Improved representation of boreal fire emissions for the ICARTT period S. Turquety, D. J. Jacob, J. A. Logan, R. M. Yevich, R. C. Hudman, F. Y. Leung, R. M. Yantosca, C. L. Heald, L. K. Emmons, D. P. Edwards, and the INTEX Science Team Burning in boreal forests of Canada or Siberia can have a large impact on an hemispheric scale, and on air quality in the US Burning in boreal regions expected to increase as a result of climate change 2004 fire season in North America: worst fire season in Alaska on record! : 2.6 million hectares burned, > 8 x 10-year average 15 x average area burned in Yukon Territory (60% of national total) 6 x average in British Columbia Solène Turquety – ICARTT Meeting August 10, 2005 US National Interagency Fire Center Canadian Interagency Forest Fire Center

Strong perturbation from the 2004 Alaskan and Canadian fires Solène Turquety – ICARTT Meeting August 10, 2005 Strong signatures in the ICARTT observations Pfister et al., 2005 : 30 ± 5 Tg CO from the fires based on a MOPITT top-down analysis North American anthropogenic emissions: 26.5 Tg CO (US: EPA NEI 99, Canada: GEIA scaled to 1998 using CO2 trends) AIRS/Aqua total CO 18/07/2004 MOPITT total CO 16-18/07/2004 TOMS Aerosol Index 18/07/2004 DC8 flight 18/07/2004 CO DACOM (G. W. Sachse)

Daily variability of the area burned in North America during the summer 2004 Solène Turquety – ICARTT Meeting August 10, 2005 Location of the fires: MODIS hotspot detection Temporal variability: daily reports from the U.S. National Interagency Fire Center Alaska-Yukon [ W]North-Central Canada [125-90W] Day since

Solène Turquety – ICARTT Meeting August 10, 2005 Fuel loadings: × = Include contribution from peat burning Above ground only Potential emissions per unit area Derive emissions for 10 species, with 1x1 horizontal resolution: NOx, CO, lumped >= C4 alkanes, lumped >= C3 alkenes, acetone, methyl ethyl ketone, acetaldehyde, propane, formaldehyde, and ethane. Fraction of peat x 64 tons DM / hectare Emission factors CO: Potential emission CO / hectare burned: Fraction of peat x tons CO/ tons DM

CO emissions, summer 2004 – Above ground burning only Solène Turquety – ICARTT Meeting August 10, Tg CO emitted only considering above ground burning, increase to 31.5 Tg CO if peat burning is included (Yevich and Logan climatology : 9 Tg CO) Pfister et al., 2005 : 30 ± 5 Tg CO based on MOPITT top-down analysis Climatological emissions Yevich and Logan 2004 fire season, above ground burning only 2004 fire season, including peat burning Variability – Alaska-Yukon [ W] CO emissions, summer 2004 – Contribution from peat burning Daily inventory of the 2004 biomass burning emissions

Importance of injection height Solène Turquety – ICARTT Meeting August 10, 2005 Variability max TOMS AI – Alaska-Yukon [ W] TOMS AI depends on both optical depth and altitude of the aerosol plume Peaks in TOMS AI suggest “pyro-convection” events: end of June, beginning of July, mid-July and mid-August Average vertical distribution of boreal fires emissions in the CTM: 40% boundary layer 55% FT ~ [600–400hPa] 5% UT ~ [400–200hPa]

Consistency with atmospheric observations of CO Solène Turquety – ICARTT Meeting August 10, 2005 MOPITT Total CO Summer 2004 GEOS-Chem Total CO x MOPITT AK BB incl. peat (MOPITT – GOES-Chem)/MOPITT BB above ground Including the contribution of peat burning in Alaska and Canada improves comparisons Distribution of peat uncertain Fuel and consumption factors associated with peat burning uncertain CO emissions, summer 2004 – Contribution from peat burning

Consistency with atmospheric observations of CO Solène Turquety – ICARTT Meeting August 10, 2005 MOPITT GEOS-Chem – BB above ground only GEOS-Chem – Incl. peat burning Including the contribution of peat burning in Alaska and Canada improves comparisons Overestimate emissions in Alaska in July Contribution of peat overestimated in July / underestimated in August? Expect more important peat burning efficiency later in the fire season

Consistency with atmospheric observations of CO Solène Turquety – ICARTT Meeting August 10, 2005 Sensitivity to injection heights - July 17-19, 2004 Strong sensitivity of comparisons between model and MOPITT observations to altitude of injection Magnitude of the emissions and injection height need to be considered in parallel Injection in the upper troposphere limited to explosive convection events : introduce time-varying injection heights MOPITT Total COGEOS-Chem Total CO – BB 100% BL GEOS-Chem Total CO – BB 40% BL + 55% FT + 5% UT GEOS-Chem Total CO – BB 30% BL + 40% FT + 30% UT

Solène Turquety – ICARTT Meeting August 10, 2005 Consistency with ICARTT observations of CO DC8 CO observations (DACOM, Glen W. Sachse) Average over the whole mission P3 CO observations (John Holloway NOAA AL ) Average over the whole mission 12km Simulation overestimate CO below 3km: attributed to an overestimate of the US anthropogenic emissions Low sensitivity to BB emissions in the average profiles 7km Observations GEOS-Chem (BB above ground only) GEOS-Chem (BB incl. peat burning) Mean Median

Solène Turquety – ICARTT Meeting August 10, 2005 Summary – Future work 5 million hectares burned in North America during the summer 2004: 2.3 million hectares in Alaska, 2.5 million hectares in Canada (~1.5 million in Yukon Territory) 31.5 Tg CO emitted, 10 Tg CO corresponding to the contribution from peat burning (close to the 30 ± 5 Tg CO from MOPITT top-down analysis of Pfister et al., 2005) Comparisons with MOPITT suggests an overestimate of the emissions in Alaska- Yukon in July TOMS AI suggest that strong pyro-convective events could have occurred, injecting particles and trace gases into the free to upper troposphere Injection height must be considered in parallel in order to evaluate the impact of forest fire emissions on chemical composition of the troposphere Use atmospheric observations to improve our representation of the boreal fire emissions using inverse modeling techniques

Solène Turquety – ICARTT Meeting August, 2005 …