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Anthropogenic Methane Emission and Its Partitioning for the Yangtze River Delta Region of China
Author(s) -
Hu Cheng,
Griffis Timothy J.,
Liu Shoudong,
Xiao Wei,
Hu Ning,
Huang Wenjing,
Yang Dong,
Lee Xuhui
Publication year - 2019
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2018jg004850
Subject(s) - environmental science , emission inventory , delta , atmospheric sciences , atmospheric research , methane , inversion (geology) , greenhouse gas , china , flux (metallurgy) , scaling , climatology , meteorology , geography , air quality index , mathematics , geology , chemistry , physics , structural basin , paleontology , oceanography , geometry , organic chemistry , archaeology , astronomy
Urban areas are global methane (CH 4 ) hotspots. Yet large uncertainties still remain for the CH 4 budget of these domains. The Yangtze River Delta (YRD), China, is one of the world's most densely populated regions where a large number of cities are located. To estimate anthropogenic CH 4 emissions in YRD, we conducted simultaneous atmospheric CH 4 and CO 2 mixing ratio measurements from June 2010 to April 2011. By combining these measurements with the Weather Research and Forecasting and Stochastic Time‐Inverted Lagrangian Transport models and a priori Emission Database for Global Atmospheric Research emission inventories, we applied three “top‐down” approaches to constrain anthropogenic CH 4 emissions. These three approaches included multiplicative scaling factors, flux ratio, and scale factor Bayesian inversion. The posteriori CH 4 flux density estimated from the three approaches showed high consistency and were 36.32 (±9.17), 35.66 (±2.92), and 36.03(±14.25) nmol·m −2 ·s −1 , respectively, for the duration of the study period (November 2010 to April 2011). The total annual anthropogenic CH 4 emission was 6.52(±1.59) Tg for the YRD region based on the average of these three approaches. Our emission estimates were 30.2(±17.6)%, 31.5 (±5.6)%, and 30.8 (±27.4)% lower than the a priori Emission Database for Global Atmospheric Research v432 emission inventory estimate. The scale factor Bayesian inversion results indicate that the overestimate was mainly caused by two source categories including fuel exploitation and agricultural soil emissions (rice cultivation). The posteriori flux densities for agricultural soil and fuel exploitation were 10.68 and 6.34 nmol·m −2 ·s −1 , respectively, and were 47.8% and 29.2% lower than the a priori inventory. Agricultural soil was the largest source contribution and accounted for 29.6% of the YRD CH 4 budget during the study period.