Fine Resolution Atmospheric Multi-pollutant Exchange Model Research Articles

The uncertainty in modelled air concentrations of NO<SUB align="right">x due to choice of emission inventory

Emission data, together with meteorology, is the most important input to air quality models. In this work we compare two simulations, performed with the fine resolution atmospheric multi-pollutant exchange (FRAME) model. In the first model run, we use an emission inventory prepared for Poland by downscaling the national total emissions to a 5 km × 5 km resolution grid. For the second model run, we replace the NOx road transport emission with the TNO-MACC II emission inventory available for the entire Europe. The grid mesh of both emission inventories was unified for this work to a 5 km × 5 km resolution, as required by the FRAME model. The FRAME model is run for the year 2008 and compared with the NOx measurements. Both inventories are in close spatial agreement, with a grid to grid correlation coefficient of 0.75. The FRAME model run with TNO-MACC II emission inventory shows better agreement with NOx measurements gathered at 106 stations if the mean bias is considered. For the model run with TNO-MACC II inventory, bias is −0.7 μg m³, and the RMSE is 8.19 μg m³. The bias for the FRAME model run with the national road transport emission inventory is −3.10 μg m³ and the RMSE 7.97 μg m³.

The influence of model grid resolution on estimation of national scale nitrogen deposition and exceedance of critical loads

Abstract. The Fine Resolution Atmospheric Multi-pollutant Exchange model (FRAME) was applied to model the spatial distribution of reactive nitrogen deposition and air concentration over the United Kingdom at a 1 km spatial resolution. The modelled deposition and concentration data were gridded at resolutions of 1 km, 5 km and 50 km to test the sensitivity of calculations of the exceedance of critical loads for nitrogen deposition to the deposition data resolution. The modelled concentrations of NO2 were validated by comparison with measurements from the rural sites in the national monitoring network and were found to achieve better agreement with the high resolution 1 km data. High resolution plots were found to represent a more physically realistic distribution of reactive nitrogen air concentrations and deposition resulting from use of 1 km resolution precipitation and emissions data as compared to 5 km resolution data. Summary statistics for national scale exceedance of the critical load for nitrogen deposition were not highly sensitive to the grid resolution of the deposition data but did show greater area exceedance with coarser grid resolution due to spatial averaging of high nitrogen deposition hot spots. Local scale deposition at individual Sites of Special Scientific Interest and high precipitation upland sites was sensitive to choice of grid resolution of deposition data. Use of high resolution data tended to generate lower deposition values in sink areas for nitrogen dry deposition (Sites of Scientific Interest) and higher values in high precipitation upland areas. In areas with generally low exceedance (Scotland) and for certain vegetation types (montane), the exceedance statistics were more sensitive to model data resolution.

Modelling emission, concentration and deposition of sodium for Poland

The aim of this paper was to calculate natural and anthropogenic emission of Na + and to estimate, with the FRAME model, annual air concentration and deposition of Na + for the domain covering Poland. Calculations of natural emissions included marine emission and wind blown dust from land. Anthropogenic emission was calculated for both point and area sources. Emission maps were used in fine resolution atmospheric multi-pollutant exchange (FRAME) model, and annual average concentration and total deposition of Na + at the 5 km × 5 km spatial resolution were calculated. A clear gradient from the north and north west towards the centre of Poland is observed for spatial distribution of air concentration and wet deposition of Na + , as sea salt aerosol contributes the majority of Na + deposited in Poland. Comparison of FRAME wet deposition results with available measurements values indicates that the model is capable of reproducing annual deposition of sodium in Poland.

Simulation of nitrogen deposition in the North China Plain by the FRAME model

Abstract. Simulation of atmospheric nitrogen (N) deposition in the North China Plain (NCP) at high resolution, 5 × 5 km2, was conducted for the first time by the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model. The total N deposition budget was 1481 Gg in this region, with 77 % from reduced N and 23 % from oxidized N, and the annual deposition rate (47 kg N ha−1) was much higher than previously reported values for other parts of the world such as the UK (13 kg N ha−1), Poland (7.3 kg N ha−1) and EU27 (8.6 kg N ha−1). The exported N component (1981 Gg) was much higher than the imported N component (584 Gg), suggesting that the NCP is an important net emission source of N pollutants. Contributions of N deposition budgets from the seven provinces in this region were proportional to their area ratios. The calculated spatial distributions of N deposition displayed high rates of reduced N deposition in the south and of oxidized N deposition in the eastern part. The N deposition exceeded an upper limit of 30 kg N ha−1 for natural ecosystems over more than 90 % of the region, resulting in terrestrial ecosystem deterioration, impaired air quality and coastal eutrophication not only in the NCP itself but also in surrounding areas including the Bohai Sea and the Yellow Sea.

