Ozone production in boreal fire smoke plumes using observations from the Tropospheric Emission Spectrometer and the Ozone Monitoring Instrument

We examine the photochemical processes governing the production of ozone in smoke from large Siberian fires that formed in July 2006 using colocated O-3 and CO profiles as measured by the Tropospheric Emission Spectrometer as well as NO2 and aerosol optical depths as measured by the Ozone Monitoring Instrument. The Real-Time Air Quality Model (RAQMS) is used to explain the observed variations of O3. Enhanced levels of ozone up to 90 parts per billion (ppbv) are observed near and away from the Siberian fires (60 degrees N and 100 degrees E) when sunlight and NOx are available. We also observe significantly low O-3 amounts (less then 30 ppbv) in the smoke plume from Siberian fires in conjunction with optically thick aerosols. Despite this wide variance in observed ozone values, the mean ozone value for all observations of the smoke plume is close to background levels of approximately 55 ppbv in the free troposphere. Using RAQMS we show that optically thick aerosols in the smoke plume can substantially reduce the photochemical production of ozone and this can explain why the observed mean ozone amount for all plume observations is not much larger than background values of 55 ppbv. However, the anonymously low ozone amounts of 30 ppbv or less point toward other unresolved processes that reduce ozone below background levels in the plume.