Observations of atmospheric 14CO2 at Anmyeondo GAW station, South Korea: implications for fossil fuel CO2 and emission ratios

To understand the Korean Peninsula's carbon dioxide (CO₂) emissions and sinks as well as those of the surrounding region, we used 70 flask-air samples collected during May 2014 to August 2016 at Anmyeondo (AMY; 36.53^∘ N, 126.32^∘ E; 46 m a.s.l.) World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) station, located on the west coast of South Korea, for analysis of observed ¹⁴C in atmospheric CO₂ as a tracer of fossil fuel CO₂ contribution (C_ff). Observed ¹⁴C ∕ C ratios in CO₂ (reported as Δ values) at AMY varied from −59.5 ‰ to 23.1 ‰, with a measurement uncertainty of ±1.8 ‰. The derived mean value C_ff of (9.7±7.8) µmol mol⁻¹ (1σ) is greater than that found in earlier observations from Tae-Ahn Peninsula (TAP; 36.73^∘ N, 126.13^∘ E; 20 m a.s.l., 28 km away from AMY) of (4.4±5.7) µmol mol⁻¹ from 2004 to 2010. The enhancement above background mole fractions of sulfur hexafluoride (Δx(SF₆)) and carbon monoxide (Δx(CO)) correlate strongly with C_ff (r>0.7) and appear to be good proxies for fossil fuel CO₂ at regional and continental scales. Samples originating from the Asian continent had greater Δx(CO) : C_ff(R_CO) values, (29±8) to (36±2) nmol µmol⁻¹, than in Korean Peninsula local air ((8±2) nmol µmol⁻¹). Air masses originating in China showed (1.6±0.4) to (2.0±0.1) times greater R_CO than a bottom-up inventory, suggesting that China's CO emissions are underestimated in the inventory, while observed R_SF6 values are 2–3 times greater than inventories for both China and South Korea. However, R_CO values derived from both inventories and observations have decreased relative to previous studies, indicating that combustion efficiency is increasing in both China and South Korea. Since we confirmed the possibility to verify the bottom-up inventories using our measurement data, it will be presented the Korea IG3IS future plan in this presentation.