Evaluation of the performance of different atmospheric chemical transport models and inter-comparison of nitrogen and sulphur deposition estimates for the UK

Abstract

Date of Acceptance: 03/08/2015. Open Access funded by Natural Environment Research Council - Attribution 4.0 International (CC BY 4.0)An evaluation has been made of a number of contrasting atmospheric chemical transport models, of varying complexity, applied to estimate sulphur and nitrogen deposition in the UK. The models were evaluated by comparison with annually averaged measurements of gas, aerosol and precipitation concentrations from the national monitoring networks. The models were evaluated in relation to performance criteria. They were generally able to satisfy a criterion of ???fitness for purpose??? that at least 50% of modelled concentrations should be within a factor of two of measured values. The second criterion, that the magnitude of the normalised mean bias should be less than 20%, was not always satisfied. Considering known uncertainties in measurement techniques, this criterion may be too strict. Overall, simpler models were able to give a good representation of measured gas concentrations whilst the use of dynamic meteorology, and complex photo-chemical reactions resulted in a generally better representation of measured aerosol and precipitation concentrations by more complex models. The models were compared graphically by plotting maps and cross-country transects of wet and dry deposition as well as calculating budgets of total wet and dry deposition to the UK for sulphur, oxidised nitrogen and reduced nitrogen. The total deposition to the UK varied by +/- 22-36% amongst the different models depending on the deposition component. At a local scale estimates of both dry and wet deposition for individual 5km x 5 km model grid squares were found to vary between the different models by up to a factor of 4

Drivers for spatial, temporal and long-term trends in atmospheric ammonia and ammonium in the UK

“…4b). Thus there is a general decreasing gradient from the southeast to the northwest of the UK, due to both NH 3 sources in England and import of particulate matter from Europe (Vieno et al, 2014;Dore et al, 2015). The limited variation across the UK for the annual average NH + 4 concentrations can be attributed to the atmospheric formation process (providing a diffuse source) and its longer atmospheric lifetime.…”

“…Similarly, the monitoring sites were strategically selected to cover source areas of expected high concentrations and variability on the basis of the FRAME model NH 3 concentration estimates (Fig. 1a, b), and this approach was expected to provide additional evidence to test the performance of atmospheric dispersion models (Fournier et al, 2005;Dore et al, 2015). When compared with other atmospheric chemistry transport models, FRAME was found to correlate well with measured NH 3 concentrations (Dore et al 2015).…”

“…1a, b), and this approach was expected to provide additional evidence to test the performance of atmospheric dispersion models (Fournier et al, 2005;Dore et al, 2015). When compared with other atmospheric chemistry transport models, FRAME was found to correlate well with measured NH 3 concentrations (Dore et al 2015). The NAMN sites were also similarly checked for representativeness of particulate NH + 4 by comparing FRAMEmodelled NH + 4 concentrations at NAMN sites with modelled concentrations for the whole of the UK, which demonstrates a good representation across the range of expected concentrations (Fig.…”

Global sensitivity and uncertainty analysis of an atmospheric chemistry transport model: the FRAME model (v. 9.15.0) as a case study

“…A detailed evaluation of model outputs with annually averaged measurements of pollutant concentrations in air and precipitation concentrations is discussed elsewhere (Dore et al, 2015). In this study, all model runs were performed using emissions and meteorology data for the year 2012 and FRAME model version 9.15.0.…”

Bioindication and modelling of atmospheric deposition in forests enable exposure and effect monitoring at high spatial density across scales

“…Additionally, the study investigated whether moss specimens indicate atmospheric deposition in a similar way as modelled deposition, tree foliage and natural surface soil at the European and country level, and whether they indicate site-specific variance due to canopy drip (3). Since the results of modelling of deposition may depend on the structure and functions of the models as well as on the input data in terms of meteorology and emissions (Dore et al 2015;Ilyin and Travnikov 2005), we used results from the EMEP and LOTOS-EUROS deposition model. These three objectives were examined with the data and methods compiled in Table 1 and explained in Section 2 sub-divided into "Data" (Section 2.1), "Minimum sample size" (Section 2.2), "Geostatistics and mapping" (Section 2.3) and "Correlation analyses" (Section 2.4).…”