eTheses Repository - University of Birmingham

Difference in potential temperature (K)
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Time
alb1-a01 alb2-a01
Figure 4.17: Diurnal variation of the difference in potential temperature (K) between the simulations
alb1 and the control simulation a01 (blue line) and between the simulations alb2 and a01 (pink line) at
x=0, y=0, z=10 m for the second day of simulation. The alb1 simulation represents an urban albedo of
0.30 and the alb2 simulation represents an urban albedo of 0.15.
It is clear that changing the albedo could be a relatively economical and achievable way of
influencing the urban daytime temperatures, and this could be investigated further at the
city scale for London, UK. The potential for increasing urban albedo has been investigated
for some others cities, for example Bretz et al. (1998) estimated the potential to modify the
albedo of Sacramento, California by 18%.
4.3.4 Sensitivity to the vegetation fraction
Like the surface albedo, the vegetative cover in the urban area also affects the surface
energy balance, and is another city characteristic which could be used as part of an
adaptation strategy to reduce urban temperatures (Sailor 1995, 1998; LCCP 2002). For an
urban area, the vegetation density and the land cover are crucial in determining the urban
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