A combined model for improving estimation of atmospheric boundary layer height

Atmospheric boundary layer height is one of the most important parameters in atmospheric dispersion modelling because it has a large effect on predicted air quality. Comparisons between Atmospheric Dispersion Modelling System, version 4 (ADMS 4) and lidar data were carried out on boundary layer height data from central London. The comparison showed that the boundary layer height predicted by the ADMS 4 was, on average, lower than lidar for the subset of data taken. ADMS 4 has a very simple surface scheme which is not representative of complex urban environments and the results from this research imply that there is not sufficient surface roughness within the model to produce a large enough boundary layer height. The aim of this study is to create an improved model to better forecast the growth of the daytime urban boundary layer and predict boundary layer height, h, in an air quality dispersion model using lidar measurements. The combined model was developed by using a surface model and an atmospheric boundary layer height model. Measurements of atmospheric boundary layer height by lidar used vertical velocity variance and the overall conclusion was that the combined model improved the performance of ADMS in urban areas.