AN OVERVIEW OF RECENT RESEARCH ON THE LJUBLJANA HEAT ISLAND

Research into Ljubljana’s urban heat island has gained momentum in recent years. After a preliminary study in winter 2020/2021, the Department of Geography of the Faculty of Arts, University of Ljubljana and its partners conducted a more extensive study in 2021/2022 to compare the intensity of the heat island in the period 1998–2022. While in 1998 the most intense heat island occurred in December, in 2021/2022 winter is the season with the mildest heat island (4 °C), fall the second strongest (5.1 °C), and summer with the strongest heat island (5.9 °C) in anticyclonic weather. Summer thus maintains similar values, while winter becomes weaker, which is a consequence of climate change and the increasingly green and mild winters in Ljubljana. The measurements have also shown that while the heat island in Ljubljana retains the uniform shape observed in 1998, the secondary peak in the east of the city is becoming stronger. When the heat island is less pronounced, it has the shape of a Y, but when it becomes stronger, it takes on the shape of an X. Once we determined the basic characteristics of the heat island and its extent, we began mapping the heat island in real time in 2024. The 2020/2021 and 2021/2022 studies were based on a combination of mobile bicycle and car measurements supplemented by stationary measurements. The most recent study is based on a dense network of stationary measurements in the urban area. The main aims of this study are the dynamic mapping of the urban heat island in real time and the identification of hotspots in the city where urban heat island mitigation measures are needed to reduce heat stress during the summer months.