Impact of air traffic emissions on airport air quality. Multi-scale modeling, test bed and field measurements
Abstract
Air traffic emissions are playing a significant role in airport air quality. Engine emissions contribute to the ozone and PM formation. There is an emergence of a need to develop advanced numerical tools and airport emission databases for air pollution studies. Field monitoring at airports necessary to support model assessment is still limited in time and space. The French ONERA AIRPUR project has focused on three objectives: emission inventories; dispersion models; field measurements. Results are presented and discussed in this paper. The ground spatial distribution of LTO emissions using realistic aircraft trajectories, aircraft-engine classification by ICAO, fuel flow methodology and diurnal variations of fleet number, is presented and discussed. Exhaust species time evolution is simulated using a chemical-dispersion model. Results show high emissions of NOx during LTO, and a maximum of CO and Hydrocarbons during taxi. Depending on seasons, the NOx lifetime is varying differently; lower concentration is calculated far away from LTO emissions. Longer-lived pollutants such as ozone are formed downstream and require the use of advanced dispersion models. For this reason, two interactive models coupling the micro and the regional scales are developed and used in this work. A 3D CFD model (CEDRE) simulates the flow characteristics around buildings and the dispersion of emissions. CEDRE boundary conditions are provided by the 3D nested dispersion model MEDIUM/MM5, which includes a surface boundary layer chemistry and calculates the concentration of pollutants from the local to the airport vicinities. The CFD results show a tracer accumulation calculated downstream beside terminals, consistent with observations at some mega-airports. Sensibility studies are conducted to highlight the impact of emissions on ozone formation with MEDIUM. Results show that longer-lived species are produced downstream, their concentration depending on NOx, aromatics and VOC released by engines. Evidence of NOx regime is simulated for the ozone formation at and surrounding airports. At the boarding area, during aircraft parking, APU are generally operated for supplementary electrical power supply for cabin cooling or heating. APU emission indices of NOx, CO, HC and PM equipping civil aircraft are still badly known as they are not certified. Emission indices of soot, NOx, CO, CO2, have been measured on test bed for a specific APU consuming kerosene. Results show that APU emissions are comparable to aero-engine indices for gas, but are far more important for soot. Consequently it is expected that APU emissions are potentially important at airports. Finally, real-time continuous measurements of airborne PM, size distribution and number concentration, have been performed at Nice airport-France, along taxiways for 3 days, in summer 2003 using a 13-stage ELPI. Results show that, when road traffic emissions are not transported into the airport, the observed PM concentration does not exceed the French national threshold for PM mass in summer 2003.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AGUFM.A23A0764R
- Keywords:
-
- 0305 Aerosols and particles (0345;
- 4801);
- 0345 Pollution: urban and regional (0305);
- 0365 Troposphere: composition and chemistry;
- 0368 Troposphere: constituent transport and chemistry