Modelling of marine base cation emissions, concentrations and deposition in the UK

Abstract. Base cations exert a large impact on various geochemical and geophysical processes both in the atmosphere and at the Earth surface. One of the essential roles of these compounds is impact on surface pH causing an increase in alkalinity and neutralizing the effects of acidity generated by sulphur and nitrogen deposition. During recent years anthropogenic emissions of base cations in the UK have decreased substantially, by about 70%, 78%, 75% and 48% for Na+, Mg2+, Ca2+ and K+, respectively, over the period 1990–2006. For the island regions, such as the UK, the main source of base cation particles is the aerosol produced from the sea surface. Here, the sea salt aerosol (SSA) emissions are calculated with parameterisations proposed by Mårtensson et al. (2003) for ultra fine particles, Monahan et al. (1986) for fine particles and Smith and Harisson (1998) for coarse particles continuously with a 0.1 μm size step using WRF-modelled wind speed data at a 5 km × 5 km grid square resolution with a 3 h time step for two selected years 2003 and 2006. SSA production has been converted into base cation emissions, with the assumption that the chemical composition of the particle emitted from the sea surface is equal to the chemical composition of sea water, and used as input data in the Fine Resolution Atmospheric Multi-pollutant Exchange Model (FRAME). FRAME model annual mean concentrations and total wet deposition at a 5 km × 5 km grid resolution, are compared with concentrations in air and wet deposition from the National Monitoring Network and measurements based estimates of UK deposition budget. The correlation coefficient for wet deposition achieves high values (R = 0.8) for Na+ and Mg2+, whereas for Ca2+ the correlation is poor (R < 0.3). Base cation concentrations are also represented well, with some overestimations on the west coast and underestimations in the centre of the land.

Modelling deposition and air concentration of reduced nitrogen in Poland and sensitivity to variability in annual meteorology

The relative contribution of reduced nitrogen to acid and eutrophic deposition in Europe has increased recently as a result of European policies which have been successful in reducing SO2 and NOx emissions but have had smaller impacts on ammonia (NH3) emissions. In this paper the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model was used to calculate the spatial patterns of annual average ammonia and ammonium (NH4+) air concentrations and reduced nitrogen (NHx) dry and wet deposition with a 5 km × 5 km grid for years 2002–2005. The modelled air concentrations of NH3 and dry deposition of NHx show similar spatial patterns for all years considered. The largest year to year changes were found for wet deposition, which vary considerably with precipitation amount. The FRAME modelled air concentrations and wet deposition are in reasonable agreement with available measurements (Pearson’s correlation coefficients above 0.6 for years 2002–2005), and with spatial patterns of concentrations and deposition of NHx reported with the EMEP results, but show larger spatial gradients. The error statistics show that the FRAME model results are in better agreement with measurements if compared with EMEP estimates. The differences in deposition budgets calculated with FRAME and EMEP do not exceed 17% for wet and 6% for dry deposition, with FRAME estimates higher than for EMEP wet deposition for modelled period and lower or equal for dry deposition. The FRAME estimates of wet deposition budget are lower than the measurement-based values reported by the Chief Inspectorate of Environmental Protection of Poland, with the differences by approximately 3%.Up to 93% of dry and 53% of wet deposition of NHx in Poland originates from national sources. Over the western part of Poland and mountainous areas in the south, transboundary transport can contribute over 80% of total (dry + wet) NHx deposition. The spatial pattern of the relative contribution of national sources to total deposition of NHx may change significantly due to the general circulation of air.

The influence of long term trends in pollutant emissions on deposition of sulphur and nitrogen and exceedance of critical loads in the United Kingdom

Abstract In the United Kingdom, as with other European countries, land-based emissions of NO x and SO 2 have fallen significantly over the last few decades. SO 2 emissions fell from a peak of 3185 Gg S in 1970 to 344 Gg S in 2005 and are forecast by business-as-usual emissions scenarios to fall to 172 Gg by 2020. NO x emissions were at a maximum of 951 Gg N in 1970 and fell to 378 by 2005 with a further decrease to 243 Gg N forecast by 2020. These large changes in emissions have not been matched by emissions changes for NH 3 which decreased from 315 Gg N in 1990 to 259 in 2005 and are forecast to fall to 222 by 2020. The Fine Resolution Atmospheric Multi-pollutant Exchange model (FRAME) has been applied to model the spatial distribution of sulphur and nitrogen deposition over the United Kingdom during a 15-year time period (1990–2005) and compared with measured deposition of sulphate, nitrate and ammonium from the national monitoring network. Wet deposition of nitrogen and sulphur was found to decrease more slowly than the emissions reductions rate. This is attributed to a number of factors including increases in emissions from international shipping and changing rates of atmospheric oxidation. The modelled time series was extended to a 50-year period from 1970 to 2020. The modelled deposition of SO x , NO y and NH x to the UK was found to fall by 87%, 52% and 25% during this period. The percentage area of sensitive habitats in the United Kingdom for which critical loads are exceeded is estimated to fall from 85% in 1970 to 37% in 2020 for acidic deposition and from 73% to 49% for nutrient nitrogen deposition. The significant reduction in land emissions of SO 2 and NO x focuses further attention in controlling emissions from international shipping. Future policies to control emissions of ammonia from agriculture will be required to effect further significant reductions in nitrogen deposition.