Annual and monthly analysis of surface urban heat island intensity with respect to the local climate zones in Budapest

Built-up areas with non-natural surface covers generate the urban heat island (UHI) effect. To investigate this in greater spatial extensions, satellite data provide sufficient spatial coverage without unnecessary time lag effect within the region. Moreover, it is very costly to operate a meteorological station system with a suitable density. Although the cost of maintaining satellites is also high, however, a lot of satellite data is available free of charge to users. For instance, surface temperature data derived from MODIS (Moderate Resolution Imaging Spectroradiometer) measurements can be used to obtain surface temperature-based UHI (SUHI) intensity. Due to the variability of built-up density and vegetation cover within the city, different subregions can be characterized by the Local Climate Zone (LCZ) system. The main goal of the paper is to analyse the relationship between the SUHI intensity and the LCZ classes for Budapest. SUHI intensity values were determined relative to the average surface temperature of the surrounding rural areas. Our conclusions clearly show that as building density decreases, the SUHI intensities also decrease. The highest intensities can be found in the city centre, and the lowest SUHI intensities with negative values (i.e. adverse or cooling effect) appear in vegetation-covered LCZ classes. The SUHI intensity variability is generally greater in summer than winter, which can be detected in case of all LCZ classes due to the substantial difference of incoming solar radiation.