Deliverable D2.4.2, type: Report

Transcription

1 TRANSPHORM Transport related Air Pollution and Health impacts Integrated Methodologies for Assessing Particulate Matter Collaborative project, Large-scale Integrating Project SEVENTH FRAMEWORK PROGRAMME ENV Transport related air pollution and health impacts Deliverable D2.4.2, type: Report Long range transport: contribution of shipping to European air quality Due date of deliverable: project month 24 Actual submission date: project month 24 Start date of project: 1 January 2010 Duration: 48 months Organisation name of lead contractor for this deliverable: DLR Scientists responsible for this deliverable: Dr. J. Hendricks, Dr. M. Righi Revision: [2]

2 D2.4.2 TRANSPHORM Deliverable Contents 1. Introduction 3 2. Global simulations with EMAC/MADE 4 3. Results 4 4. Conclusions 5 References 11 2 of 11

3 Deliverable TRANSPHORM D2.4.2 Report D2.4.2 Long range transport: contribution of shipping to European air quality Mattia Righi 1, Johannes Hendricks 1 1 Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany Abstract One goal of TRANSPHORM task Long range transport: contribution of shipping to European air quality is to quantify the effects of long range intercontinental-scale atmospheric transport of pollutants from the transport sector on European air quality. A particular focus is the potential of ship emissions on the Atlantic Ocean to affect European air quality. This task cannot be accomplished by regional models, whose domains do not cover all relevant regions of ship traffic. We use the EMAC global atmospheric chemistry model with the aerosol module MADE to perform sensitivity runs, in order to estimate the impact of ship emissions on the European air quality, in terms of aerosol mass and number concentration. We find a potentially relevant impact of such emission sources on the aerosol concentration in the European coastal regions and for the TRANSPHORM target cities London and Rotterdam. The effect on continental Europe and on the other target cities (Helsinki, Oslo and Thessaloniki), on the other hand, is found to be not significant. 1. Introduction Simulations with the EMAC/MADE global aerosol model (Section 2; Lauer et al., 2007; Righi et al., 2011) revealed that effects of global ship emissions on the atmospheric aerosol are not only limited territorially to the oceans. The effects are, of course, largest over the oceans, but also the continental aerosol can be affected. An example of this effect simulated with the EMAC/MADE is shown in Figure 1 (left column). The top panel shows the background aerosol sulfate concentration (including all emission sources), whereas the middle and bottom panels show its absolute and relative perturbation due to ship emissions. The example demonstrates how pollutants from shipping can affect the air quality also over the continents, especially near the coastlines, as discussed also by Lauer et al. (2007) and Righi et al. (2011). Hence, long range transport of pollutants from shipping appears to be of significant importance. For comparison, corresponding aerosol perturbations resulting from land transport emissions are mostly confined to regions close to the emission sources. This is shown in Figure 1 (right), for black carbon (BC). The largest impact of land transport related emissions is found near the emission sources in the most densely populated regions of Europe, south-east Asia and the United States. Changes in aerosol concentrations are limited to these regions, and long range transport effects are small. Emissions of pollutants from ship traffic over the Atlantic Ocean are not fully accounted for in regional models because these sources partly lie outside the model domains. This complicates the representation of the full effect of ship emissions on the European particle budget. In this study, in order to estimate the corresponding uncertainties, the EMAC/MADE global aerosol model was used to estimate the impact of remote ship emission sources on the aerosol mass and number concentrations over Europe. In the pilot studies described above, only the total ship-induced particle perturbations were simulated. Within TRANSPHORM task 2.4.2, a detailed quantification of the contribution of the remote emissions to the total shipping effect over Europe was achieved. The simulations performed, as along with the corresponding results, are described in this report. 3 of 11

