北京上甸子大气本底站CO2浓度的源汇区域代表性研究

为研究单个站点观测浓度的源汇区域代表性及所在区域的CO2通量特征,利用大气反转模式FLEXPART模拟确定影响上甸子站观测浓度的气团主要来源,利用Carbon Tracker模式反演CO2浓度和通量的时空分布,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,得到影响测站CO2浓度的源汇区域范围.其次,将在线观测CO2浓度筛分为本底和非本底浓度,利用FLEXPART模式追踪测站本底和非本底源区,研究发现,本底和非本底源汇区域明显不同并随季节变化.在印痕函数大于一定阈值的潜在源区内,本底和非本底区域净通量变化趋势差异明显,而且在各通量分支中本底区域化石燃料通量较小、生物圈通量较大,非本底区域化石燃料通量较大、生物圈通量较小.通过反演模式能够定量得到影响测站观测浓度的源汇区域及区域通量特征.

CO2 concentration representation of source and sink area at Shangdianzi atmospheric background station in Beijing

In order to study the spatial representativeness of CO2 source and sink about observing concentrations at a single station and the regional flux characteristics, the atmospheric inversion model FLEXPART was used to simulate and determine the main source of air mass impacting on observed concentration at ShangDianZi station. Carbon Tracker model was also used to inverse spatial and temporal distributionof CO2 concentrations and fluxes. The optimal threshold of footprint function was found with numerical iterative approach and correlation analysis, and then the distribution of source and sink area of CO2 observation concentration at the station was obtained. Then, the in-situ CO2 observation concentrations were screened into two parts, the background and the non-background, for tracking the background and non-background source area of station with FLEXPART model. The results showed that the background and non-background source regions were obviously different and changed with the seasons. In the potential source area where footprint function was greater than the threshold, the background and non-background regional net fluxes changed differently. The fossil fuel flux was smaller and the biosphere flux was larger in the background area. However, it was opposite for the non-background area. Therefore, source and sink area, influencing the concentrations of observing station, and regional characteristics of fluxes could be quantified using inversion models.