INFLUENCE OF BOREAL FOREST FIRES ON AEROSOLS IN THE UPPER TROPOSPHERE AND LOWER STRATOSPHERE

1. INFLUENCE OF BOREAL FOREST FIRES ON AEROSOLS IN THE UPPER TROPOSPHERE AND LOWER STRATOSPHERE Richard Damoah; Nicole Spichtinger; Andreas Stohl Technical University of Munich (TUM) Germany PARTS Meeting Hyytiala, Finland 18 – 21 May 2003

2. Overview • Introduction • Climatical conditions • Seasonal variations of forest fire emissions • Methodology • Model used • Results • Case Studies • Conclusion

3. Why are boreal forest fires so important ?

4. Deforestation • Boreal Region has about 1b ha of closed forest (2/3 in Russia and 1/3 in North America). [Kasischke et al.,2000] • In 1998 ~5 M ha destroyed in Russia (highest in 10yrs) and ~4.5 M ha destroyed in Canada (higest in 5yrs) [IFFN, 1999 , 2000] • Sea • Large amounts of ashes were transported into Okhotsk sea and Japanese sea during • 1998 fire season.[ IFFN, 2000] • Atmosphere • Emit aerosols and trace gases such as CO, NOx and hydrocarbons which leads • to the formation of O3[Goode et al., 2000] • These species can be transported over long distances [Forster, 2001; Spichtinger, 2001]

5. NOAA NCDC SSMI anomaly blended temperature July 1998 July 1997 Climatical condition

6. Seasonal total O3 concentration in the Northern Hemisphere ( > 50°N ) as seen by Global Ozone Monitoring Experiment ( GOME )

7. Seasonal CO2 and CO anomaly averaged over lat. > 30°N from 1996 to 1999.

8. Methodology • SAGE II data were used to detect plumes of enhanced aerosols • Lagrangian transport model FLEXPART was used to trace the sources of the aerosol • enhancement • Finally ATSR hot spot data were used to verify any fire event in source regions.

9. Model Overview • FLEXPART [Stohl et al.,1998; Stohl and Thomson, 1999] is a Lagrangian particle dispersion model that treats both advection and turbulent diffusion by calculating the trajectories of a multitude of particles. • It has recently been equipped with convection scheme [Emanuel and Zivkovic-Rothman, 1999] to account for the sub-gridscale convective transport. • The model is driven by meteorological data from ECMWF [ECMWF, 1995] (resolution 5°, and 31 vertical levels). • FLEXPART can be used in the forward mode to simulate the dispersion of polutants from a location, • or in the backward mode to determine the source - receptor relationship. • In the backward mode, the output is in the unit of seconds known as the residence time, which is a measure of the potential contribution of sources of a certain species to the mixing ration at the receptor.

10. Results SAGE II data averaged over Siberia ( lat. 50°- 60° N ; long. 120°E – 140°E) during the burning season ( May – October)

11. tropopause CASE ONE; 3 – 8 Aug. 1998

12. tropopause CASE TWO; 21 – 26 Sept. 1998

13. tropopause CASE THREE; 10 – 15 Octo. 1998

14. Conclusions • ATSR detected a strong burning season in 1998 in Russia • SAGE II and TOMS data indicate aerosol enhancements over Russia • during the 1998 fire season • FLEXPART simulation shows a strong linkage between the enhanced • aerosols and the forest fires