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研究论文

Estimation of methane emissions in Beijing area using backward trajectory inversion model

摘要：利用连续监测的大气甲烷浓度数据和拉格朗日逆向轨迹反演模式估算出北京甲烷源排放强度,并与根据最新调查数据建立的北京地区甲烷源排放清单进行了比较.排放清单结果表明,北京地区甲烷排放总量为 296.4Gg/a,其中,最主要的甲烷排放源为城市垃圾和化石燃料,反映了北京作为一特大城市甲烷排放以人为源为主的特点.利用 2 0 0 0年 6月至 1 2月连续观测的有混合层代表性的北京大气甲烷浓度,通过奇异值分解法 (SingularValueDecomposition,SVD)反演出模拟区域的甲烷排放源强度和分布.模式计算与排放清单在甲烷源定性分布上对应较好,定量结果也是合理的.但由于可输入的气象数据有限,轨迹在整个模拟区域内覆盖不均匀,反演出的源块位置有偏差,其中偏差最大的为煤矿的甲烷排放.

Abstract：Methane emission estimates in Beijing area are derived from concentrations of atmospheric methane measured at one sampling site using a backward trajectory inversion model, and are compared with the current methane emission inventory of Beijing established by newly obtained emission factors and intensive survey of statistical data of sources. Methane emission inventory were calculated to be 296 4Gg/a,while municipal solid waste and fossil fuel account for 54 5% and 32 4% of total. This shows that Beijing is a typical metropolis with anthropogenic sources dominating methane emissions. The inversion model describes the diffusion processes in atmospheric boundary layers. The singular value decomposition (SVD) matrix inversion technique is used to calculate the methane emission strength of each grid in the simulated domain using concentrations from July to December²000. The source distribution and quantitative results from model agree relatively well with the emission inventory. As an independent approach from source inventory, the inversion model can be used as a tool to validate current methane emission inventory in regional scale. The largest uncertainty of this work is the distribution of methane emission from coal mining due to the limitation of meteorological data.

Key words：greenhouse gas emission inventory inversion model singular value decomposition (SVD)