4 D2.4.2 TRANSPHORM Deliverable 2. Global simulations with EMAC/MADE The global EMAC model system (ECHAM/MESSy Atmospheric Chemistry model; Jöckel et al. 2005, 2006) was applied. It includes the aerosol module MADE (modal aerosol dynamics model; Lauer et al., 2007). The EMAC/MADE model is capable of simulating the global distribution of aerosol mass and number concentration in three different size modes (Aitken, accumulation, and coarse mode). The model also resolves the mass contributions of the major aerosol constituents in the different modes. Details of the EMAC/MADE model set-up are described, for instance, by Lauer et al. (2007) and Righi et al. (2011). Global emission data for the year 2005 was used. It is described in the TRANSPHORM deliverable report D1.3.4 Global emission baseline for 2005 (report on methodology) and choice of projection data 2020/30. Anthropogenic emissions, including those of ocean-going ships, are included according to the Representative Concentration Pathway data (RCP8.5) which were generated to be applied for global simulations within the IPCC framework (Lamarque et al., 2010; Moss et al., 2010). For the present study, a set of 4 simulations was performed. In a reference simulation (REF) all emission sources are included. Then three additional sensitivity runs were performed, in which ship emissions in various regions were switched off, in order to quantify the long range transport effect for this emission source. In the NOSHIP experiment, ship emissions are completely switched off in the model simulation. In the NO15W and NO30W experiments, ship emissions over the Atlantic were switched off, westward of 15 W and 30 W, respectively. The SO 2 emissions for the reference and the NO15W sensitivity experiment are depicted in Figure 2 as an example. The impact of ship traffic on global aerosol concentration is then computed as the difference between the reference simulation and each of the sensitivity experiments: REF NOSHIP gives the total shipping effect; REF NO15W gives the impact of ship emissions westward of 15 W; REF NO30W gives the impact of ship emissions westward of 30 W. The simulations cover a 7-year period ( ), plus a spin-up year (1998) which is excluded from the analysis. For the present study, a T42-L19 configuration was adopted. It corresponds to a horizontal resolution of about 2.8 at the Equator and a vertical grid structure of 19 non-equidistant layers from the surface to 10 hpa (about 30 km). The model dynamics are nudged to meteorological analysis data from the ECMWF (temperature, winds and logarithm of the surface pressure), in order to minimize the differences in atmospheric dynamics when comparing different experiments. 3. Results The ship-induced changes were analyzed with regard to European aerosol concentrations in the lowermost model layer, where the effects of ship emissions are largest and most relevant for air quality issues. Both the aerosol mass and number concentrations were considered. Changes in annual mean aerosol mass concentration are presented in Figure 3. The total shipping effect (left column) as well as the effects of ship emissions westward of 15 W (middle) and 30 W (right) are shown. The Student s t-test was applied to evaluate the statistical significance of changes in concentration with respect to its inter-annual variability. Grid points, where a significant signal (to a 95% confidence level) could not be detected, are masked out in gray in figure. The top panel of Figure 3 highlights the changes in aerosol sulfate (SO 4 ) concentration, which is one of the most relevant pollutants induced by ship traffic. It is related to the comparatively high emissions of SO 2 from this sector, which is then oxidized to form aerosol sulfate. In general, ship emissions have a large impact on the sulfate concentration over Europe, especially in Central and Western Europe and along the coastlines (Figure 3, top-left panel), with contributions in the range 4 of 11

5 Deliverable TRANSPHORM D2.4.2 of g/m 3. The long range transport effects (Figure 3, top-middle and top-right panel), in particular, occur in the coastal regions. Ship emissions westward of 15 W also have an impact over the UK and Ireland and partly over the Netherlands. The TRANPSHORM target cities (London, Rotterdam, Helsinki, Thessaloniki and Oslo) are indicated by black dots. Important long range transport effects on the sulfate concentration are simulated only for the London and Rotterdam areas. The annual-mean long range contributions to total ship induced sulfate in the grid-boxes containing these cities amount to about 10-20%. The highest (lowest) values are found in summer (winter) months (see Table 1). A similar picture can be drawn for the PM 2.5 concentration (bottom panel of Figure 3). Again the overall ship impact over Europe is the largest along the coastlines, with contributions of about g/m 3. Long range transport effects (bottom-middle and bottom-right panel of Figure 3) are relevant only in the case where ship emissions westward of 15 W are considered. These affect Germany and Eastern Europe. Among the TRANSPHORM target cities, only London and Rotterdam show significant effects (see also Table 2) and, as in the case of sulfate, summer (winter) months are characterized by the highest (lowest) values. The effect of ships westward of 30 W on the European PM 2.5 concentration is too small to be detectable in these model runs. The aerosol module MADE also allows for simulating aerosol particle number concentration. The ship impact on the particle number concentration is highlighted in Figure 4. Both the total number concentration (Figure 4, top) and number concentration of particles larger than 0.1 m (Figure 4, bottom) were considered. Important effects of ship emissions on the particle number are simulated for large areas of the European continent, with largest changes on the order of particles/cm 3 along the coastlines (left column, Figure 4). Compared to the mass concentration, the particle number concentration seems to be more sensitive to long range transport effects. The effect of emissions westward of 15 W (middle column, Figure 4) is significant. The impacts occurred not only along the western coastline, but they extended also to northern Europe along the coastline of the Scandinavian Peninsula. This is observed in particular, when the total number concentration (top panel) is considered. Long range transport contributions to the total ship-induced aerosol number of several 10% are simulated. The effect of emissions westward of 30 W (right column, Figure 4), is less pronounced, but still significant along most of the western and northern European coastlines. On the other hand, no significant long range transport effects on number concentrations are found in the grid-boxes containing the target cities. 4. Conclusions In conclusion, the results of the global simulations reveal that long range transport of pollutants released over the remote Atlantic Ocean can have an important impact (of about 10-20% on annual average) on large-scale mean surface level concentrations of particulate matter along the European coastlines. Among the TRANSPHORM target cities, particularly the background concentrations of London and Rotterdam seem to be affected by such long range transport effects. In this context, it should be mentioned that the model cannot resolve the local concentrations within the cities, which could be much higher than the background. The effects on continental European areas, in general, are small. These results were a motivation, among others, for providing boundary conditions to the regional models in the framework of TRANSPHORM. The boundary condition data are generated using EMAC/MADE, with the same setup adopted for this study, and include aerosol and selected gas species from both anthropogenic (traffic and non-traffic) and natural (dust, sea-salt) sources. The simulations are performed for present-day conditions (year 2005) and two future scenarios (2020 and 2030). The data have already been tested by regional modelers and are currently used to perform simulations on European scales. Studies to assess the sensitivity to different sets of boundary conditions are planned. 5 of 11

