Large-scale analysis of land surface temperature in Germany and its impact on population

Kurzfassung

Urbanization has resulted in significant land use and land cover changes with the replacement of natural land cover with impervious materials, resulting in a change in the thermal properties of urban landscapes. As such, urban environments have a relatively higher thermal capacity and a higher overall temperature than their surrounding rural areas: a phenomenon known as Urban Heat Island (UHI). The UHI effect has become a significant threat due to increasing population growth and corresponding increasing urbanization. The higher temperatures experienced within urban areas can also be considered potentially hazardous to residents living within these environments. As such, this study applies an exploratory design approach to examine the relationship between land surface temperature (LST) and environmental factors within German cities of various size to determine how heat differs based on environmental context. To carry out the exploratory analysis, LST data will be analyzed in combination with landcover data and urbanization-level data, both of which have been provided by the Deutsches Zentrum für Luft- und Raumfahrt (DLR). LST extracted from satellite thermal imagery is commonly used in the study of urban heat and environmental research. While multiple studies have analyzed LST in combination with landcover data, the urbanization-level data used in the study is unique, having never been previously used in this context. By combining statistical analysis with GIS mapping, the research can examine LST within different urban environments on a regional scale, filling in gaps in existing research and potentially mitigating the impacts of increasing heat stress on urban residents. The first stage of the research utilizes statistical analysis to analyze the UHI effect within cities of various sizes and determine the potential of the novel urbanization-level data in future UHI research while also confirming existence and impact of the intra-urban UHI phenomenon within cities of varying sizes. The second stage of the research will statistically analyze only the high density built (HDB) grid cells of each city – extracted from the urbanization-level data – to determine whether the percentage of ‘more urban’ space or the underlying variables associated with ‘more urban’ spaces (e.g., impervious cover, population density, etc.). have a greater impact on LST variation. Additionally, this section analyzes which underlying variables of ‘more urban’ spaces have greater impact on LST variation and to what extent. The final stage of the research uses landscape metrics to calculate specific indicators of urban form and cluster the cities using these indicators to compare the LST values and determine which commonalities or specific urban characteristics result in higher LST values. Findings have shown unexpected results regarding the impact of city size on LST and indicates that urban form and landcover has a significant impact on LST variation. Additionally, common urban characteristics were shown to be identifiable within German cities, some of which can be attributed to city size, that significantly impact LST variation and may help to predict events of higher LST. Therefore, the exploratory analysis provides knowledge and recommendations for policymakers to help alleviate heat-related risks and increase the sustainability of cities.