Heat load assessment in Central European cities using an urban climate model and observational monitoring data

Abstract

Diurnal variability of spatial pattern of air temperature was studied in five cities in Central Europe: Bratislava (Slovakia), Brno (Czech Republic), Kraków (Poland), Szeged (Hungary) and Vienna (Austria), during one of the heat waves in 2015 (4–14 August), with the application of micro-climate model MUKLIMO_3. 8th August was chosen to study in detail the urban heat load at 10.00, 16.00, 22.00 and 4.00 CEST. Local Climate Zones concept was used to supply data for the model and for the interpretation of the results obtained. Model outcomes were validated with measurement data from 86 points belonging to the networks which operate in the cities studied. The results obtained show that among urban LCZ, the highest heat load was observed for LCZ 2 and 3 from 16.00 to 4.00, while at 10.00 there is no such clear pattern. Unlike forested areas, open green areas can contribute to the generation of high air temperature: >35 °C during day time and >30 °C during night time. Important factors controlling the intra-zonal and inter-zonal variability of air temperature in particular LCZs are the local environmental conditions. During the day time, diversified relief in the area of the city and its vicinities generates higher heat load in the valleys’ floors than in areas located above, both in rural and urban areas. The same landforms experience lower heat load during the night time due to air temperature inversions effect.