Observations of Smoke from Canadian Forest Fires in the Stratosphere over Florida

Katja Drdla, Max Loewenstein, and Paul Bui

During the Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) campaign, elevated levels of CO were measured in the stratosphere on two flights. The CO enhancements correlated with enhancements in CO2H2O, NOy and particle concentrations, and decreases in O3. Analysis of Particle Analysis by Laser Mass Spectrometer (PALMS) measurements during these events revealed that the particles were primarily carbonaceous, in strong contrast to the typical stratospheric sulphate aerosol. Furthermore, the particles contained enhanced potassium and very few metals, both consistent with past measurements of biomass burning plumes.

Backtrajectory analysis revealed that the sampled air masses had all passed over northern Saskatchewan, Canada, on June 27th, at which point a large number of wildfires were in progress. More than 500 hotspots existed, and more than 190,000 km2 of smoke was created by these hotspots. The presence of smoke was confirmed by Total Ozone Mapping Spectrometer (TOMS) satellite observations, which showed a large region of high aerosol index in the region. The TOMS data tracked the movement of this aerosol to the Southeast U.S. over the next five days, in good agreement with the trajectory analysis. Enhanced aerosol layers were also observed by Polar Ozone and Aerosol Measurement (POAM).

Therefore, these observations demonstrate that material from Canadian forest fires can be injected deep into the stratosphere. Once there, the material can be transported into the tropics, where continued transport higher into the tropics, via the tropical pipe, is very likely. Therefore, soot and other chemicals produced by the wildfires can be spread throughout the stratosphere. These particles may explain past observations of soot throughout the stratosphere, at levels higher than can be explained by aircraft emissions. Further research is necessary to determine the dynamics responsible for injecting forest fire smoke to such high altitudes, and to determine how common these events are.

Collaborators: Hans-Jurg Jost, Bay Area Environmental Research Institute

                          Daniel Cziczo, NOAA

                          Daniel Murphy, NOAA

                          Michael Fromm, Naval Research Laboratory

                          Erik Richard, NOAA

                          Steven Wofsy, Harvard University

                          Robert Herman, Jet Propulsion Laboratory

                          Chuck Wilson, University of Denver

Point of Contact: Katja Drdla, (650) 604-5663, katja@aerosol.arc.nasa.gov