We investigate rapid around-the-world transport of a
smoke aerosol plume released by intense forest fires in southeastern Australia in December 2006. On 14 December 2006, a passing cold front in combination with the intense heat from the fires causing pyro-convective lofting, injected a large mass of aerosol particles into the jet stream. We track the resulting aerosol plume using Aerosol Absorbing Index (AAI) observations from the Ozone Monitoring Instrument (OMI) and find that it circumnavigated the world in 12 days. Using observations from OMI and the CALIOP (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) spaceborne lidar, we show that the plume resided in the high troposphere at different stages of its evolution. In absence of CALIOP data, we explored OMI O2-O2 pressures to obtain information on the aerosol plume height.
The observed two-dimensional evolution of the smoke
aerosol plume and the vertical distribution of the plume detected by CALIOP is matched by simulations with the TM4 chemistry transport model for an injection height of 248 hPa (~10 km). Injection heights at the surface and at 540 hPa (~5 km) resulted in simulated vertical distributions
that were 2-3 km too low relative to CALIOP
observations, and showed less agreement with the AAI
patterns. The high injection altitude of 10 km mimics the effect of pyro-convective lofting as the additional buoyancy from the intense fires is not accounted for in the model. This is the first detailed study of around the world long-range transport of forest fire emissions in the
extratropical Southern Hemisphere.
RJ Dirksen, KF Boersma, ATJ de Laat, P Stammes. Three dimensional OMI observations of rapid around the world transport of an aerosol plume released from the Australian forest fires on 14 December 2006.
2009, 2009, KNMI, RIVM, TU Delft