Comparison of thermal conditions in different intra- and inter-urban structures of different Balkan cities during the summer period

Intensive urbanization and climate change are issues that are affecting majority of the urban areas around the world. Traditional artificial materials that are dominant in most of the cities are enhancing thermal stress that is very pronounced in the summertime especially in urban areas.  Different local and micro locations develop their own specific thermal conditions according to type of the materials that are dominant in the area. Green areas can contribute to improving thermal conditions of the area, but there is few in situ measurements to support those statements.

The main aim of the study is to investigate if there are intra- and inter-urban differences or similarities in thermal conditions in cities of different sizes and climate types. Micro-climate conditions (Ta, RH, v and Tg, 1 min. temporal resolution) were assessed using the in situ measurements with Kestrel 5400 Heat Stress Trackers in urban areas during the summer period. The measurement campaigns were conducted in five cities located in three Balkan countries: Serbia (Belgrade and Novi Sad), Bosnia and Herzegovina (Banja Luka and Trebinje), and Slovenia (Ljubljana). The first results indicate that there are significant differences in micro-climatological conditions of different local climate zones within the cities, which confirms that there are intra- and inter-urban differences within the cities and are related to the level of urbanization and presence of natural areas. For example, in Belgrade measurements show that differences in air temperature between densely built-up areas (LCZs 2 and 8) and green areas (LCZs A and B) are up to 7 ºC. Significant differences among the same LCZ are also recorded, depending on the level of shade provided by the urban configuration. Similar results are recorded in other cities where the measurements were performed. The results also show that shade and short- and long-wave radiation plays the most important role when it comes to reducing the outdoor thermal stress. The results are in good accordance with the previous studies that also reported more comfortable conditions in less built-up local climate zones with higher amount of greenery. This kind of assessments contribute to creating more sustainable urban environments that are resilient to climate change and increased thermal stress and extreme events in urban areas.