Preprints
https://doi.org/10.5194/acp-2021-13
https://doi.org/10.5194/acp-2021-13

  22 Mar 2021

22 Mar 2021

Review status: a revised version of this preprint was accepted for the journal ACP and is expected to appear here in due course.

Reduction in C2H6  from 2015 to 2020 over Hefei, eastern China  points to air quality improvement in China

Youwen Sun1, Hao Yin1,3, Cheng Liu1,2,4,5, Emmanuel Mahieu6, Justus Notholt7, Yao Té8, Xiao Lu9, Mathias Palm7, Wei Wang1, Changong Shan1, Qihou Hu1, Min Qin1, Yuan Tian10, and Bo Zheng11 Youwen Sun et al.
  • 1Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
  • 2Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
  • 3University of Science and Technology of China, Hefei, 230026, China
  • 4Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230026, China
  • 5Anhui Province Key Laboratory of Polar Environment and Global Change, USTC, Hefei, 230026, China
  • 6Institute of Astrophysics and Geophysics, University of Liège, Belgium
  • 7University of Bremen, Institute of Environmental Physics, P. O. Box 330440, 28334 Bremen, Germany
  • 8Laboratoire d'Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères (LERMA-IPSL), Sorbonne Université, CNRS, Observatoire de Paris, PSL Université, 75005 Paris, France
  • 9School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
  • 10Anhui University Institutes of Physical Science and Information Technology, Hefei 230601, China
  • 11Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China

Abstract. Ethane (C2H6) is an important greenhouse (GHG) gas and plays a significant role in tropospheric chemistry and climate change. This study first presents and quantifies the variability, source, and transport of C2H6 over densely populated and industrialized eastern China by using ground-based high-resolution Fourier transform infrared (FTIR) remote sensing technique. We obtained a retrieval error of 6.21 ± 1.2 (1σ) % and degrees of freedom (DOFS) of 1.47 ± 0.2 (1σ) in retrieval of C2H6 tropospheric column-averaged dry-air mole fraction (troDMF) over Hefei, eastern China (117°E, 32°N, 30 m a.s.l.). The observed C2H6 troDMF reached a minimum monthly mean value of (0.36 ± 0.26) ppbv in July and a maximum monthly mean value of (1.76 ± 0.35) ppbv in December, and showed a negative change rate of (−2.60 ± 1.34) %/yr from 2015 to 2020. The dependencies of C2H6 troDMF on meteorological and emission factors were analyzed by using generalized additive models (GAMs). Generally, both meteorological and emission factors have positive influences on C2H6 troDMF in cold season (DJF/MAM) and negative influences on C2H6 troDMF in warm season (JJA/SON). GEOS-Chem chemical model simulation captured the observed C2H6 troDMF variability and was thus used for source attribution. GEOS-Chem model sensitivity simulations concluded that the anthropogenic emissions (fossil fuel plus biofuel emissions) and the natural emissions (biomass burning plus biogenic emissions) accounted for 49.2 % and 37.1 % of C2H6 troDMF abundance over Hefei, respectively. The observed C2H6 troDMF abundance mainly results from the emissions within China (74.1 %), where central, eastern, and northern China dominated the contribution (57.6 %). Seasonal variability in C2H6 transport inflow and outflow over the observation site is largely related to the mid-latitude westerlies and Asian monsoon system. Reduction in C2H6 abundance from 2015 to 2020 mainly results from the decrease in local and transported C2H6 emissions, which points to air quality improvement in China in recent years.

Youwen Sun et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-13', Anonymous Referee #3, 19 Apr 2021
    • AC1: 'Reply on RC1', Youwen Sun, 01 Jun 2021
  • RC2: 'Comment on acp-2021-13', Anonymous Referee #2, 17 May 2021
    • AC2: 'Reply on RC2', Youwen Sun, 01 Jun 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-13', Anonymous Referee #3, 19 Apr 2021
    • AC1: 'Reply on RC1', Youwen Sun, 01 Jun 2021
  • RC2: 'Comment on acp-2021-13', Anonymous Referee #2, 17 May 2021
    • AC2: 'Reply on RC2', Youwen Sun, 01 Jun 2021

Youwen Sun et al.

Youwen Sun et al.

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Short summary
Variability, source and transport of Ethane (C2H6) from 2015 to 2020 over eastern China using ground-based FTIR spectroscopy and GEOS-Chem simulation were presented. C2H6 variability are driven by both meteorological and emission factors. Reduction in C2H6 in recent years over eastern China point to air quality improvement in China.
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