Atmospheric Chemistry and Physics
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2007
10.5194/acp-7-5105-2007
http://www.atmos-chem-phys.net/7/5105/2007/
http://www.atmos-chem-phys.net/7/5105/2007/acp-7-5105-2007.html
http://www.atmos-chem-phys.net/7/5105/2007/acp-7-5105-2007.pdf
5105
5127
2007-10-04
Perturbation of the European free troposphere aerosol by North American forest fire plumes during the ICARTT-ITOP experiment in summer 2004
A. Petzold
andreas.petzold@dlr.de
B. Weinzierl
H. Huntrieser
A. Stohl
E. Real
J. Cozic
M. Fiebig
J. Hendricks
A. Lauer
K. Law
A. Roiger
H. Schlager
E. Weingartner
Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Wessling, Germany
Norwegian Institute for Air Research (NILU), P.O. Box 100, 2027 Kjeller, Norway
CNRS Service Aeronomie, Universite Pierre et Marie Curie. 4 Place Jussieu, 75252 Paris Cedex 05, France
Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
During the ICARTT-ITOP Experiment in summer 2004 plumes from large wildfires
in North America were transported to Central Europe at 3–8 km altitude
above sea level (a.s.l.). These plumes were studied with the DLR (Deutsches
Zentrum fuer Luft- und Raumfahrt) research aircraft Falcon which was
equipped with an extensive set of in situ aerosol and trace gas instruments.
Analyses by the Lagrangian dispersion model FLEXPART provided source
regions, transport times and horizontal extent of the fire plumes. Results
from the general circulation model ECHAM/MADE and data from previous aerosol
studies over Central Europe provided reference vertical profiles of black
carbon (BC) mass concentrations for year 2000 conditions with forest fire
activities below the long-term average. Smoke plume observations yielded a
BC mass fraction of total aerosol mass with respect to PM 2.5 of 2–8%.
The ratio of BC mass to excess CO was 3–7.5 mg BC (g CO)<sup>−1</sup>.
Even after up to 10 days of atmospheric transport, both characteristic
properties were of the same order as for fresh emissions. This suggests an
efficient lifting of BC from forest fires to higher altitudes with only
minor scavenging removal of particulate matter. Maximum aerosol absorption
coefficient values were 7–8 Mm<sup>−1</sup> which is about two orders of
magnitude above the average European free tropospheric background value.
Forest fire aerosol size distributions were characterised by a strong
internally mixed accumulation mode centred at modal diameters of
0.25–0.30 µm with an average distribution width of 1.30. Nucleation
and small Aitken mode particles were almost completely depleted.
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