title: Characterization of urban CO2column abundance with a portable low resolution spectrometer (PLRS): Comparisons with GOSAT and GEOS-Chem model data.
abstract: We presented the characterization of urban CO2column abundance (XCO2) in Hefei, China using a portable low resolution spectrometer (PLRS). An optimized correction spectrum was introduced in the spectral fitting to improve CO2retrieval. A pronounced seasonal cycle and diurnal variation were observed with a precision of ~0.12%. The CO2concentrations in winter are about 5-10ppm higher than those in summer. Most diurnal variations exhibited downward trends. The measurement in the early morning is about 2-5ppm higher than the late afternoon observation. The causes of the seasonal and diurnal trends were systematic analyzed. The coincident CO2time series were compared with the Greenhouse Gases Observing SATellite (GOSAT) data and the GEOS-Chem global 3-D tropospheric chemistry model data. We found the ground based (g-b) PLRS data are systematically higher than the GOSAT and the GEOS-Chem data. Compared to the GOSAT data, the g-b PLRS data are 0.26ppm (0.07%) higher with a standard deviation of 1.70ppm (0.43%). Compared to the smoothed GEOS-Chem model data, the g-b PLRS data shows a 1.31ppm (0.33%) higher with a standard deviation of 5.30ppm (0.87%). The g-b PLRS generally reproduced the seasonal cycle observed by GOSAT and GEOS-Chem model with correlation coefficients (r) of 0.82 and 0.64, respectively.
authors.affiliation: Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
authors.forename: Youwen
authors.initials: Y
authors.lastname: Sun
authors.affiliation: School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China; Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China. Electronic address: chliu81@ustc.edu.cn.
authors.forename: Cheng
authors.initials: C
authors.lastname: Liu
authors.affiliation: Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Pinhua
authors.initials: P
authors.lastname: Xie
authors.affiliation: Meteorological Institute, Ludwig-Maximilians Universität München, Munich, Germany.
authors.forename: Kalok
authors.initials: K
authors.lastname: Chan
authors.affiliation: Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
authors.affiliation: Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Key Lab of Environmental Optics & Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Jianguo
authors.initials: J
authors.lastname: Liu
keywords: Carbon dioxide; City emission; GEOS-Chem; GOSAT; Remote sensing; Seasonal cycle