Sensitivity of urban heat island intensity to different urban surface descriptions over Warsaw

This study explores how urban land cover affects the formation of an urban heat island (UHI) over Warsaw, Poland. A high-resolution version of the Global Environmental Multiscale (GEM) model was utilized, with the incorporation of the town energy balance (TEB) parameterization at a 1 km resolution. Two specific days, representing spring and late spring, were selected for analysis, and the model was executed both with and without implementing the TEB parameterization. Temperature anomalies within the lower model layers were computed to evaluate the model’s accuracy in simulating air temperatures. When the model’s results were compared with air temperature data from five measurement stations, a noteworthy improvement in model performance was observed, especially in the spring case, with the integration of the TEB parameterization. The impact of urban land cover on UHI was highlighted, revealing the pronounced presence of a nocturnal UHI in both cases when the TEB approach was applied. Additionally, UHI sensitivity to varying surface descriptions was assessed. The results demonstrated that the transition from a predominantly natural environment to extensive urban development led to the exacerbation of nocturnal UHI intensity by 40% during spring and 70% during late spring scenarios.