P. Viaene

The impact of model resolution on simulated ambient air quality and associated human exposure

A simple numerical experiment to evaluate the influence of model resolution on estimates of ambient air quality and associated human exposure is presented. This is done based on annual mean NO2 concentration fields for the agglomeration of Brussels and surroundings, simulated by the deterministic urban/regional-scale AURORA model at a resolution of 1 km. These NO2 concentration fields were used to calculate domain-wide exposure, which is defined here as the population density-weighted concentration. It was found that exposure decreased by 38% when degrading the resolution of the model from 1 to 64 km. A straightforward analysis revealed that this exposure reduction could be explained by the covariance between the concentration and population density patterns.

A Framework for Integrated Assessment Modelling

“Air quality plans” according to Air Quality Directive 2008/50/EC Art. 23 are the strategic element to be developed, with the aim to reliably meet ambient air quality standards in a cost-effective way. This chapter provides a general framework to develop and assess such plans along the lines of the European Commission’s basic ideas to implement effective emission reduction measures at local, region, and national level. This methodological point of view also allows to analyse the existing integrated approaches.

Two Illustrative Examples: Brussels and Porto

To evaluate in practice how IAM can be used to formulate and improve current air quality plans, this chapter reports on the application of one of the existing IAM tools, to two test cases: one for the Brussels Capital Region in Belgium and the other to the region of Porto in the North of Portugal. The two cases are representative for the two options that are available for the decision pathway in the IAM framework as presented in Chap. 2: the scenario evaluation and the optimisation. Before presenting the peculiarities and the results obtained for the two test cases, this chapter briefly describes the specific features of the IAM tool used, namely RIAT+.

Assessment of Damage to Vegetation in Belgium Based on an Ozone Flux Model Approach

Elevated tropospheric ozone concentrations are not only harmful for human health, but they may also have detrimental effects on vegetation. Currently, an ozone exposure index (AOT40) and critical levels for the protection of vegetation have been agreed upon at European level based on the atmospheric ozone concentration and exposure time. Plants are however mainly affected by the ozone actually interacting with the plant tissue which could well be only a small part of the available ozone. Methods have therefore been developed for estimating ozone uptake by plants and to obtain reliable dose-response relationships based on the ozone flux. In this chapter we present a modelling procedure that integrates the DO3SE model for calculating the phytotoxic ozone dose with ECMWF meteorology and ground level ozone concentration maps to produce estimates of the ozone impact on yield and biomass accumulation of crops, forest trees and grassland. The procedure is applied to a Belgium for the year 2009 and compared with the results published for EMEP and used to quantify the impact of ozone on potato and wheat crop yields in 2009.

Application of a Comprehensive Integrated Assessment Tool for the Brussels Capital Region

While in general air quality has improved in Europe over the past decades, there are still problems with exceedances of ambient air quality limit values in many urban areas. To design efficient Air Quality Plans to face these problems, methodologies and tools are required to assess the effects of possible abatement measures on local air quality. One such tool is RIAT+ (http://www.riatplus.eu) which was designed to help regional decision makers select air pollution reduction policies that will improve the air quality at minimal costs. In this contribution to ITM we present the results obtained as well as the lessons learned for an application of the RIAT+ tool to the Brussels Capital Region. RIAT+ has been previously applied successfully to regions in the Po Valley in Italy and to the Alsace region in France. The application to the BCR however poses specific challenges due to the fact that both the area on which the abatement measures can be applied as the emissions are more limited than in previous cases. Inside the BCR, emissions of nitrogen oxide and particulate matter are mainly from non-industrial combustion and traffic. For these two source categories a list of possible air quality abatement measures was provided by the Brussels Environmental agency. To allow RIAT+ to determine the optimal combination of abatement measures with minimal cost, information was collected on both the emission reduction efficiency and the costs of each of these measures. RIAT+ efficiently calculates concentration changes from emission changes using a receptor model based on an artificial neural network. Input for this receptor model was obtained from the results of a validated AURORA chemical transport model setup for the BCR. Once the receptor model was validated, RIAT+ was then used to calculate the effect of the different proposed abatement measures on air quality.

Can Aircraft-Based Remote-Sensing NO 2 Measurements Combined with High Resolution Model Data Improve NO 2 Exposure Estimates over Urban Areas?

As part of the STEREO-III BUMBA (Belgian Urban NO2 Monitoring Based on APEX hyperspectral data) project, we try to exploit the synergy between NO2 column measurements derived from the aircraft-based APEX hyperspectral imaging system and high-resolution model data from a combined land use regression-Gaussian plume model system for the complex city-port region of Antwerp (Belgium). The resulting model maps are then used to determine the NO2-exposure of the population of the region.

Comparing Different Modeling Approaches in Obtaining Regional Scale Concentration Maps

We studied and compared different operational modeling techniques that are used to generate regional scale concentration maps for PM10, PM2,5, NO2 and O3 over Belgium. The various techniques and resulting maps were analyzed, validated and compared aiming at identifying the best possible regional scale concentration map for each pollutant. A distinction was made between a temporal and a spatial validation. The temporal analysis revealed that an intelligent interpolation technique based on land use characteristics in general performs best in capturing the temporal aspects of air quality in Belgium for the investigated pollutants. For PM10 and PM2.5 this technique also performs best in generating the spatial pattern of the observed annually averaged concentrations. A deterministic model combined with a corrective ‘Optimal Interpolation’ data assimilation technique performs best in reproducing the spatial pattern of O3. For NO2 the interpolation technique manages best in explaining the spatial pattern of the observed annually averaged concentrations in Belgium, but when restricted to the region of Flanders, it competes with a thoroughly calibrated Lagrangian type of modeling.

ATMOSYS: A Policy Support System for Atmospheric Pollution Hot Spots

The LIFE + Environmental Policy & Governance project ATMOSYS has the objective to implement an advanced and comprehensive air quality modeling system as a web-based service used by policy makers. The ATMOSYS system is based on advanced technology, including prognostic 3-D atmospheric computer models, data assimilation techniques, CFD modeling, and on results from recent and on-going national and European research projects. Its comprehensive character resides in the multiple scales and scale interactions covered by the system and in a coherent approach for forecasts, assessments, and scenario studies alike.