eTheses Repository - University of Birmingham

cities (Baker et al. 2002). Already more then 80% of the UK population resides in urban
areas (DETR 2000). A significant effect of the urban area on regional meteorology and
climate has been identified in previous studies for a number of different urban areas (e.g.
Dupont et al. 1999; Troude et al. 2002; Trusilova et al. 2008), and has been quantified for
London in this PhD study. The urban area, in its current form based on data from the CEH
Land Cover Map 2000, is found to affect near surface temperature, the diurnal temperature
range (DTR), the UHI, and the near surface wind speed and direction. The effect is shown
to have a regional character, with both urban and surrounding rural areas demonstrating a
significant impact. Under a given meteorological condition, peak UHI intensities of up to
2.5 K are found during night time hours, with the timing and magnitude of the peak
showing good agreement with previous experimental studies for London (Graves et al.
2001).
A large number of studies have investigated the sensitivity of the mesoscale atmospheric
models to the presence of vegetation in an urban area, and this was found to have a
significant impact on simulated near surface temperatures and air quality (Taha 1996, 1997;
Civerolo et al. 2000) and the boundary layer structure (Pielke et al. 1998; Seaman 2000).
The results in this PhD study for past urbanisation confirm that the relative fractions of
urban land cover and of vegetation within the urban area have important implications for
the near surface temperature, DTR, wind speed and UHI intensity. It is suggested that the
effect of the relative percentage of urban/vegetation land cover fractions has a more
significant effect on these meteorological fields when compared to a more compact urban
form. The London Boroughs and Greater London Authority (GLA) have a policy for
protecting existing green space from development in order to help offset the UHI effect
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