Effect of reduced anthropogenic emissions on urban heat island dynamics in Prague

The urban heat island (UHI) effect is driven by land cover changes, reduced vegetation, anthropogenic heat emissions, dense urban morphology, and the thermal properties of construction materials, all of which alter energy balances and elevate temperatures in urban areas. UHI adversely affects thermal comfort, public health, and sustainability. The unprecedented global reduction in anthropogenic activity during the COVID-19 lockdown in 2020 provided a unique opportunity to examine how decreased anthropogenic emissions influence UHI dynamics. While previous studies suggest that lockdown conditions led to declines in atmospheric UHI (AUHI) and surface UHI (SUHI), the extent of these reductions remains uncertain due to confounding meteorological variables and urban-rural dynamics.

This study investigates how the lockdown period (March–April 2020) affected AUHI and SUHI in Prague by controlling for weather variability and urban-rural contrasts. To ensure robust comparisons, we selected meteorologically similar days across the Lockdown period and a Reference period (March–April 2017–2019). SUHI intensity was assessed using MODIS satellite-derived land surface temperature, while AUHI variations were analyzed using near-surface air temperature records from Prague’s meteorological stations. Our results reveal that urban SUHI intensity declined by 15% (0.1 °C), and AUHI in the city center dropped by 0.7 °C compared to the Reference period. Satellite-based observations further indicate a 12% reduction in aerosol optical depth and a 29% decline in nitrogen dioxide levels, supporting the hypothesis that diminished anthropogenic emissions contributed to weakened UHI effects. The highest decrease in mean SUHI was observed on Prague’s outskirts, where rural land cover dominates, highlighting the importance of accounting for urban-rural dynamics when linking SUHI changes to AHF. Our findings advance the understanding of UHI dynamics by demonstrating the effects of reduced anthropogenic activities during the lockdown, providing policymakers with a comprehensive perspective on urban-rural microclimate interactions and their role in shaping the SUHI phenomenon.