North-south inhomogeneous variations of methane emissions observed by TROPOMI over China

Accurate quantification of methane emissions is critical for global climate change mitigation, particularly given methane's high short-term warming potential. Here, we apply a divergence-driven method to TROPOMI satellite observations to derive high-resolution (0.25°× 0.25°) methane emission maps over China in 2019, independent of prior emission inventories. Our top-down estimate of China's total methane emissions in 2019 is 56.05 ± 14.01 Tg/a, consistent with the range of 40-70 Tg/a reported in previous studies. The emission distribution exhibits striking north-south asymmetry: northern regions (e.g., Xinjiang, Inner Mongolia) show higher emission intensities, dominated by energy-related sources, while southern regions have lower but more variable emissions linked to agricultural sources. Large emitters (emissions >5kg⋅km^-2⋅h^-1), though accounting for only 10% of total sources, contribute over 40% of national emissions, highlighting their disproportionate role in climate forcing. Emission fingerprints correlate with population density, indicating that anthropogenic activities drive stable, high-intensity emissions. These findings provide a framework for targeted mitigation strategies, emphasizing the need for region-specific policies to address China's diverse methane sources-insights that extend to global efforts to constrain methane's role in near-term warming.