Atmos. Chem. Phys. Discuss., 9, 9597-9645, 2009
© Author(s) 2009. This work is distributed
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Parameterization of vertical diffusion and the atmospheric boundary layer height determination in the EMEP model
A. Jeričević1, L. Kraljević1, B. Grisogono2, and H. Fagerli3
1Meteorological and Hydrological Service of Croatia, Zagreb, Croatia
2Andrija Mohorovičić Geophysical Institute, Department of Geophysics, Faculty of Science, University of Zagreb, Croatia
3Norwegian Meteorological Institute, Oslo, Norway

Abstract. A new vertical diffusion scheme, called Grisogono, has been implemented in the Unified EMEP (European Monitoring and Evaluation Programme) model. It is shown based on Large Eddy Simulation (LES) that the Grisogono method performs better than the operational O'Brien's polynomial, especially in the stable conditions. In this work, the operational and proposed new parameterization for eddy diffusivity K(z) have been validated against observed daily surface nitrogen dioxide (NO2), sulphur dioxide (SO2) and sulphate (SO4−2) concentrations at different EMEP stations during year 2001. Moderate improvement in the correlation coefficient and bias for NO2 and SO2 and slight improvement for sulphate is found for most of the analyzed stations with the Grisogono K(z) scheme, which is recommended for further application due to its scientific and technical advantages. Special emphasis is given to the representation of the atmospheric boundary layer (ABL) in order to capture vertical transport and dispersion of atmospheric air pollution. Two different ABL schemes are evaluated against radiosounding data in January and July 2001, and against data from the Cabauw tower, the Netherlands, in the same year. Based on validation of the ABL parameterizations, it is found that the EMEP model is able to reproduce spatial and temporal mixing height variability. Improvements are identified especially in stable conditions with the new ABL scheme based on the bulk Richardson number (RiB).

Citation: Jeričević, A., Kraljević, L., Grisogono, B., and Fagerli, H.: Parameterization of vertical diffusion and the atmospheric boundary layer height determination in the EMEP model, Atmos. Chem. Phys. Discuss., 9, 9597-9645, doi:10.5194/acpd-9-9597-2009, 2009.
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