For a better understanding of the causes and effects of urban heat islands (UHIs) different studies took place in different cities and towns using both empirical methods and numerical models. The results indicated that the development of heat islands is determined not just by physical and morphological characteristics of the urban surface, but that weather conditions may also have a significant effect. Some statistical and dynamical characteristics of an urban heat island are shown on the example of Debrecen. Hourly temperature data, measured on an automatic urban climate station installed in the town (on the ground of ATOMKI), and on Agrometeorological Observatory located on the outlying areas (near Kismacs) were used for the study. Using air temperature data, daily and seasonal variation of the intensity of the heat island was quantified, and connections with macrocirculation types were explored. The daily variation of UHI intensity in Debrecen showed its stronger effects during the daylight time. The seasonal dynamics of urban heat excesses is characterized by a pronounced summer maximum both in daytime and night-time values. However, lower heat island values were observed in the winter period. Relationships were found between the UHI intensity and macrocirculation types: strong thermal excesses correspond mainly to anticyclonic calm weather, and weaker periods to cyclonic rainy weather.

Eredeti fellelhetőség: mtmt.hu