Research note. Visualisation of summer heat intensity for different settlement types and varying surface fraction partitioning

Urban planners and stakeholders require knowledge about the effectiveness of city-scale climate adaptation measures in order to develop climate resilient cities and to push forward the political process for the implementation of climate adaptation strategies in cities. This study examines the impact of modifications in urban surface fractions of buildings, impervious and pervious surfaces on summer air temperatures using urban climate modelling of idealised cities. Sensitivity tests are performed for nine typical settlement types in Germany. The results for minimum and maximum temperatures are analysed and plotted in a ternary diagram. The novel approach of using ternary diagrams for the aggregation and visualisation of modelling results clearly identifies thermally unfavourable ranges of urban surface partitioning that should be avoided for urban settlements. Furthermore, the diagrams are used to derive quantitative recommendations for the most effective reduction of summer heat intensity.