Abstract
Abstract. The new global anthropogenic emission inventory (EDGAR-CIRCE) of gas and aerosol pollutants has been incorporated in the chemistry general circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry). A relatively high horizontal resolution simulation is performed for the years 2005–2008 to evaluate the capability of the model and the emissions to reproduce observed aerosol concentrations and aerosol optical depth (AOD) values. Model output is compared with observations from different measurement networks (CASTNET, EMEP and EANET) and AODs from remote sensing instruments (MODIS and MISR). A good spatial agreement of the distribution of sulfate and ammonium aerosol is found when compared to observations, while calculated nitrate aerosol concentrations show some discrepancies. The simulated temporal development of the inorganic aerosols is in line with measurements of sulfate and nitrate aerosol, while for ammonium aerosol some deviations from observations occur over the USA, due to the wrong temporal distribution of ammonia gas emissions. The calculated AODs agree well with the satellite observations in most regions, while negative biases are found for the equatorial area and in the dust outflow regions (i.e. Central Atlantic and Northern Indian Ocean), due to an underestimation of biomass burning and aeolian dust emissions, respectively. Aerosols and precursors budgets for five different regions (North America, Europe, East Asia, Central Africa and South America) are calculated. Over East-Asia most of the emitted aerosols (precursors) are also deposited within the region, while in North America and Europe transport plays a larger role. Further, it is shown that a simulation with monthly varying anthropogenic emissions typically improves the temporal correlation by 5–10% compared to one with constant annual emissions.
Highlights
Tropospheric aerosols have significant effects on human health (e.g. Huntingford et al, 2007), the water cycle (e.g. Ramanathan et al, 2001) and climate (e.g. Isaksen et al, 2009)
The explicit aerosol optical depth (AOD) calculation during the simulation allows a more detailed analysis than that performed by Pringle et al (2010a), who used an offline simplified treatment of AOD based on the parametrization of Kiehl and Briegleb (1993)
Excellent agreement is achieved between the model and observations of the CASTNET network, with spatial correlation coefficients higher than ∼ 0.8 and with 87 % of the modelled values within a factor of two of the observations, while some discrepancies in the spatial distribution are found over Europe and East Asia
Summary
Tropospheric aerosols have significant effects on human health (e.g. Huntingford et al, 2007), the water cycle (e.g. Ramanathan et al, 2001) and climate (e.g. Isaksen et al, 2009). We take advantage of the stateof-the-art emissions inventory EDGAR-Climate Change and Impact Research (CIRCE), which provides emissions on a high spatial (0.1 × 0.1◦) and temporal (monthly) resolution, together with a recently developed aerosol scheme implemented within the EMAC model (Pringle et al, 2010a). The first objective is to evaluate the model performance in simulating aerosol and AODs calculations using the EDGAR-CIRCE emission inventory by comparing the results with ground based and space borne observations. The second objective is to analyse the aerosol (precursor) budget for five regions (Europe, North America, East Asia, South America and Central Africa) and quantify the aerosol import and export terms, compared with previous studies. AOD is a very useful metric for analyzing model performance in regions where ground-based observations are sparse.
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