Urban Surface Energy Balance Models: Model Characteristics and Methodology for a Comparison Study - Meteorological and Air Quality Models for Urban Areas - page 106

whether the optimized parameters actually represent the processes they are
meant to, by assessing whether the parameters are within physically reasonable
bounds.
2) How complex does a model need to be in order to produce a realistic simulation
of urban fluxes and temperatures? More complex models tend to be more dif-
ficult to implement and require greater computational resources. By comparing
the performance of models grouped in terms of complexity, it will be possi-
ble to determine the model complexity required to accurately represent known
(observed) urban climatic features.
3) Which input parameter information is required by an urban model to perform
realistically? An array of parameters, particularly related to the urban surface, is
used in model simulations; specifically information on surface materials, build-
ing heights and shapes, distribution of heat sources, etc. Clearly, it is impossible
to incorporate into a model, or even to collect data, on all aspects of the urban
surface. Therefore guidance is needed to balance the complexity (and availabil-
ity) of the input parameters with the veracity of the models output. To assess this,
the models will be run in stages, with increasingly accurate parameter informa-
tion provided at each stage. By assessing the quality of the simulations for each
group at each stage, it will be possible to determine: the minimum number of
parameters required for a realistic simulation; what these parameters are, and
how accurately they need to be known.
4) What are the main research priorities for future observational campaigns within
urban areas? By answering the third question, it will also be possible to deter-
mine whether the essential parameters are being measured in observational
studies of cities, and whether techniques for determining these parameters actu-
ally exist. This will enable advice to be given to the measurement community
in terms of prioritising future observational research campaigns and to deter-
mine the routine measurements to be assimilated into forecast or air quality
models.
11.4 Conclusions
Given the broad range of applications in which urban surface energy balance
schemes are being used (e.g. simulations of the UHI, evaluation of different build-
ing/development strategies, air quality modelling, regional weather forecasting) and
the potential range of applications, a more systematic evaluation of existing mod-
els and areas of weakness is needed. This project will contribute to developing the
science for a sustainable future, as urban land use increases globally and as increas-
ing populations become exposed to microclimates with undoubted anthropogenic
influences.
Acknowledgments We wish to thank the UK Met Office, Vasilis Pappas (KCL), Rob Mullen
(KCL), Robert Ewen (KCL), Professor Andy Pitman (Macquarie University) and Dr Catherine
Souch (RGS-IBG) for their contributions to this project to date.