A novel approach to screen and compare emission inventories

A methodology is proposed to support the evaluation and comparison of different types of emission inventories, and more specifically the comparison of bottom-up versus top-down approaches. The strengths and weaknesses of the methodology are presented and discussed based on an example. The approach results in a “diamond” diagram useful to flag out anomalous behaviors in the emission inventories and to get insight on possible explanations. In particular, the “diamond” diagram is shown to provide meaningful information in terms of: discrepancies between the total emissions reported by macro-sector and pollutant, contribution of each macro-sector to the total amount of emissions released by pollutant, and the identification and quantification of the different factors causing the discrepancies between total emissions. Its main strength as an indicator is to allow investigating the relative contribution of activity and weighted emission factors. A practical example in Barcelona is used for testing and to provide relevant information for the analyzed emission datasets. The tests show the capability of the proposed methodology to flag inconsistencies in the existing inventories. The proposed methodology system may be useful for regional and urban inventory developers as an initial evaluation of the consistency of their inventories.JRC.H.2-Air and Climat

EURODELTA - Evaluation of a Sectoral Approach to Integrated Assessment Modeling - Second Report

The EURODELTA project is a continuing collaboration between the European Commission Joint Research Centre (JRC) at Ispra (Italy) and five air quality modeling teams at Ineris (France), the Free University of Berlin (Germany), Met.no (Norway), TNO (Netherlands) and SMHI (Sweden). This phase of Eurodelta investigates how different air quality models would represent the effect on pollutant impacts of applying, on a European scale, emission reductions to individual emission sectors. The reason for doing this is to test whether there are important sensitivities not captured by the sound science approach to air quality policy making on a European scale which is based on an integrated assessment (IA) approach and embodied in the IIASA RAINS/GAINS model. This study shows that there are important differences between sectors in the amount of concentration (deposition) reduction obtained by changing a pollutant emission. This difference is not accounted for in the present process used to evaluate future national emissions ceiling reductions for both beneficial effect and cost-effectiveness. This raises the possibility that, when national bodies consider how to implement an emission ceiling taking account of the information used in deriving that ceiling, choices might be made that are less effective than expected.JRC.DDG.H.4-Transport and air qualit

The Influence of Foreign vs North American Emissions on Surface Ozone in the US

As part of the Hemispheric Transport of Air Pollution (HTAP; www.htap.org) project, we analyze results from 16 global and hemispheric chemical transport models and compare these to Clean Air Status and Trends Network (CASTNet) observations in the United States (US) for 2001. Using the policy-relevant maximum daily 8-h ozone (MDA8 O3) statistic, the multi-model ensemble represents the observations well (mean r2=0.57, ensemble bias=+4.1 ppbv for all regions and all seasons) despite a wide range in the individual model results. Correlations are strongest in the NorthEastern US during spring and fall (r2=0.68); and weakest in the Midwestern US in summer (r2=0.46). However, large positive mean biases exist during summer for all Eastern US regions, ranging from 10¿20 ppbv, and a smaller negative bias is present in the Western US during spring (3 ppbv). In most all other regions and seasons, the biases of the model ensemble simulations are 5 ppbv. Sensitivity simulations in which anthropogenic O3-precursor emissions (NOx+NMVOC+CO+aerosols) were decreased by 20% in each of four source regions: East Asia (EA), South Asia (SA), Europe (EU) and North America (NA) show that the greatest response of MDA8 O3 to the summed foreign emissions reductions occurs during spring in the West (0.9 ppbv reduction due to 20% reductions from EA+SA+EU). East Asia is the largest contributor to MDA8 O3 at all ranges of the O3 distribution for most regions (typically 0.45 ppbv). The exception is in the NorthEastern US where European emissions reductions had the greatest impact on MDA8 O3, particularly in the middle of the MDA8 O3 distribution (response of 0.35 ppbv between 35¿55 ppbv). In all regions and seasons, however, O3-precursor emissions reductions of 20% in the NA source region decrease MDA8 O3 the most by a factor of 2 to nearly 10 relative to foreign emissions reductions. The O3 response to anthropogenic NA emissions is greatest in the Eastern US during summer at the high end of the O3 distribution (5-6 ppbv for 20% reductions). While the impact of foreign emissions on surface O3 in the US is not negligible and is of increasing concern given the growth in emissions upwind of the US - domestic emissions reductions remain a farmore effective means of decreasing MDA8 O3 values, particularly those above 75 ppb(the current US standard).JRC.H.2-Air and Climat

