Modelling of Meteorological Conditions at an Urban Scale for the Puma Summer Campaign

This study examines the urban mixing height (MH) using a 3D non-hydrostatic mesoscale meteorological model, the Regional Atmospheric Modelling System (RAMS). Temperature and humidity profiles, and turbulent kinetic energy (TKE) (Batchvarova et al.,1999) output from the model allows one to estimate MH. To determine successfully the MH for the U.K. West Midlands, RAMS is modified to adapt the newly-defined urban surface types. Ten urban landuse types are identified using remote sensing images and validated by maps. Corresponding to each landuse type, roughness lengths are calculated using a scheme based on Bottema (1995). Appropriate urban meteorological parameterisation schemes for the quantities such as albedo and emissivity are also incorporated into RAMS, which is run at a 2km resolution. The output from the RAMS model is validated using data from a tethered balloon sonde as well as from about twenty surface weather stations established over the West Midlands. A series of sensitivity tests are also carried out to examine the effects of the surface parameters on the MH over an urban surface. The output from the modified RAMS model allows for more accurate wind fields for the urban area which can be used for photochemical modelling applications.