The impact of traffic emissions on atmospheric ozone and OH: results from QUANTIFY P. Hoor1, J. Borken-Kleefeld2, D. Caro3, O. Dessens4, O. Endresen5, M. Gauss6, V. Grewe7, D. Hauglustaine3, I. S. A. Isaksen6, P. Jöckel1, J. Lelieveld1, G. Myhre6,8, E. Meijer9, D. Olivie10, M. Prather11, C. Schnadt Poberaj12, K. P. Shine13, J. Staehelin12, Q. Tang11, J. van Aardenne14, P. van Velthoven9, and R. Sausen7 1Max Planck Institute for Chemistry, Dept. of Atmospheric Chemistry, 55020 Mainz, Germany 2Transportation Studies, German Aerospace Center (DLR), Berlin, Germany 3Laboratoire des Sciences du Climat et de l'Environment (LSCE), CEN de Saclay, Gif-sur-Yvette, France 4Centre for Atmospheric Science, Dept. of Chemistry, Cambridge, UK 5DNV, Det Norske Veritas (DNV), Oslo, Norway 6Dept. of Geosciences, University of Oslo, Norway 7Deutsches Zentrum für Luft- und Raumfahrt, Inst. für Physik der Atmosphäre, Oberpaffenhofen, 82234 Wessling, Germany 8Center for International Climate and Environmental Research-Oslo (CICERO), Oslo, Norway 9Royal Netherlands Meteorological Institute, KNMI, De Bilt, The Netherlands 10Meteo France, CNRS, Toulouse, France 11Department of Earth System Science, University of California, Irvine, USA 12Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology, Zürich, Switzerland 13Department of Meteorology, University of Reading, UK 14Joint Research Center, JRC, Ispra, Italy
Abstract. To estimate the impact of emissions by road, aircraft and ship traffic on
ozone and OH in the present-day atmosphere six different atmospheric chemistry
models have been used. Based on newly developed global emission inventories for road, ship and
aircraft emission data sets each model performed sensitivity simulations reducing the
emissions of each transport sector by 5%.
The model results indicate that on global annual average lower tropospheric
ozone responds most sensitive to ship emissions (50.6%±10.9% of the total traffic induced
perturbation), followed by road (36.7%±9.3%) and aircraft exhausts (12.7%±2.9%), respectively. In the northern upper
troposphere between 200–300 hPa at 30–60° N the maximum impact from road and ship are
93% and 73% of the maximum effect of aircraft, respectively. The latter is 0.185 ppbv
for ozone (for the 5% case) or 3.69 ppbv when scaling to 100%. On the global
average the impact of road even dominates in the UTLS-region. The sensitivity
of ozone formation per NOx molecule emitted is highest for aircraft exhausts.
The local maximum effect of the summed traffic emissions on
the ozone column predicted by the models is 0.2 DU and occurs over the northern
subtropical Atlantic extending to central Europe. Below 800 hPa both ozone and
OH respond most sensitively to ship emissions in the marine lower troposphere
over the Atlantic. Based on the 5% perturbation the effect on ozone can exceed 0.6% close to the marine
surface (global zonal mean) which is 80% of the total traffic induced ozone
perturbation. In the southern hemisphere ship emissions contribute relatively
strongly to the total ozone perturbation by 60%–80% throughout the year.
Methane lifetime changes against OH are affected strongest by ship emissions
up to 0.21 (± 0.05)%, followed by road (0.08 (±0.01)%) and air traffic
(0.05 (± 0.02)%).
Based on the full scale ozone and methane perturbations positive radiative forcings
were calculated for road emissions (7.3±6.2 mWm−2) and for aviation
(2.9±2.3 mWm−2). Ship induced methane lifetime changes dominate over
the ozone forcing and therefore lead to a net negative forcing (−25.5±13.2 mWm−2).
Citation: Hoor, P., Borken-Kleefeld, J., Caro, D., Dessens, O., Endresen, O., Gauss, M., Grewe, V., Hauglustaine, D., Isaksen, I. S. A., Jöckel, P., Lelieveld, J., Myhre, G., Meijer, E., Olivie, D., Prather, M., Schnadt Poberaj, C., Shine, K. P., Staehelin, J., Tang, Q., van Aardenne, J., van Velthoven, P., and Sausen, R.: The impact of traffic emissions on atmospheric ozone and OH: results from QUANTIFY, Atmos. Chem. Phys., 9, 3113-3136, doi:10.5194/acp-9-3113-2009, 2009.