Modeled deposition of nitrogen and sulfur in Europe estimated by 14 air quality model systems: evaluation, effects of changes in emissions and implications for habitat protection

The evaluation and intercomparison of air quality models is key to reducing model errors and uncertainty. The projects AQMEII3 and EURODELTA-Trends, in the framework of the Task Force on Hemispheric Transport of Air Pollutants and the Task Force on Measurements and Modelling, respectively (both task forces under the UNECE Convention on the Long Range Transport of Air Pollution, LTRAP), have brought together various regional air quality models to analyze their performance in terms of air concentrations and wet deposition, as well as to address other specific objectives. This paper jointly examines the results from both project communities by intercomparing and evaluating the deposition estimates of reduced and oxidized nitrogen (N) and sulfur (S) in Europe simulated by 14 air quality model systems for the year 2010. An accurate estimate of deposition is key to an accurate simulation of atmospheric concentrations. In addition, deposition fluxes are increasingly being used to estimate ecological impacts. It is therefore important to know by how much model results differ and how well they agree with observed values, at least when comparison with observations is possible, such as in the case of wet deposition. This study reveals a large variability between the wet deposition estimates of the models, with some performing acceptably (according to previously defined criteria) and others underestimating wet deposition rates. For dry deposition, there are also considerable differences between the model estimates. An ensemble of the models with the best performance for N wet deposition was made and used to explore the implications of N deposition in the conservation of protected European habitats. Exceedances of empirical critical loads were calculated for the most common habitats at a resolution of 100  ×  100 m2 within the Natura 2000 network, and the habitats with the largest areas showing exceedances are determined. Moreover, simulations with reduced emissions in selected source areas indicated a fairly linear relationship between reductions in emissions and changes in the deposition rates of N and S. An approximate 20 % reduction in N and S deposition in Europe is found when emissions at a global scale are reduced by the same amount. European emissions are by far the main contributor to deposition in Europe, whereas the reduction in deposition due to a decrease in emissions in North America is very small and confined to the western part of the domain. Reductions in European emissions led to substantial decreases in the protected habitat areas with critical load exceedances (halving the exceeded area for certain habitats), whereas no change was found, on average, when reducing North American emissions in terms of average values per habitat

Impact of Biogenic Emissions on Ozone in the Mediterranean Area. A BEMA Modelling Study.

Abstract not availableJRC.(EI)-Environment Institut

Air Quality Modelling and Atmospheric Model Evaluation.

Abstract not availableJRC.H-Institute for environment and sustainability (Ispra

The Sensitivity of the CHIMERE Model to Emissions Reduction Scenarios on Air Quality in Northern Italy

