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Processes influencing ozone levels in Alaskan forest fires plumes during long-range transport over the North Atlantic

Real, E. and Law, K. and Weinzierl, Bernadett and Fiebig, Monika and Petzold, Andreas and Wild, O. and Methven, J. and Arnold, S. and Stohl, Andreas and Huntrieser, Heide and Roiger, Anke and Schlager, Hans and Stewart, D. and Avery, M. and Sachse, G. and Browell, Edward and Ferrare, R. and Blake, D. (2007) Processes influencing ozone levels in Alaskan forest fires plumes during long-range transport over the North Atlantic. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 112 (D10S41), pp. 1-19. DOI: 10.1029/2006JD007576. ISSN 2169-897X.

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Official URL: http://www.agu.org/journals/jd/jd0709/2006JD007576/2006JD007576.pdf

Abstract

A case of long-range transport of a biomass burning plume from Alaska to Europe is analyzed using a Lagrangian approach. This plume was sampled several times in the free troposphere over North America, the North Atlantic and Europe by three different aircraft during the IGAC Lagrangian 2K4 experiment which was part of the ICARTT/ ITOP measurement intensive in summer 2004. Measurements in the plume showed enhanced values of CO, VOCs and NOy, mainly in form of PAN. Observed O3 levels increased by 17 ppbv over 5 days. A photochemical trajectory model, CiTTyCAT, was used to examine processes responsible for the chemical evolution of the plume. The model was initialized with upwind data and compared with downwind measurements. The influence of high aerosol loading on photolysis rates in the plume was investigated using in situ aerosol measurements in the plume and lidar retrievals of optical depth as input into a photolysis code (Fast-J), run in the model. Significant impacts on photochemistry are found with a decrease of 18% in O3 production and 24% in O3 destruction over 5 days when including aerosols. The plume is found to be chemically active with large O3 increases attributed primarily to PAN decomposition during descent of the plume toward Europe. The predicted O3 changes are very dependent on temperature changes during transport and also on water vapor levels in the lower troposphere which can lead to O3 destruction. Simulation of mixing/dilution was necessary to reproduce observed pollutant levels in the plume. Mixing was simulated using background concentrations from measurements in air masses in close proximity to the plume, and mixing timescales (averaging 6.25 days) were derived from CO changes. Observed and simulated O3/CO correlations in the plume were also compared in order to evaluate the photochemistry in the model. Observed slopes change from negative to positive over 5 days. This change, which can be attributed largely to photochemistry, is well reproduced by multiple model runs even if slope values are slightly underestimated suggesting a small underestimation in modeled photochemical O3 production. The possible impact of this biomass burning plume on O3 levels in the European boundary layer was also examined by running the model for a further 5 days and comparing with data collected at surface sites, such as Jungfraujoch, which showed small O3 increases and elevated CO levels. The model predicts significant changes in O3 over the entire 10 day period due to photochemistry but the signal is largely lost because of the effects of dilution. However, measurements in several other BB plumes over Europe show that O3 impact of Alaskan fires can be potentially significant over Europe.

Document Type:Article
Title:Processes influencing ozone levels in Alaskan forest fires plumes during long-range transport over the North Atlantic
Authors:
AuthorsInstitution or Email of Authors
Real, E.CNRS, Paris, F
Law, K.CNRS, Paris, F
Weinzierl, BernadettDLR, IPA
Fiebig, MonikaDLR, IPA
Petzold, AndreasDLR, IPA
Wild, O.Centre for Atmospheric Science, Cambridge, UK
Methven, J.Univ. of Reading, Reading, UK
Arnold, S.Univ. of Leeds, Leeds, UK
Stohl, AndreasNILU, Kjeller, N
Huntrieser, HeideDLR, IPA
Roiger, AnkeDLR, IPA
Schlager, HansDLR, IPA
Stewart, D.Univ.of East Anglia, Norwich, UK
Avery, M.NASA, Hampton, VA, USA
Sachse, G.NASA, Hampton, VA, USA
Browell, EdwardNASA, Hampton, VA, USA
Ferrare, R.NASA, Hampton, VA, USA
Blake, D.Univ. of California, Irvine, CA, USA
Date:2007
Journal or Publication Title:JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
Refereed publication:Yes
In Open Access:No
In SCOPUS:No
In ISI Web of Science:Yes
Volume:112
DOI:10.1029/2006JD007576
Page Range:pp. 1-19
ISSN:2169-897X
Status:Published
Keywords:biomass burning plume, long-range transport, photochemical trajectory modeling, boreal fires
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:other
HGF - Program Themes:other
DLR - Research area:Aeronautics
DLR - Program:L - no assignment
DLR - Research theme (Project):L - no assignment (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Dr.rer.nat. Heidi Huntrieser
Deposited On:14 May 2007
Last Modified:06 Oct 2014 16:55

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