Regional variability in black carbon and carbon monoxide ratio from long-term observations over East Asia: assessment of representativeness for black carbon (BC) and carbon monoxide (CO) emission inventories

Abstract. The BC/CO emission ratios were estimated and compiled from long-term, harmonized observations of the ΔBC/ΔCO ratios under conditions unaffected by wet deposition at four sites in East Asia, including two sites in Korea (Baengnyeong and Gosan) and two sites in Japan (Noto and Fukuoka). Extended spatio-temporal coverage enabled estimation of full seasonality and elucidation of the emission ratio in North Korea, for the first time. The estimated ratios were used to validate the Regional Emission inventory in Asia (REAS) version 2.1 based on six study domains (East China, North China, Northeast China, South Korea, North Korea, and Japan). We found that the ΔBC/ΔCO ratios from four sites converged into a narrow range (6.2–7.9 ng m−3 ppb−1), suggesting consistency in the results from independent observations and similarity in source profiles over the regions. The BC/CO ratios from th…