Stochastic fields method for sub-grid scale emission heterogeneity in mesoscale atmospheric dispersion models 1Norwegian Institute for Air Research (NILU), 2027 Kjeller, Norway
2European Commission – DG Joint Research Centre, Institute for Environment and Sustainability, 21020 Ispra, Italy
Received: 13 Mar 2009 – Published in Atmos. Chem. Phys. Discuss.: 14 Jul 2009 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 are 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 adjustment of the constants used
in the mesoscale model. The stochastic fields method is a stochastic
solution of the transport equations for the concentration PDF of dispersing
scalars, therefore it possesses the ability to handle chemistry of any
complexity without the need to introduce additional closures for the high
order statistics of chemical species. This study shows for the first time
the feasibility of applying this method to mesoscale chemical transport
Revised: 18 Sep 2009 – Accepted: 25 Oct 2009 – Published: 13 Jan 2010
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., 10, 267-277, doi:10.5194/acp-10-267-2010, 2010.