Thermal maps were developed using satellite data for the urban areas of Bratislava, following the co-creation process with the cities, in order to provide information for the thermal risk analysis planned in the ARCH project. Current satellite missions, providing imagery in the Thermal InfraRed (TIR) spectral region at 60-100 meters of spatial resolution, give the possibility to estimate the land surface temperature (LST) and highlight the main surface thermal anomalies, i.e. areas where the surface temperature has a value significantly different from the background. Thermal anomalies are potentially related to underground energy sources or to land use and coverage variations, e.g. urban areas, where the urban heat island (UHI) phenomena can be observed. UHI is considered as one of the most important problems of overheating in urban areas and result, amongst others, in increases of urban smog, increased need of air-conditioning in hot climate regions (with a consequence increasing of energy consumption), and impacts on human health.For this project, the Temperature and Emissivity Separation (Gillespie et al., 1998), for ASTER data) and single-channel algorithm (for Landsat 8, inverting Radiative Transfer Equation) have been used.For Bratislava9ASTER data cloud-masked and night-time estimated Land Surface Temperature have been collected.

LST processed for Bratislavatest site using ASTER data:

- 17 May 2011

- 19 July 2014

- 23 August 2015

- 30 May 2016

- 22 November 2016

- 29 November 2016

- 15 October 2017

- 8 March 2018

- 11 November 2018

To refine this analysis and evaluate potential Urban Heat Islands, the Principal Component Analysis (Fernández et al., 2003; Ruiz et al., 2015; Müller et al., 2014) of the 10 LST image for Bratislavahas been done.