6 D2.4.2 TRANSPHORM Deliverable Figure 1: Multi-year average of the impact of ship emissions on the aerosol sulfate concentration (left column) and of road traffic emissions on the black carbon (BC) concentration (right column) at the surface level. The top panel shows the background concentrations, the middle and bottom panels show the absolute and relative changes due to the emissions of ocean-going ships, respectively. Only changes significant at the 95% confidence level (based on Student s t-test) with respect to interannual variability are plotted. Non-significant differences are masked out in white. 6 of 11

7 Deliverable TRANSPHORM D2.4.2 Figure 2: Emission fluxes of SO2 from ship traffic in The top-panel shows the global emissions used in the reference simulation (REF). In the bottom panel, ship emissions over the Atlantic Ocean are switched off westward of longitude 15 W (NO15W). The analogous case for 30 W (NO30W) is not shown. 7 of 11

8 D2.4.2 TRANSPHORM Deliverable Figure 3: Multi-year average changes in aerosol sulfate (SO4, top panel) and PM2.5 (bottom panel) concentration due to shipping. The left column shows the total shipping effect, the middle and right columns show the effect of long range transport from ship emissions westward of longitude 15 W (difference between simulations REF and NO15W) and 30 W (difference between simulations REF and NO30W). Only changes significant at the 95% confidence level (based on Student s t-test) with respect to inter-annual variability are plotted. Non-significant differences are masked out in gray. The dots indicate the location of the TRANSPHORM target cities. 8 of 11

9 Deliverable TRANSPHORM D2.4.2 Figure 4: As Figure 3, but for the total particle number concentration (top panel) and the number concentration of particles with diameter larger than 0.1 Pm (bottom panel). 9 of 11

10 D2.4.2 TRANSPHORM Deliverable All ships Ships westward of 15 W Annual DJF JJA Annual DJF JJA Helsinki Rotterdam Oslo Thessaloniki London Table 1: Impact of ship emissions on aerosol sulfate mass concentration [µg/m 3 ] in the TRANSPHORM target cities. Non-significant values are excluded. All ships Ships westward of 15 W Annual DJF JJA Annual DJF JJA Helsinki Rotterdam Oslo Thessaloniki London Table 2: As for Table 1, but for PM of 11

11 Deliverable TRANSPHORM D2.4.2 References Jöckel, P., Sander, R., Kerkweg, A., Tost, H., Lelieveld, J., 2005: Technical Note: The Modular Earth Submodel System (MESSy) a new approach towards Earth System Modeling, Atmos. Chem. Phys., 5, Jöckel, P., Tost, H., Pozzer, A., Brühl, C., Buchholz, J., Ganzeveld, L., Hoor, P., Kerkweg, A., Lawrence, M. G., Sander, R., Steil, B., Stiller, G., Tanarhte, M., Taraborrelli, D., van Aardenne, J., Lelieveld, J., 2006: The atmospheric chemistry general circulation model ECHAM5/MESSy1: consistent simulation of ozone from the surface to the mesosphere, Atmos. Chem. Phys., 6, Lamarque, J.-F., et al., Historical ( ) gridded anthropogenic and biomass burning emissions of reactive gases and aerosols: methodology and application, Atmos. Chem. Phys., 10, , Lauer, A., et al, Global model simulations of the impact of ocean-going ships on aerosols, clouds, and the radiation budget, Atmos. Chem. Phys., 7, , Moss, R., et al., The next generation of scenarios for climate change research and assessment, Nature, 463, , Righi, M., et al., Climate impact of biofuels in shipping: global model studies of the aerosol indirect effect, Environ. Sci. Tech., 45, , of 11