The sensitivity of the CHIMERE model to emission reduction scenarios on particulate matter PM2.5 and ozone (O3) in Northern Italy is studied. The emissions of NOx, PM2.5 SO2, VOC or NH3 were reduced by 50% for different source sectors for the Lombardy region, together with 5 additional scenarios to estimate the effect of local measures on improving the air quality for the Po valley area. Firstly, we evaluate the model performance by comparing calculated surface aerosol concentrations for the standard case (no emission reductions) with observations for January and June 2005. Calculated monthly mean PM10 concentrations are in general underestimated by a factor of 1.4 for January, while NO3- and NH4+ calculated monthly mean values are in good correspondence with observations. However, SO4= is underestimated by a factor of 2.4 and the sum of elemental carbon, organic material and anthropogenic dust (PPM) is underestimated by a factor of 3.8 when compared to measurements for January 2005. For June, modelled PM10 concentrations slightly overestimate the measurements by a factor of 1.2 and calculated monthly mean SO4=, NO3-, NH4+ concentrations are in good agreement with the observations. PPM is a factor 2 underestimated. Monthly mean calculated ozone concentrations are in general 12% overestimated when compared to the observations for June 2005. Secondly, the model sensitivity of emission reduction scenarios on PM2.5 and O3 calculated concentrations for the Po valley area is evaluated. The most effective 1 scenarios to abate PM2.5 concentration are based on the SNAP2 (non-industrial combustion plants) and SNAP 7 (road traffic) sectors, for which the NOx and PM2.5 emissions are reduced by 50%. These scenarios reduce the monthly calculated PM2.5 concentrations for January for the Po valley area on average by 4-10µg/m3 and 3-8µg/m3 respectively, with maximum reductions of 13.4µg/m3 and 14µg/m3 respectively, compared to the standard case. The number of days that the 2015 PM2.5 limit value of 25µg/m3 in Milan is exceeded by reducing primary PM2.5 and NOx emissions for SNAP 2 and 7 by 50%, does not change in January when compared to the standard case for the Milan area. From the additional scenarios carried out to investigate the impact of local versus regional air pollution, it appears that 60% of the PM2.5 concentration in the greater Milan area is caused by the emissions from the Lombardy region, while 40% of the PM2.5 concentration over the Milan area is due to the emissions surrounding the Lombardy region and from the model boundary conditions. This study also showed that a more effective pollutant reduction (emissions) per tonne of pollutant reduced (concentrations) for the greater Milan area is obtained by reducing the primary PM2.5 emissions for SNAP 7 by 50%. This scenario is almost four times more efficient than reducing the PM2.5 emissions of SNAP 2 by 50%. Reducing the precursor NOx emissions by 50% is the most effective for SNAP 2 on the decrease of PM2.5 concentrations. The most effective scenario on PM2.5 decrease for which the precursor SO2 emissions are reduced is achieved by SNAP 7. Our study showed that during summer time, the largest reductions in O3 concentrations are achieved for SNAP 7 emission reductions (up to 12 ppb over a larger area around Milan), when volatile organic compounds (VOCs) are reduced by 50%JRC.H.4-Transport and air qualit

Assessment of discrepancies between bottom-up and regional emission inventories in Norwegian urban areas

This study shows the capabilities of a benchmarking system to identify inconsistencies in emission inventories, and to evaluate the reason behind discrepancies as a mean to improve both bottom-up and downscaled emission inventories. Fine scale bottom-up emission inventories for seven urban areas in Norway are compared with three regional emission inventories, EC4MACS, TNO_MACC-II and TNO_MACC-III, downscaled to the same areas. The comparison shows discrepancies in nitrogen oxides (NOx) and particulate matter (PM2.5 and PM10) when evaluating both total and sectorial emissions. The three regional emission inventories underestimate NOx and PM10 traffic emissions by approximately 20 e80% and 50e90%, respectively. The main reasons for the underestimation of PM10 emissions from traffic in the regional inventories are related to non-exhaust emissions due to resuspension, which are included in the bottom-up emission inventories but are missing in the official national emissions, and therefore in the downscaled regional inventories. The benchmarking indicates that the most probable reason behind the underestimation of NOx traffic emissions by the regional inventories is the activity data. The fine scale NOx traffic emissions from bottom-up inventories are based on the actual traffic volume at the road link and are much higher than the NOx emissions downscaled from national estimates based on fuel sales and based on population for the urban areas. We have identified important discrepancies in PM2.5 emissions from wood burning for residential heating among all the inventories. These discrepancies are associated with the assumptions made for the allocation of emissions. In the EC4MACs inventory, such assumptions imply high underestimation of PM2.5 emissions from the residential combustion sector in urban areas, which ranges from 40 to 90% compared with the bottom-up inventories. The study shows that in three of the seven Norwegian cities there is need for further improvement of the emission inventories.JRC.C.5-Air and Climat

