Evaluation of the surface parameterization JULES across a range of urban environments with varying vegetation plan area fractions

The Joint UK Land Environment Simulator (JULES) uses a slab approach to represent urban surfaces, where a canopy that has the thermal properties of urban elements is radiativelly coupled to the underlying soil, and a tile scheme for accounting for different surface types. In different versions of the model the urban surface can be modelled using either a single tile or it can be split into roof tops and canyons, to which appropriate parameter values are attributed. The model has participated in an international inter-comparison project where the implications of model complexity and surface parameters requirements were approached. Here, the performance of this simple model is evaluated for a range of different urban environments, from downtown areas or a European city centre, up to low-rise and highly vegetated suburbs. The model applicability for representing the surface energy balance in such a variety of conditions is evaluated and the implications of increasing vegetation coverage are analysed.