engleski

Surface urban heat islands of Zagreb and Split (Croatia) – local climate zone based definition

Urban heat island is a climate phenomenon whose negative effects are emphasised during the summer months, mostly due to accumulation of solar irradiation and various anthropogenic heat sources in the city's built-up area. During these months heat stress is high and can put at health risk a large number of people, especially the most vulnerable ones as elder and children. In order to examine climate features of two biggest Croatian cities, Zagreb and Split, we defined their local climate zones (LCZ) which provided a relevant basis for further research. The link between LCZ's and temperature was investigated by deriving land surface temperature (LST) from Landsat scenes using Google Earth Engine (GEE), a cloud based geospatial analysis platform. That allowed for a wide spatial coverage of surface urban heat island (SUHI) and its investigation on different spatial scales. Furthermore, LCZ's were characterised by normalized difference vegetation index (NDVI), which we derived from GEE as well. Comparison of SUHI between Zagreb and Split is valid as the Landsat passing time difference between cities is less than a minute. Results revealed the highest LST in compact LCZ's in both of the cities and opposed to that, natural LCZ's such as LCZ A (dense trees), LCZ B (scattered trees) and LCZ G (water) had the lowest LST. Also, correlations between LST and NDVI proved to be significantly negative, which points out cooling effect of vegetation. This work also indicates the added value LCZ mapping has in SUHI investigation.

surface urban heat island, Zagreb, Split, Google Earth Engine, Landsat, land surface temperature, NDVI

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