Temperature and urban heat island effect in Lublin city in Poland under changing climate

Abstract

This study investigates the characteristics of the temperature regimes at an urban station (Litewski square) in Lublin city in Poland and a nearby rural station (Radawiec), and the Urban Heat Island (UHI) effect in Lublin city. In winter, spring, summer, and autumn at both urban and rural stations frequency distributions of daily minimum (Tmin), and maximum (Tmax) air temperature in 1998–2020 have shifted towards a warmer climate compared to the frequency distributions in 1974–1997. At both stations in 1974–2020, in all seasons, the annual Tmin and Tmax display increasing trends. At Litewski square and Radawiec, Tmax shows increasing trends of 0.083 and 0.088 ºC/year in summer, respectively. This is the largest increase in all four seasons. Furthermore, it is revealed that the heatwaves at both the urban and rural stations have increased in number over time. However, cold waves at both stations show a declining trend. The UHI effect in Lublin city has not increased significantly during 1974–2020. Population in Lublin city has declined over the period 1995–2020, but the population in the surrounding rural counties has increased. It is speculated that this is one of the causes of no clear increase in the UHI intensity. Apart from that, the city’s large green coverage (about 40%) is probably acting as a heating inhibitor. The annual Tmin and Tmax projected by 15 Coupled Model Intercomparison Project Phase 6 (CMIP6) GCMs indicate that the temperature regimes at both urban and rural stations show significant increasing trends during 2015–2100 under the selected SSPs, with the highest increase under high emission scenario (SSP5-8.5) and the lowest increase under the low emission scenario (SSP1-2.6). During 2015–2100, the UHI effect in Lublin city does not show any significant increasing or decreasing trends for the majority of the GCM–SSP combinations.