Characterization of Regional Combustion Efficiency using ΔXCO: ΔXCO2 Observed by a Portable Fourier-Transform Spectrometer at an Urban Site in Beijing

Ke Che; Yi Liu; Zhaonan Cai; Dongxu Yang; Haibo Wang; Denghui Ji; Yang Yang; Pucai Wang

doi:10.1007/s00376-022-1247-7

Characterization of Regional Combustion Efficiency using ΔXCO: ΔXCO₂ Observed by a Portable Fourier-Transform Spectrometer at an Urban Site in Beijing

Adv Atmos Sci. 2022;39(8):1299-1315. doi: 10.1007/s00376-022-1247-7. Epub 2022 May 11.

Authors

Ke Che^{1

2

3}, Yi Liu^{2

3}, Zhaonan Cai², Dongxu Yang², Haibo Wang^{1

3}, Denghui Ji^{1

3}, Yang Yang^{1

3}, Pucai Wang^{2

3}

Affiliations

¹ Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Science, Beijing, 100029 China.
² Carbon Neutrality Research Center, Institute of Atmospheric Physics, Chinese Academy of Science, Beijing, 100029 China.
³ University of Chinese Academy of Science, Beijing, 100049 China.

Abstract
in English, Chinese

Measurements of column-averaged dry-air mole fractions of carbon dioxide and carbon monoxide, CO₂ (XCO₂) and CO (XCO), were performed throughout 2019 at an urban site in Beijing using a compact Fourier Transform Spectrometer (FTS) EM27/SUN. This data set is used to assess the characteristics of combustion-related CO₂ emissions of urban Beijing by analyzing the correlated daily anomalies of XCO and XCO₂ (e.g., ΔXCO and ΔXCO₂). The EM27/SUN measurements were calibrated to a 125HR-FTS at the Xianghe station by an extra EM27/SUN instrument transferred between two sites. The ratio of ΔXCO over ΔXCO₂ (ΔXCO:ΔXCO₂) is used to estimate the combustion efficiency in the Beijing region. A high correlation coefficient (0.86) between ΔXCO and ΔXCO₂ is observed. The CO:CO₂ emission ratio estimated from inventories is higher than the observed ΔXCO:ΔXCO₂ (10.46 ± 0.11 ppb ppm^-1) by 42.54%-101.15%, indicating an underestimation in combustion efficiency in the inventories. Daily ΔXCO:ΔXCO₂ are influenced by transportation governed by weather conditions, except for days in summer when the correlation is low due to the terrestrial biotic activity. By convolving the column footprint [ppm (µmol m^-2 s^-1)^-1] generated by the Weather Research and Forecasting-X-Stochastic Time-Inverted Lagrangian Transport models (WRF-X-STILT) with two fossil-fuel emission inventories (the Multi-resolution Emission Inventory for China (MEIC) and the Peking University (PKU) inventory), the observed enhancements of CO₂ and CO were used to evaluate the regional emissions. The CO₂ emissions appear to be underestimated by 11% and 49% for the MEIC and PKU inventories, respectively, while CO emissions were overestimated by MEIC (30%) and PKU (35%) in the Beijing area.

城市作为主要碳源,在全球碳循环中起重要作用。本文利用小型傅里叶光谱仪 EM27/SUN FTS在北京城区开展连续高精度大气温室气体CO₂及人为排放示踪污染气体CO的大气柱平均干空气混合比 (XCO₂, XCO)观测。为获取EM27/SUN绝对精度,实验前后已与TCCON香河站的高分辨率光谱仪125HR-FTS交叉对比。 XCO和XCO₂的日变化异常(ΔXCO, ΔXCO₂) 高度相关 (R2=0.86),通过研究ΔXCO与ΔXCO₂的比例关系 (ΔXCO:ΔXCO₂) 有助于解析北京城区人为碳排放相关的燃烧效率。除去夏季受生态吸收影响的数据后,2019年北京城区ΔXCO:ΔXCO₂ (10.46 ± 0.11 ppb ppm−1) , 明显高于同期北半球城区TCCON FTS站点观测比例值。逐日ΔXCO:ΔXCO₂ 易受周围气象场传输影响,通过WRF-XSTILT 大气传输模型对不同来源聚类分析可知,来自南部污染区的ΔXCO:ΔXCO₂明显低于西北干净源。利用WRF-XSTILT和两种“自下而上”碳排放清单 (MEIC, PKU) 估计的CO:CO₂比观测结果高42.54%-101.15%,表明清单对北京城区燃烧效率的低估。进一步将粗网格分辨率模型CAMS作为大背景,北京地区MEIC和PKU的分别约低估了11 % 和49 %的人为CO₂排放量,而CO排放量被高估30 %和35%。.

Keywords: FTS; combustion efficiency; megacity; remote sensing; ΔXCO:ΔXCO2.

Abstract in English, Chinese

Abstract
in English, Chinese