A case study of pyro-convection using transport model and remote sensing data
Other literature type
Eloranta, E. W.
Razenkov, I. A.
(issn: 1680-7324, eissn: 1680-7324)
Summer 2004 saw severe forest fires in Alaska and the Yukon Territory that
were mostly triggered by lightning strikes. The area burned (>2.7×10<sup>6</sup> ha) in the year 2004 was the highest on record to date in Alaska. Pollutant
emissions from the fires lead to violation of federal standards for air
quality in Fairbanks.
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This paper studies deep convection events that occurred in the burning
regions at the end of June 2004. The convection was likely enhanced by the
strong forest fire activity (so-called pyro-convection) and penetrated into
the lower stratosphere, up to about 3 km above the tropopause. Emissions
from the fires did not only perturb the UT/LS locally, but also regionally.
POAM data at the approximate location of Edmonton (53.5° N, 113.5° W)
show that the UT/LS aerosol extinction was enhanced by a factor of 4
relative to unperturbed conditions. Simulations with the particle dispersion
model FLEXPART with the deep convective transport scheme turned on showed
transport of forest fire emissions into the stratosphere, in qualitatively
good agreement with the enhancements seen in the POAM data. A corresponding
simulation with the deep convection scheme turned off did not result in such
deep vertical transport. Lidar measurements at Wisconsin on 30 June also
show the presence of substantial aerosol loading in the UT/LS, up to about
13 km. In fact, the FLEXPART results suggest that this aerosol plume
originated from the Yukon Territory on 25 June.