[A-CG36] 衛星による地球環境観測

[ACG36-12] Country-level estimates of sectoral anthropogenic methane emissions by inversion of GOSAT and surface observations, and their decadal trends

*rajesh janardanan¹、Shamil S Maksyutov¹、Fenjuan Wang¹、Lorna Raja Nayagam¹、Saroj Kumar Sahu²、Poonam Mangaraj²、Marielle Saunois³、Xin Lan^4,5、Tsuneo Matsunaga¹ (1.SOC,NIES, Tsukuba, Japan、2.Utkal Univ., Bhubaneswar, India、3.LSCE, Paris, France、4.CIRES, Univ. of Colorado Boulder, CO, USA、5.NOAA GML, Boulder, CO, USA)

キーワード：Anthropogenic methane emissions, inverse modeling, GOSAT, methane trend, wetland methane emissions

We used a high-resolution inverse model NIES-TM-FLEXPART-VAR (NTFVAR) to estimate sectoral methane emissions using GOSAT and surface observations for the period 2009-2020 and report the country-level emission trends for each optimized sector. Our prior emissions include anthropogenic sectors from EDGAR database, oil and gas emissions from GAINS model, biomass burning emissions from GFED, and other sources following Saunois et al (2020). The model optimizes six emission categories, such as agriculture, waste, biomass burning, coal, oil and gas, and wetlands, on a biweekly time step. The estimated global total emissions show a growth rate of 2.6 Tg yr⁻² (p <0.05) for the analysis period, with significant contributions from waste (1.1 Tg yr⁻²) and agriculture (0.09 Tg yr⁻²) sectors. Whereas the aggregated sectoral emissions at country-level showed statistically significant (p<0.1) trends in total posterior emissions for China (0.56 Tg yr⁻²), India (0.22 Tg yr⁻²), United States (0.65 Tg yr⁻²), Indonesia (0.28 Tg yr⁻²), and Pakistan (0.22 Tg yr⁻²) among the major methane emitters. Major emission sectors contributing to the country-level trends are -China (waste 0.35; oil and gas 0.07 Tg yr⁻²), India (agriculture 0.09; waste 0.11 Tg yr⁻²), United States (oil and gas 1.0; agriculture 0.07; coal -0.15 Tg yr⁻²), Russia (coal 0.11; oil and gas -0.42; biomass burning 0.15 Tg yr⁻²), Indonesia (coal 0.28 Tg yr⁻²), and Pakistan (agriculture 0.15 Tg yr⁻²; waste 0.03 Tg yr⁻²). In the case of wetland methane emissions, Russia (0.24 Tg yr⁻²) and central African countries such as Congo (0.12 Tg yr⁻²); Democratic Republic of Congo (0.24 Tg yr⁻²); Sudan (0.03 Tg yr⁻²), etc. have a positive trend, considerably large after 2017, whereas Bolivia (-0.1 Tg yr⁻²) Brazil (-0.11 Tg yr⁻²) and Argentina (-0.08 Tg yr⁻²) have a declining trend. Our results indicate the key emission sectors to be targeted on national level for efficient methane emission mitigation efforts.

Reference
Saunois, M., et al.: The Global Methane Budget 2000–2017, Earth Syst. Sci. Data, 12, 1561–1623, https://doi.org/10.5194/essd-12-1561-2020, 2020.