Measurement report: Multi-platform greenhouse gas monitoring of a major petrochemical industrial complex in South Korea

Abstract. Quantifying greenhouse gas (GHG) emissions from large industrial complexes remains challenging due to the coexistence of diverse source types, highly variable operational conditions, fugitive releases, and limited representativeness of bottom-up inventories. These complexities require observational approaches resolving emissions across multiple spatial and temporal scales. To address this gap, this study conducted a coordinated multi-platform observation campaign from 6–14 January 2024 at the Daesan Petrochemical Industrial Complex (DPIC), one of South Korea’s largest petrochemical hubs, which integrated in situ and ground-based column observations, mobile surveys, aircraft measurements, and satellite data across complementary spatial and temporal scales. Ground-based measurements confirmed sustained CO₂ enhancements of 27.72 ppm above background concentrations within the DPIC and observed frequent downwind transport of emissions beyond the complex boundary. Mobile measurements identified combined signatures of combustion-linked emissions and fugitive methane releases at the two largest-emitting facilities, while aircraft emission ratio characteristics corroborated these findings, revealing methane leakage concentrated in the DPIC center alongside increased combustion activity. An annual GHG emission rate of 2,595.45 ± 333.09 GgCO₂eqyr^–1 derived from the two largest-emitting facility hotspots alone accounted for approximately 37.1 % of the nationally reported inventory values, suggesting systematic underestimation of bottom-up accounting frameworks, especially of fugitive methane. Satellite observations further identified methane enhancements in access-restricted areas consistent with ground-based measurements. This study demonstrates that coordinated multi-platform observation strategies provide critical constraints for atmospheric emission verification and a scalable framework for improving the accuracy of the quantification of greenhouse gas emissions in complex industrial environments.