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 Implementation of MAFOR Aerosol Dynamics in the EMEP MSC/W Model
The aerosol dynamics of the MAFOR model will be a future option of the EMEP-MSC/W model ( The EMEP-MSC/W model is a 3-dimensional atmospheric transport chemistry model designed to calculate air concentrations and deposition fields for major acidifying and eutrophying pollutants, photo-oxidants and particulate matter. The inclusion of MAFOR enables the calculation of size-resolved particle number (PN) concentrations and particulate sulfate.

The modelled European distribution (average August 2008) of total PN concentration of 3 to 10 nm diameter particles (upper left), >10 to 100 nm diameter particles (upper right), >100 to 1000 nm particles (lower left), and >1 to 10 um particles (lower right). [Grafics are courtesy Dr. Svetlana Tsyro,]

The implementation of aerosol dynamics in the EMEP-MSC/W model brings into effect a coupling between the gas phase chemistry, producing sulfuric acid by the oxidation of sulfur dioxide, and the particle formation via nucleation and condensation of sulfuric acid. Growth of particles occurs by condensation and coagulation of particles. Water content of the aerosol is calculated as thermodynamic equilibrium for each size section of the aerosol distribution.

The modelled European distribution (average August 2008) of gas phase sulfuric acid (H2SO4) concentration (left) and total mass concentration of particulate sulfate (right). [Grafics are courtesy Dr. Svetlana Tsyro,]

Biogenic Secondary Organic Aerosol (BSOA) is formed in the photo-oxidation of isoprene and a-pinene emitted from forests and other vegetation. Condensation of a low-volatile biogenic vapour enhances growth of new particles. In springtime BSOA starts to form over the boreal forests (upper pannel). Nucleation mode particle numbers are increasing in the boreal region and also in parts of the Mediterranean where their formation is mainly due to sulfphuric acid. In summer, when the forest canopy emits large amounts of precursors, modelled concentrations of BSOA and new particles are increased over large parts of Europe (lower pannel). [Grafics are courtesy Dr. Svetlana Tsyro,]

The inclusion of the MAFOR source code into the open source Unified EMEP model means a large step towards the final opening of the aerosol dynamic source code to the scientific community. During 2015, MAFOR aerosol dynamics will become part of the EMEP model svn, under the GNU General Public License (GPL).