Modeling the impact of sub-grid scale emission variability on upper-air concentration S. Galmarini1, J.-F. Vinuesa1, and A. Martilli2 1European Commission – DG Joint Research Centre, Institute for Environment and Sustainability, 21020 Ispra, Italy 2CIEMAT, Madrid, Spain
Abstract. The long standing issue of sub-grid emission heterogeneity and its influence
to upper air concentration is addressed here and a subgrid model proposed.
The founding concept of the approach is the assumption that average emission
act as source terms of average concentration, emission fluctuations are source for the concentration
variance. The model is based on the derivation of the sub-grid contribution of
emission and the use of the concentration variance equation to transport
it in the atmospheric boundary layer. The model has been implemented in an
existing mesoscale model and the results compared with Large-Eddy Simulation data for ad-hoc simulation
devised to test specifically the parametrization. The results show an excellent
agreement of the models. For the first time a time evolving error bar reproducing
the sub-grid scale heterogeneity of the emissions and the way in which it affects
the concentration has been shown. The concentration variance is presented as an
extra attribute to better define the mean concentrations in a Reynolds-average model.
The model has applications from meso to global scale and that go beyond air quality.
Citation: Galmarini, S., Vinuesa, J.-F., and Martilli, A.: Modeling the impact of sub-grid scale emission variability on upper-air concentration, Atmos. Chem. Phys., 8, 141-158, doi:10.5194/acp-8-141-2008, 2008.