The European aerosol budget in 2006

Abstract

Abstract. This paper presents the aerosol budget over Europe in 2006 calculated with the global transport model TM5 coupled to the size-resolved aerosol module M7. Comparison with ground observations indicates that the model reproduces the observed concentrations quite well with an expected slight underestimation of PM 10 due to missing emissions (e.g. resuspension). We model that a little less than half of the anthropogenic aerosols emitted in Europe are exported and the rest is removed by deposition. The anthropogenic aerosols are removed mostly by rain (95%) and only 5% is removed by dry deposition. For the larger natural aerosols, especially sea salt, a larger fraction is removed by dry processes (sea salt: 70%, mineral dust: 35%). We model transport of aerosols in the jet stream in the higher atmosphere and an import of Sahara dust from the south at high altitudes. Comparison with optical measurements shows that the model reproduces theÅngström parameter very well, which indicates a correct simulation of the aerosol size distribution. However, we underestimate the aerosol optical depth. Because the surface concentrations are close to the observations, the shortage of aerosol in the model is probably at higher altitudes. We show that the discrepancies are mainly caused by an overestimation of wet-removal rates. To match the observations, the wet-removal rates have to be scaled down by a factor of about 5. In that case the modelled ground-level concentrations of sulphate and sea salt increase by 50% (which deteriorates the match), while other components stay roughlyCorrespondence to: J. M. J. Aan de Brugh (joost.aandebrugh@wur.nl) the same. Finally, it is shown that in particular events, improved fire emission estimates may significantly improve the ability of the model to simulate the aerosol optical depth. We stress that discrepancies in aerosol models can be adequately analysed if all models would provide (regional) aerosol budgets, as presented in the current study.

Aerosol optical depth over the Arctic: a comparison of ECHAM-HAM and TM5 with ground-based, satellite and reanalysis data

“…It represents sulphate, black carbon, organic carbon, sea salt and mineral dust in seven internally mixed soluble or insoluble log-normal size modes. Gas-particle partitioning of ammonium nitrate is calculated using the EQSAM thermodynamic equilibrium model, as described in Aan den Brugh et al (2011). The gas-phase chemistry scheme is based on the Carbon Bond Mechanism 4 (CMB4) and is given in Huijnen et al (2010).…”

The impact of precipitation evaporation on the atmospheric aerosol distribution in EC-Earth v3.2.0

“…Compared to observations, the aerosol optical depth (AOD) field simulated in TM5 has generally been too low (see, e.g. Aan de Brugh et al, 2011;van Noije et al, 2014). This has been a point of attention for several cycles of the model and although substantial improvements have been made, the underestimation has not been completely resolved as of yet.…”

“…Together with the mass and number, each mode has a fixed width that describes the size distribution of the aerosols. A more detailed overview of the implementation of M7 in TM5 is given by Aan de Brugh et al (2011) andvan Noije et al (2014). Other species included in the model are nitrate, ammonium and methane sulfonic acid (MSA), and are described by their total mass only.…”

“…For calculations of, e.g. aerosol mode radii and optical properties, the mass of ammonium nitrate and MSA are assumed to be condensed on the soluble accumulation-mode particles of M7 (see Aan de Brugh et al, 2011).…”

A pathway analysis of global aerosol processes

“…Following that, models started to simulate a combination of aerosol species that were externally mixed, (Takemura et al, 2000;Chin et al, 2002). These days several models exist that allow time-varying sizes and species compositions of aerosol particles (Adams and Seinfeld, 2002;Easter et al, 2004;Liao et al, 2004;Liu et al, 2005;Stier et al, 2005;Spracklen et al, 2005;Bauer et al, 2008;Seland et al, 2008;Yu and Luo, 2009;Aan de Brugh et al, 2011). This increase in sophistication allowed the inclusion of more processes: from emission, transport and deposition for the earlier models to new particle formation, coagulation and gaseous condensation in the latter.…”