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| Titel |
Impact of forest fires, biogenic emissions and high temperatures on the elevated Eastern Mediterranean ozone levels during the hot summer of 2007 |
| VerfasserIn |
Ø. Hodnebrog, S. Solberg, F. Stordal, T. M. Svendby, D. Simpson, M. Gauss, A. Hilboll, G. G. Pfister, S. Turquety, A. Richter, J. P. Burrows, H. A. C. Denier van der Gon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 18 ; Nr. 12, no. 18 (2012-09-27), S.8727-8750 |
| Datensatznummer |
250011475
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| Publikation (Nr.) |
 copernicus.org/acp-12-8727-2012.pdf |
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| Zusammenfassung |
The hot summer of 2007 in southeast Europe has been studied using two
regional atmospheric chemistry models; WRF-Chem and EMEP MSC-W. The region
was struck by three heat waves and a number of forest fire episodes, greatly
affecting air pollution levels. We have focused on ozone and its precursors
using state-of-the-art inventories for anthropogenic, biogenic and forest
fire emissions. The models have been evaluated against measurement data, and
processes leading to ozone formation have been quantified. Heat wave
episodes are projected to occur more frequently in a future climate, and
therefore this study also makes a contribution to climate change impact
research.
The plume from the Greek forest fires in August 2007 is clearly seen in
satellite observations of CO and NO2 columns, showing extreme levels of
CO in and downwind of the fires. Model simulations reflect the location and
influence of the fires relatively well, but the modelled magnitude of CO in
the plume core is too low. Most likely, this is caused by underestimation of
CO in the emission inventories, suggesting that the CO/NOx ratios of
fire emissions should be re-assessed. Moreover, higher maximum values are
seen in WRF-Chem than in EMEP MSC-W, presumably due to differences in plume
rise altitudes as the first model emits a larger fraction of the fire
emissions in the lowermost model layer. The model results are also in fairly
good agreement with surface ozone measurements.
Biogenic VOC emissions reacting with anthropogenic NOx emissions are
calculated to contribute significantly to the levels of ozone in the region,
but the magnitude and geographical distribution depend strongly on the model
and biogenic emission module used. During the July and August heat waves,
ozone levels increased substantially due to a combination of forest fire
emissions and the effect of high temperatures. We found that the largest
temperature impact on ozone was through the temperature dependence of the
biogenic emissions, closely followed by the effect of reduced dry deposition
caused by closing of the plants' stomata at very high temperatures. The
impact of high temperatures on the ozone chemistry was much lower. The
results suggest that forest fire emissions, and the temperature effect on
biogenic emissions and dry deposition, will potentially lead to substantial
ozone increases in a warmer climate. |
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