Modelling the urban heat island: sensitivity to land cover data

The MOCCA (MOnitoring the City's Climate and Atmosphere) network is measuring since July 2016 the urban climate of Ghent by using high-accuracy weather stations installed in different urban environments. Urban canopy temperature observations clearly show that surface properties (e.g. land cover fraction, building height...) determine the urban heat island (UHI) intensity. This relationship is also expected in simulations of the UHI since the radiation and energy balance in a land surface model, coupled to an atmospheric model, is based upon the characteristics of the surface. In this study we illustrate how the use of more accurate land cover data in the SURFEX surface scheme leads to an improved simulation of the nocturnal UHI of Ghent. As the modelled UHI is very sensitive to the land cover fractions, it can be concluded that it is important to use accurate, up-to-date surface information based on the newest techniques of remote sensing for UHI modelling.