de Meij, A; Pozzer, A; Pringle, KJ; Tost, H; Lelieveld, J (2012). EMAC model evaluation and analysis of atmospheric aerosol properties and distribution with a focus on the Mediterranean region. ATMOSPHERIC RESEARCH, 114, 38-69.

Abstract
The skill of the EMAC atmospheric chemistry-climate model to predict the aerosol optical depth (AOD) is evaluated by comparing with remote sensing data products from AERONET, MODIS, MISR and CALIOP with a focus on the Mediterranean region. In addition, calculated aerosol concentrations are compared with measurements from the CASTNET, IMPROVE, EMEP, EANET and CAWNET networks. Calculated sulphate concentrations are in good agreement with the measurements, whilst the agreement is less satisfactory for ammonium and nitrate, possibly because of measurement artefacts. The model reproduces the main spatial atmospheric distribution of the sulphate and ammonium aerosols. For nitrate some differences are found when compared to observations. The analysis of black and organic carbon (BC and OC) over Europe shows that the model typically overestimates observed BC concentrations by a factor of 1.6 and underestimates OC by a factor of 2.6. For the USA BC and OC are in general overestimated and for China BC and OC are in general underestimated by the model. The seasonal distribution of elevated AODs is well represented by the model when compared to MODIS and MISR, though AODs are somewhat low-biased. Calculated annual mean AODs are in general lower than of AERONET and the temporal correlation coefficients vary between 0.11 and 0.68. High temporal correlation coefficients are found for biomass burning regions (South America and West Africa), indicating that the seasonal cycle of this source category is well represented in the model, based on the GFED inventory. High temporal correlation coefficients are obtained for the Mediterranean region during summer, which indicates that the model captures the dust intrusions. Our model calculations show that inorganic particles and associated water are the most abundant aerosol components over Europe, North America and Asia, whilst over the Mediterranean during summer dust dominates the total AOD. An analysis of the meridional vertical distribution of model calculated dust indicates good agreement with CALIOP observations for locations near the Mediterranean and over northern Africa. The modelled underestimation of the AODs over Europe and the USA is larger at low than at high relative humidity, indicating that the concentrations of hygroscopic aerosols are too low. (c) 2012 Elsevier B.V. All rights reserved.

DOI:
0169-8095

ISSN:
10.1016/j.atmosres.2012.05.014