Impact of forest fires, biogenic emissions and high temperatures on the elevated Eastern Mediterranean ozone levels during the hot summer of 2007
Journal article, 2012

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.

air-quality

organic-compound emissions

variability

emep msc-w

deposition

model

heat-wave

isoprene emissions

transport

europe

Author

O. Hodnebrog

University of Oslo

Cicero Senter for klimaforskning

S. Solberg

Norwegian Institute for Air Research (NILU)

F. Stordal

University of Oslo

T. Svendby

Norwegian Institute for Air Research (NILU)

David Simpson

Chalmers, Earth and Space Sciences, Global Environmental Measurements and Modelling

M. Gauss

Norwegian Meteorological Institute

A. Hilboll

Universität Bremen

G. G. Pfister

The Earth and Sun Systems Laboratory

S. Turquety

Pierre and Marie Curie University (UPMC)

A. Richter

Universität Bremen

J. P. Burrows

Universität Bremen

Hacd van der Gon

Netherlands Organisation for Applied Scientific Research (TNO)

Atmospheric Chemistry and Physics

1680-7316 (ISSN) 1680-7324 (eISSN)

Vol. 12 18 8727-8750

Driving Forces

Sustainable development

Subject Categories

Meteorology and Atmospheric Sciences

Roots

Basic sciences

DOI

10.5194/acp-12-8727-2012

More information

Latest update

5/30/2018