Evaluation of MM5, WRF and TRAMPER meteorology over the complex terrain of the Po Valley, Italy

The objective of this study was to evaluate three meteorological models (MM5, WRF and TRAMPER) by comparing the calculated meteorological parameters with observations over the Po Valley area (Italy) for 2005. The analysis shows that MM5 and WRF perform with similar quality, with advantages of WRF at following high resolution time patterns and better scores of MM5 at reproducing annual averages, noticed for precipitation and relative humidity calculations. Results from the TRAMPER model also reflect very well surface meteorological measurements, they may be however driven by data assimilation applied in this modelling system and thus strongly influenced by very local effects. This feature of TRAMPER may lead as well to large uncertainties in reproducing other parameters important for air quality modelling such as planetary boundary layer (PBL) heights, friction velocity (u*) values or stability conditions.JRC.H.2-Air and Climat

The Sensitivity of Aerosol in Europe to two Different Emission Inventories and Temporal Distribution of Emissions

The sensitivity to two different emission inventories, injection altitude and temporal variations of anthropogenic emissions in aerosol modelling is studied, using the two way nested global transport chemistry model TM5 focussing on Europe in June and December 2000. The simulations of gas and aerosol concentrations and aerosol optical depth (AOD) with the EMEP and AEROCOM emission inventories are compared with EMEP gas and aerosol surface based measurements, AERONET sun photometers retrievals and MODIS satellite data. For the aerosol precursor gasses NOx and SO2 in both months the model results calculated with the EMEP inventory agree better with the EMEP measurements than the simulation with the AEROCOM inventory. In June, with the AEROCOM inventory, SO2 and NOx concentrations are overestimated by a factor of 2.4 and 1.9, respectively. In contrast, the EMEP inventory only slightly overestimates the measured concentrations with a factor 1.3 for both SO2 and NOx. Besides the differences in total emissions between the two inventories, an important role is also played by the vertical distribution of SO2 and NOx emissions in understanding the differences between the EMEP and AEROCOM inventories. In December NOx and SO2 from both simulations agree within 50 % with observations. In June SO4= evaluated with the EMEP emission inventory agrees slightly better with surface observations than the AEROCOM simulation, whereas in December the use of both inventories results in an underestimate of SO4 with a factor 2. Nitrate aerosol measured in summer is not reliable, however in December nitrate aerosol calculations with the EMEP and AEROCOM agree with 30%, and 60 %, respectively with the filter measurements. Differences are caused by the total emissions and the temporal distribution of the aerosol precursor gasses NOx and NH3. Despite these differences, we show that the column integrated AOD is less sensitive to the underlying emission inventories. Calculated AOD values with both emission inventories underestimate the observed AERONET AOD values by 20 - 30%, whereas a case study using MODIS data shows a high spatial agreement. Our evaluation of the role of temporal distribution of anthropogenic emissions on aerosol calculations shows that the daily and weekly temporal distributions of the emissions are only important for NOx, NH3 and aerosol nitrate. For the aerosols species SO4=, NH4+, POM, BC, as well as for AOD, the weekly and daily temporal variation appear not to be important. However, the seasonal temporal variations used in the emission inventory are important for all species under consideration. Our study shows the value of including at least seasonal information on anthropogenic emissions, although from a comparison with a range of measurements it is often difficult to firmly identify the superiority of specific emission inventories, since other modelling uncertainties, e.g. related to transport, aerosol removal, water uptake, and model resolution, play a dominant role.JRC.H.4-Transport and air qualit