区追踪方法，得到了测站CO2浓度所代表的源汇区域范围，获得了四个不同典型区域中CO2源汇特征。结果表明：上甸子站和龙凤山站CO2本底浓度代表区域较小，而瓦里关和临安站较大；瓦里关和上甸子站夏季CO2本底浓度代表区域比冬季大，但是临安站和龙凤山站情况相反；各站夏季和冬季的CO2本底浓度代表区域分布在四个典型区域，各区域内的CO2净通量呈现了明显的季节周期；一年中大部分月份瓦里关站是碳汇，而三个区域本底站表现为较强的碳源。这些结果有助于CO2测站代表性评价和多源数据应用，并增进我国不同地区CO2源汇特征的认识。