Formation and dispersion of secondary inorganic aerosols by high ammonia emissions Eberhard Renner, Ralf Wolke Leibniz Institute for Tropospheric Research, Leipzig GLOREAM Paris, Oct. 2006

OUTLINE  MOTIVATION  MODELLING APPROACH  SOME RESULTS  SUMMERY

MOTIVATION  Fine and ultra-fine particles are increasingly suspected to cause damages in human health and natural environment.  Besides the reduction of primary emissions by traffic, industry, agriculture and other sources, currently the focus of environmental sciences and politics is directed also at the formation of secondary particles.

 In this study the contribution of ammonia emissions especially from agriculture and livestock husbandry to the formation of inorganic secondary particles (PM 2.5 and PM 10 ) in a regional scale for longer time periods will be examined.  The modelling work is part of the project AMMONISAX, a measuring project, to compare different measuring methods for ammonia, funded by the German Federal State Niedersachsen.

CTM Parallel MUSCAT Emissions Landuse Data Meteorology: Parallel LM Gasphase Chemistry RACM Aerosoldynamics „EMEP“ Post-Processing onlinedata-file MODELLING APPROACH

ANTHROPGENIC EMISSIONS  10 SNAP codes of EMEP/CORINAIR for characterising the different anthropogenic source types (e.g., combustion in energy industry, road transport, agriculture) are used.  The considered chemical species are the main pollutants SO 2, NO x, CO, NH 3, PM 2.5, PM 10, methane, and non-methane volatile organic compounds (NMVOC).  5% of SO 2 are emitted directly as sulfate.  The TNO/UBA emission data were used, with a resolution of 15x15km for the European Region.

BIOGENIC EMISSIONS  The NO emissions are calculated in dependence on the vegetation type and surface temperature (Williams et al.).  The VOC emissions additionally depend on sunlight (Günther et al.).

METEOROLOGICAL MODEL  LM (Local Model) of German Weather Service  non-hydrostatic  operational mode for weather forcast  regional scale  boundary and initial data from GME  highly parallel

CHEMISTRY-TRANSPORT-MODEL  MUSCAT (Multi-Scale Atmospheric Transport Model)  The transport processes include advection, turbulent diffusion, dry and wet deposition and sedimentation  Gas phase mechanism RACM  Aerosol model:mass-based scheme (similar to the EMEP model)

AEROSOL MODEL  The study is focused mainly of secondary inorganic particles with sizes below 10 μm (PM 10 ).  The dominant contribution to mass increasing is caused by the heterogeneous condensation of gaseous compounds on pre-existing aerosols.  Ammonia and sulfuric/nitric acid, generated by several paths from the precursory species SO 2 and NO x, are involved.

5 %

 Refinement factor is 2;  Refinement level between neighbouring blocks is restricted to 1;  No overlapping blocks;  Mass-conservation is saved !! Decomposition of Horizontal Domain Static grid in a “multiblock approach“

NUMERICAL METHODS  Space discretization  Staggered grid. Finite-volume techniques  Advection: Third-order upwind scheme (Hundsdorfer et al.,1995)  Time-integration: IMEX scheme  Explicit second-order Runge-Kutta for horizontal advection  Second order BDF method for the rest: Jacobian is calculated explicitly, linear systems by Gauss-Seidel iterations or AMF  Automatic step size control  Parallelization domain decomposition, load-balancing

Coupling Scheme  Time interpolation of the meteorological fields: 1. Linear interpolated in [tn,tn+1]: Temperature, Density,…. 2. Time-averaged values on [tn,tn+1]: Projected wind field, necessary for mass conservation !!  Separate time step size control for LM and MUSCAT

Coupling Scheme new approach for SAMUM Feedback  Feedback of dust to radiation!

RESULTS  Results are shown for May At the beginning of the month it was a high pressure period with moderate winds from East. The second half was a period with stronger winds from West.

SUMMERY  The formation of mass of secondary inorganic particles (PM 10 ) was examined in a region of higher ammonina emissons.  More than 50% of the simulated PM 10 -mass were secondary formatted ammonia sulfate and ammonia nitrate.  The fraction of ammonia nitrate was extrem dependent from the meteorological conditions.  It seems to exists a significant deficiency in primary emitted particles, especially by easterly winds!