Verification of Ship Plumes Modelling and Their Impacts on Air Quality and Climate Change in QUANTIFY EC 6FP Project
The impact of emission from transportation on climate change is being quantified in EC FP6 Integrated Project QUANTIFY. In Activity 2 the analysis of the dilution and transformation of the emission from microscale at exhausts and plumes till mesoscale distribution will be provided from all modes of transportation. In this contribution the mesoscale simulations of ship emission impact on atomspheric pollution are studied with emphasis to compare the simulation with reality analyzed by means of flight measurement during the field campaign. In framework of the project the modeling studies are supposed to support the field campaign as well. The sensitivity of the impact on air quality and composition is analyzed as well with respect to ship emissions.
Here the couple of non-hydrostatic model MM5 (PSU/NCAR) and Eulerian model CAMx (ENVIRON International Corporation, 2006) is used to support the measurement campaign. This couple with double nesting enables very high resolution both in meteorological conditions and chemistry in the region of interest, with outer domain of resolution 36 × 36 km, inner one with resolution 12 × 12 km covering the Channel. Meteorological fields generated by MM5 drive CAMx transport and dry/wet deposition. There are problems with the emission inventories available, emissions from EMEP 50 × 50 km database are interpolated and represent average ship emissions in the Channel, other emissions are combination of EMEP and UAEI (United Kingdom Atmospheric Emission Inventory). In our setting CB-IV chemistry mechanism is used (Gery et al., 1989). To see the impact of ships emission on the chemical composition at the surface we present here sensitivity test on outer domain simulation. In Figure 1 ship corridors are well visible in ozone concentration field and the simulations clearly identify impact of ships emission on the chemical composition at the surface.
The performance of the couple was tested first on pre-project campaign data (provided by H. Schlager). This pre-project campaign off-line test shows reasonable comparison between simulation and flight measurement. There are results for O3 displayed in Figure 2, where very good agreement can be seen in ship corridor low level flight, out of it the disagreement is due to the limited extent of CAMx coverage, it covers rather boundary layer processes. Another limitation is valid as the model is not working with actual emission data of individual ships but involving some average emission in model grid. Thus, resulting concentrations represent rather the average value across the grid and the comparison of ship corridor background in the flight measurement is more appropriate. Individual peaks of NO concentration from the individual ship stacks captured by flight measurement cannot be resolved by the model (not shown), better comparison is provided when more complex chemical processes on longer time scale undergone.