Ágnes Gulyás

Land-use and meteorological aspects of the urban heat island

This study examines the influence of urban and meteorological factors on the surface air temperature field of the medium-sized city of Szeged, Hungary, using mobile and stationary measurements under different weather conditions between March and August 1999. This city, with a population of about 160 000, is situated on a low, flat flood plain. Efforts have been concentrated on investigating the maximum development of the urban heat island (UHI). Tasks include the determination of the spatial distribution of seasonal mean maximum UHI intensity and modelling of existing conditions in the period being studied. Multiple correlation and regression analyses are used to examine the effects of urban parameters (land-use characteristics and distance from the city centre determined in a grid network) and of meteorological parameters (wind speed, temperature) on thermal conditions in the study area. The results indicate isotherms increasing in regular concentric shapes from the suburbs towards the inner urban areas where the mean maximum UHI intensity reaches more than 3°C in the studied periods. A strong relationship exists between urban thermal excess and distance, as well as built-up ratio. In contrast, meteorological conditions do not have any significant effect on the UHI intensity at the time of its maximum development. Copyright

Subjective estimations of thermal environment in recreational urban spaces—Part 2: international comparison

The present paper is the second part of our study in which we compare the results obtained in Szeged (Hungary) with those achieved through earlier outdoor thermal comfort projects based on simultaneous questionnaire surveys and on-site meteorological measurements. The main characteristics of the selected studies—conducted in Hungary, Sweden, Portugal, Canada, Taiwan and across Europe in the frame of project RUROS—are reviewed, emphasizing the common features and also the discrepancies in the applied methodology. We discuss their potential effects on the evolution and interpretation of the results concerning the subjective assessment of the thermal environment. Another aspect of the comparison focuses on the regional climatic differences naturally ensuing from the various locations, which left their marks on the results related to both physiological acclimatization and mental adaptation. The compared results of different studies include correlation coefficients expressing interrelationships between the different aspects of subjective estimations (thermal sensation, perceptions, preferences) and also between subjective assessments and the corresponding meteorological parameters. We compare neutral temperatures (expressed in physiological equivalent temperature, PET) which arose for Taiwan and Hungary, as well as thermal sensation zones for local inhabitants. Subjectively assessed temperature values of Sweden and Hungarians are analyzed according to the measured air temperature. According to our experiences the methodology should be standardized for the level of field surveys and also for the level of data processing in order to make the data collected in different locations comparable.

Temporal Differences of Urban-Rural Human Biometeorological Factors for Planning and Tourism in Szeged, Hungary

Heat load and cold stress can provoke annoyance and even health issues. These climatic situations should be avoided by tourists and locals to prevent negative experiences. Thermal comfort indices are required, as they combine meteorological and thermophysiological parameters. The Physiologically Equivalent Temperature (PET) is easy to understand and interpret also for nonexperts like tourists or decision-makers. The Hungarian Meteorological Service and the University of Szeged run an urban and a rural weather station close to Szeged, which build the basis for the human biometeorological analysis for a twelve-year period between 2000 and 2011. The maximum, mean, and minimum air temperature of both stations were compared to detect the differences of thermal dynamics. Heat and cold stress are quantified by analyzing the PET frequencies at 14 CET. The air temperature of urban areas is on average 1.0°C warmer than rural areas (11.4°C). Heat stress is more frequent in urbanized areas (6.3%) during summer months at 14 CET, while thermal acceptance is more frequent for surrounding rural areas (5.9%) in the same period. The Climate-Tourism/Transfer-Information-Scheme is a possibility to present the meteorological and human biometeorological data which is interesting for decision-making and tourism in a well-arranged way.

The impact of façade orientation and woody vegetation on summertime heat stress patterns in a Central-European square : comparison of radiation measurements and simulations

Increasing summertime air temperature deteriorates human health especially in cities where the warming tendency is exacerbated by urban heat island. Human-biometeorological studies shed light on th ...