Atmos. Chem. Phys. Discuss., 9, 15215-15245, 2009
www.atmos-chem-phys-discuss.net/9/15215/2009/
doi:10.5194/acpd-9-15215-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Stochastic fields method for sub-grid scale emission heterogeneity in mesoscale atmospheric dispersion models
M. Cassiani1, J. F. Vinuesa2, S. Galmarini2, and B. Denby1
1Norwegian Institute for Air Research (NILU), 2027 Kjeller, Norway
2European Commission – DG Joint Research Centre, Institute for Environment and Sustainability, 21020 Ispra, Italy

Abstract. The stochastic fields method for turbulent reacting flows has been applied to the issue of sub-grid scale emission heterogeneity in a mesoscale model. This method is a solution technique for the probability density function (PDF) transport equation and can be seen as a straightforward extension of currently used mesoscale dispersion models. It has been implemented in an existing mesoscale model and the results compared with Large-Eddy Simulation (LES) data devised to test specifically the effect of sub-grid scale emission heterogeneity on boundary layer concentration fluctuations. The sub-grid scale emission variability is assimilated in the model as a PDF of the emissions. The stochastic fields method shows excellent agreement with the LES data without the need of any additional model constants, nor the adjustment of the constants already used in the mesoscale model. The stochastic fields method solves transport equations of the concentration PDF for dispersing scalars and therefore it possesses the ability to handle chemistry of any complexity without closure assumptions. This study shows for the first time the feasibility of applying this method to mesoscale chemical transport models.

Citation: Cassiani, M., Vinuesa, J. F., Galmarini, S., and Denby, B.: Stochastic fields method for sub-grid scale emission heterogeneity in mesoscale atmospheric dispersion models, Atmos. Chem. Phys. Discuss., 9, 15215-15245, doi:10.5194/acpd-9-15215-2009, 2009.
 
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