Spatial neighborhood analysis linking urban morphology and green infrastructure to atmospheric conditions in Karlsruhe, Germany

Urban areas are affected by the urban heat island effect, resulting in increased heat strain compared to rural areas. In this article, we aimed to study how urban morphology (e.g., building structure, sealing, and availability of green space) influenced meteorological variables and human thermal comfort on the microscale. Mobile measurements were performed during autochthonal weather conditions in Karlsruhe. Post-processing includes the transfer from a temporal (1 observation per s) to a spatial resolution (1 observation per 5 m), the normalization of the air temperature to the data range [0,1], and the spatial aggregation to account for inaccuracies in the Global Navigation Satellite System. The processed data were linked to the neighborhood's characteristics for a spatial analysis, specified by remotely-sensed and administrative geodata. The analysis encompassed the relationship of land use, sealing factor, and normalized difference vegetation index to the normalized air temperature. It revealed the dependency of the cooling effect of urban vegetation on the size as well as on the greenness of green spaces, while sealing showed an inverse effect. Our results will help urban planners take action during heat waves in the future. Furthermore, normalization enables the comparability of urban climate studies of varying latitudes and climate regions.