eTheses Repository - University of Birmingham

Figure 4.22 shows the vertical profiles potential temperature, wind speed and TKE at the
centre of the urban area at 04:00 for three simulations with different wind speed. As the
wind speed increases there is a marked difference in the potential temperature profile and in
the potential temperature at the first grid level. It is apparent that the urban surface
temperature is reduced by an increasing geostrophic wind speed. As can be expected the
wind speed above the urban area increases with the geostrophic wind speed. In the case
with the strongest geostrophic wind speed, the height at which the wind speed becomes
nearly constant is greater compared to the other two simulations. The shapes of the TKE
profiles are similar, with a maximum at the first grid level in all three simulations. The
maximum TKE value increases with the geostrophic wind speed, as does the PBL height.
This is due to a higher mechanical production of TKE produced by the buildings and shear
generation (Martilli 2002).
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