Analysing the surface temperature of the urban environment during extreme summer heat

The urban environment possesses special characteristics in terms of the energy and radiation budget. Due to direct impacts on human comfort, it is especially important during extreme heat events in summer, which have become and are projected to be longer lasting, more frequent, and more intense in extratropical regions. The 22-year-long time series of continuous MODIS measurements of Terra and Aqua satellites are used to study the surface temperature (ST) as well as the consequent surface urban heat island (SUHI) pattern. In addition, humidity is also involved due to its connection to the energy budget. Here, the urban environment of Budapest (a Central/Eastern European city with 1.7 million inhabitants) is analysed. A significant warming trend can be identified in ST. However, the summer SUHI intensity decreases as the surrounding rural area becomes warmer. When less water is available in the rural area in a drought event, the lack of latent heat facilitates the warming of ST in the rural area similarly to the urban area. Consequently, the SUHI is very weak during hot and dry summers. Such conditions are analysed for selected years (2003, 2007, and 2022), when the compound events of heat and drought occurred. Such detailed analysis aiming to understand the complex processes in the urban environment is essential in order to develop effective adaptation strategies to the upcoming challenges of climate change with possible adverse effects to the urban population’s comfort. As a specific example, the analysis of in-situ local measurements is also added to the study in order to evaluate children’s playground areas during such extreme heat conditions.

This work has been implemented by the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014) project within the framework of Hungary's National Recovery and Resilience Plan supported by the Recovery and Resilience Facility of the European Union.