Interaction of anthropogenic and natural emission sources during a wild-land fire event – influence on ozone formation

Abstract

Abstract. The objective of this study is to investigate the contribution of biomass burning in the formation of tropospheric O3. Furthermore, the impact of biogenic emissions under fire and no fire conditions is examined. This is achieved by applying the CAMx chemistry transport model for a wild-land fire event over Western Russia (24 April–10 May 2006). The model results are compared with O3 and isoprene observations from 117 and 9 stations of the EMEP network, respectively. Model computations show that the fire episode altered the O3 sensitivity in the area. In particular, the fire emissions increased surface O3 over Northern and Eastern Europe by up to 80% (40–45 ppb). In case of adopting a high fire NOx/CO emission ratio (0.06), the area (Eastern Europe and Western Russia) is characterized by VOC-sensitive O3 production and the impact of biogenic emissions is proven significant, contributing up to 8 ppb. Under a lower ratio (0.025), total surface O3 is almost doubled due to higher O3 production at the fire spots and lower fires' NO emissions. In this case as well as in the absence of fires, the impact of biogenic emissions is almost negligible. Injection height of the fire emissions accounted for O3 differences of the order of 10%, both at surface and over the planetary boundary layer (PBL).