Spatiotemporal Variations of Atmospheric Methane over the Korean Peninsula from Sentinel-5P/TROPOMI Observations

This study investigates spatiotemporal variations in column-average dry-air mole fractions of methane (XCH4) over the Korean Peninsula from 2019 to 2024 using TROPOspheric Monitoring Instrument (TROPOMI) satellite observations.To assess data accuracy, satellite retrievals were compared with ground-based Total Carbon Column Observing Network (TCCON) measurements at Anmyeondo, Korea, and Saga, Japan.Despite limited data availability at Anmyeondo (N = 7) due to harsh coastal conditions, the validation showed a high correlation (R > 0.88) and consistent seasonal variations at both sites, confirming the accuracy of TROPOMI retrievals.The results revealed a distinct "west-high, eastlow" spatial pattern of XCH4 over the Korean Peninsula.This distribution reflects the concentration of major anthropogenic sources in western regions, including the densely populated Seoul Metropolitan Area, large-scale industrial complexes, and coal-fired power plants, showing strong qualitative and quantitative agreement with the Emissions Database for Global Atmospheric Research (EDGAR) 2025 emission inventory.In general, the mean XCH4 concentration increased continuously across the Korean Peninsula, except for a temporary stagnation in 2022.Notably, a synchronized rapid surge was observed across all major regions in 2024, peaking at 1912.58 ppb.Regional analysis indicated that, while local industrial emissions (e.g., in Gyeongnam) drove regional heterogeneity until 2023, the sharp increase in 2024 was likely driven by strong external factors, such as the global rise in background methane levels or large-scale meteorological influences.These findings provide important insights into regional variations in methane levels and emissions across the Korean Peninsula.These results demonstrate that TROPOMI not only effectively captures anthropogenic emission patterns aligned with EDGAR but also identifies potential natural sources unique to the Korean Peninsula's environmental characteristics.By bridging the gap between existing emission inventories and real-world observations, our findings highlight the critical role of satellite-based monitoring in establishing comprehensive, data-driven strategies for regional methane management and achieving national climate goals.