Simulating climate change in UK cities using a regional climate model, HadRM3

A regional climate model (RCM) at 25 km resolution, coupled to a simple urban land-surface scheme has been used to assess the sensitivity of UK urban climates to large-scale greenhouse gas (GHG) induced climate change, local forcing from urban land use, and anthropogenic heat flux (AHF) resulting from energy use in urban areas. GHG-induced climate change is similar over both urban and rural land surfaces in the model, suggesting that under a changing climate the relative magnitude of urban heat islands in the UK would remain the same. However, indirect effects from urbanisation or changes in energy consumption within UK cities would contribute to further localized anthropogenic climate change that can be quantified by this model. The presence of the urban heat island also has a significant impact on the frequency of extreme high temperatures both in present and future climates, and will exacerbate the impact of climate change on the urban population. The simple urban land-surface exchange scheme is a cost effective additional component of the RCM. It is shown to provide a realistic city-scale urban heat island responding to the dynamical weather of the model at every model time-step, with a magnitude and variability comparable to observed values. The climate model provides long integrations to derive large samples of heat islands under a full range of simulated dynamical conditions, and in this study sampling more than 100 years of climate change. Copyright (c) 2011 Royal Meteorological Society and British Crown copyright, the Met Office