Decadal Methane Emission Trend Inferred from Proxy GOSAT XCH4 Retrievals:Impacts of Transport Model Spatial Resolution  

作　　者：Sihong ZHU Liang FENG Yi LIU Jing WANG Dongxu YANG 

机构地区：[1]Carbon Neutrality Research Center,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China [2]National Centre for Earth Observation,University of Edinburgh,Edinburgh,EH93FF,UK [3]University of Edinburgh,Edinburgh,EH93FF,UK [4]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Advances in Atmospheric Sciences》2022年第8期1343-1359,共17页大气科学进展（英文版）

基　　金：supported by the National Key R&D Plan of China(Grant No.SQ2019YFE013078);the Key Research Program of the Chinese Academy of Sciences(Grant No.ZDRW-ZS-2019-1);the National Key R&D Program of China(Grant No.2017YFB0504000)。

摘　　要：In recent studies,proxy XCH_(4)retrievals from the Japanese Greenhouse gases Observing SATellite(GOSAT)have been used to constrain top-down estimation of CH_(4)emissions.Still,the resulting interannual variations often show significant discrepancies over some of the most important CH_(4)source regions,such as China and Tropical South America,by causes yet to be determined.This study compares monthly CH_(4)flux estimates from two parallel assimilations of GOSAT XCH_(4)retrievals from 2010 to 2019 based on the same Ensemble Kalman Filter(EnKF)framework but with the global chemistry transport model(GEOS-Chem v12.5)being run at two different spatial resolutions of 4°×5°(R4,lon×lat)and 2°×2.5°(R2,lon×lat)to investigate the effects of resolution-related model errors on the derived long-term global and regional CH_(4)emission trends.We found that the mean annual global methane emission for the 2010s is 573.04 Tg yr^(-1)for the inversion using the R4 model,which becomes about 4.4 Tg yr^(-1)less(568.63 Tg yr^(-1))when a finer R2 model is used,though both are well within the ensemble range of the 22 top-down results(2008-17)included in the current Global Carbon Project(from 550 Tg yr^(-1)to 594 Tg yr^(-1)).Compared to the R2 model,the inversion based on the R4 tends to overestimate tropical emissions(by 13.3 Tg yr^(-1)),which is accompanied by a general underestimation(by 8.9 Tg yr^(-1))in the extratropics.Such a dipole reflects differences in tropical-mid-latitude air exchange in relation to the model’s convective and advective schemes at different resolutions.The two inversions show a rather consistent long-term CH_(4)emission trend at the global scale and over most of the continents,suggesting that the observed rapid increase in atmospheric methane can largely be attributed to the emission growth from North Africa(1.79 Tg yr^(-2)for R4 and 1.29 Tg yr^(-2)for R2)and South America Temperate(1.08 Tg yr^(-2)for R4 and 1.21 Tg yr^(-2)for R2)during the first half of the 2010s,and from Eurasia Boreal(1.46 Tg yr^(-2)f

关 键 词：methane emissions long-term trend horizontal resolution 

分 类 号：X831[环境科学与工程—环境工程]