eTheses Repository - University of Birmingham

2.3 Justification of modelling approach
In Section 2.2 the difficulties in measuring the urban impact on temperature by the comparison of
observations have been discussed. Due to these difficulties modelling may be a valuable tool for
investigating the effects of land use change, and urbanisation in particular, on weather and
climate at a regional scale (Lamptey et al. 2005). An advantage of the modelling approach is that
it is possible to eliminate the effect of climate variability and non stationarity.
For example, although their focus was primarily on vegetation, Stohlgren et al. (1998) performed
simulations for different land use scenarios representing the natural pre-European settlement state
of vegetation, current land use and an increase in irrigated land and concluded that the effects of
land use practices on regional climate could overshadow larger scale effects such as those due to
greenhouse gases.
Many modelling studies focusing on the expansion of the urban area have not fully represented
the effects of the urban area on the mesoscale flow. For example a modelling study by Ichinose
(2001) on the regional warming due to land use change during the past 135 years in Japan has
shown that the effect of urbanisation through time has produced a change in mesoscale flows,
through the weakening of the daytime penetration of the sea breezes, and a regional warming.
However this study did not consider the effects of the urban canopy structure and the shadowing
and trapping of radiation therein are not accounted for in the mesoscale model used in this work,
which could be the cause of the disagreement between the simulated daily minimum
temperatures and those estimated from observed data (Ichinose 2001). Likewise, Klaić et al.
(2002) investigated the impact of two scenarios of hypothetical urbanisation in the Zagreb area
on the local winds but in this study the urban surface was represented as a land class
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