Preprints
https://doi.org/10.5194/acp-2021-464
https://doi.org/10.5194/acp-2021-464

  19 Aug 2021

19 Aug 2021

Review status: this preprint is currently under review for the journal ACP.

An integrated analysis of contemporary methane emissions and concentration trends over China using in situ, satellite observations, and model simulations

Haiyue Tan1, Lin Zhang1, Xiao Lu2, Yuanhong Zhao3, Bo Yao4, Robert J. Parker5,6, and Hartmut Boech5,6 Haiyue Tan et al.
  • 1Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
  • 2School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, China
  • 3College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao, China
  • 4Meteorological Observation Centre of China Meteorological Administration (MOC/CMA), Beijing, China
  • 5National Centre for Earth Observation, University of Leicester, Leicester, UK
  • 6Earth Observation Science, School of Physics and Astronomy, University of Leicester, UK

Abstract. China, being one of the major emitters of greenhouse gases, has taken strong actions to tackle climate change, e.g., to achieve carbon neutrality by 2060. It also becomes important to better understand the changes in the atmospheric mixing ratio and emissions of CH4, the second most important human-influenced greenhouse gas, in China. Here we analyze the sources contributing to the atmospheric CH4 mixing ratio and their trends in China over 2007–2018 using the GEOS-Chem model simulations driven by two commonly used global anthropogenic emission inventories: the Emissions Database for Global Atmospheric Research (EDGAR v4.3.2) and the Community Emissions Data System (CEDS). The model results are interpreted with an ensemble of surface, aircraft, and satellite observations of CH4 mixing ratios over China and the Pacific region. The EDGAR and CEDS estimates show considerable differences reflecting large uncertainties in estimates of Chinese CH4 emissions. Chinese CH4 emission estimates based on EDGAR and natural sources increase from 46.7 Tg per annum (Tg a−1) in 1980 to 69.8 Tg a−1 in 2012 with an increase rate of 0.7 Tg a−2, and estimates with CEDS increase from 32.9 Tg a−1 in 1980 and 76.7 Tg a−1 in 2014 (a much stronger trend of 1.3 Tg a−2 over the period). Both surface, aircraft, and satellite measurements indicate CH4 increase rates of 7.0–8.4 ppbv a−1 over China in the recent decade. We find that the model simulation using the CEDS inventory and interannually varying OH levels can best reproduce these observed CH4 mixing ratios and trends over China. Model results over China are sensitive to the global OH level, with a 10 % increase in the global tropospheric volume-weighted mean OH concentration presenting a similar effect to that of a 47 Tg a−1 decrease in global CH4 emissions. We further apply a tagged tracer simulation to quantify the source contributions from different emission sectors and regions. We find that domestic CH4 emissions account for 11.4 % of the mean surface mixing ratio and drive 68.3 % of the surface trend (mainly via the energy sector) in China over 2007–2018. We emphasize that intensive CH4 measurements covering eastern China will help better assess the driving factors of CH4 mixing ratios and support the emission mitigation in China.

Haiyue Tan et al.

Status: open (until 30 Sep 2021)

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  • RC1: 'Comment on acp-2021-464', Anonymous Referee #1, 20 Aug 2021 reply

Haiyue Tan et al.

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Short summary
Methane is the second most important anthropogenic greenhouse gas. Understand methane emissions and concentration growth over China in the recent decade is important to support its mitigation. This study analyzes the contributions of methane emissions from different regions and sources over the globe to methane changes over China in 2007–2018. Our results show strong international transport influences, and emphasize the need of intensive methane measurements covering eastern China.
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