2010-01-14: An aerosol boomerang observed from space.
In December 2006 southeastern Australia suffered from severe forest fires. Using the OMI instrument we observed how a smoke plume released by these fires on 14 December rapidly crossed the Pacific and reached southern America only five days later. After passing south America the plume continued its journey over the Atlantic and the Indian Ocean to return to home base on 25 December, making it the first-time observation of rapid around-the-world transport in the extra-tropical southern hemisphere.
This rapid circumnavigation is possible because pyro-convection, lofting by a passing cold-front in combination with the latent heat of the fires, injected the smoke plume high into the free troposphere where it was picked up by the jet-stream and started its high-speed journey. The high altitude of the plume is essential for this event; because of the strong winds and because the very low humidity in this region of the troposphere makes the aerosol particles in the plume less prone to removal by rain-out.
We determined the plume's altitude using the OMI O2-O2 cloud retrieval algorithm and the CALIOP spaceborne LIDAR to be around 10 km. We could quite accurately simulate the observed transport of the plume with the TM4 Chemical Transport Model (CTM). As CTM's typically don't include processes like pyro-convection, the injection height has to be prescribed. We found that an injection height of 248 hPa (10 km) best describes the observed transport. Please read more in
Dirksen et al. 2009.
Around-the-world transport of the smoke plume released by wildfires in
Australia on 14 December 2006. The quantity shown is the AAI from OMI.
The numbers indicate the days in the period 14-25 December 2006. Here is a
movie of the plume.