抄録
We used ozone (O3) and carbon monoxide (CO) measurements conducted at Rishiri Island, a remote surface site located in northern Japan to characterize impacts of boreal forest fires in Siberia on photochemical O3 formation. Hourly O3 observations during severe fire seasons in 1998, 2002, and 2003 were examined based on large enhancement in the CO mixing ratios and backward trajectories. In total, we identified sixteen episodes impacted by Siberian biomass burning. Correlations of O3 to CO in individual plumes were significant in eight wildfire plumes. The relative enhancement of O3 to CO quantified in these fire plumes ranged from slightly negative to up to ∼0.4, depending on episodes. Two episodes in 2002 and 2003 suggested that O3 formation in wildfire-polluted plumes was comparable to the magnitude typically observed in industrially-polluted air masses from the Asian continent. Possible physical, chemical, and biogeochemical factors leading to different O3 to CO ratios were presented.
