Differences in human comfort conditions within a complex urban enviroment : a case study

Several complex thermal indices (e.g. Predicted Mean Vote and Physiological Equivalent Temperature) have been developed in the last decades to describe and quantify the thermal environment of humans and the energy fluxes between body and environment. Compared to open spaces/landscapes the complex surface structure of urban areas creates an environment with special microclimatic characteristics, which have a dominant effect on the energy balance of the human body. In this study, outdoor thermal comfort conditions are examined through a field survey in Szeged, a South-Hungarian city (population 160,000). The intensity of radiation fluxes depends on several factors, such as surface structure and housing density. Since our sample area is located in a heavily built-up city centre, radiation fluxes are mainly influenced by narrow streetsand several 20-30 year old (20-30 m tall) trees. Special emphasis is given to the húman-biometeorological assessment of the microclimate of complex urban environments through the application of the thermal index PET. The analysis is carried out by the utilization of the RayMan model. Bioctimatic conditions of sites located close to each other but shaded differently by buildings and plants are compared. According to the results differences in the PET index amongst these places can be as high as due to the different irradiation

Selected examples of bioclimatic analysis applying the physiologically equivalent temperature in Hungary

Összefoglalás : Cikkünkben bioklimatológiai elemzést végzünk az ún. Fiziológiailag Equivalens Hőmérséklet (PET) index felhasználásával először Magyarország egész területén (1 km-es felbontású bioklíma térkép segítségével). A bioklíma térképek a PET index térbeli eloszlását mutatják Magyarországon egy téli (február) és egy nyári (augusztus) hónapban. Majd két szinoptikai állomás (Szombathely és Sopron) 1996 és 1999 között rögzített adataiból számított PET értékek alapján részletes elemzésben hasonlítjuk össze a két város főbb bioklimatológiai jellegzetességeit. Summary : In this study, maps were created that show the geographical distribution of Physiologically Equivalent Temperature (PET) values in February and August for the area of Hungary, with a resolution of 1 km. For the further analysis of the thermal bioclimate, data of the synoptical stations of Szombathely and Sopron, recorded from 1996 to 1999, has been used. This study provides a detailed analysis and comparison of the bioclimatic properties of these locations

Connection between phenological phases and urban heat island in Debrecen and Szeged, Hungary

A local climate with special spatial structure (e.g. heat island) is formed within the settlement compared to outside open spaces. We presume that these climatic modification affects the phenological and phenometrical properties of the urban vegetation. For this study we have chosen two medium-sized Hungarian cities (Szeged and Debrecen), with urban areas over 30 km2 and with population between 160 and 200 thousand. The phenological and temperature observations have been taken in grid networks in spring of 2003. As a good observable plant, forsythia (Forsythia suspensa) was the object of our examination because this species occurs in the 60-70% of the areas of both cities. The time of the different phenological phases was monitored in a daily fashion. According to the results there is significant correlation between the spatial distributions of the timing of these phenological phases and of the intensity of the urban heat island. The strongest correlation occurs between the UHI intensity and the date of 100% flowering in Debrecen

URBAN TREE CROWN PROJECTION AREA MAPPING WITH OBJECT BASED IMAGE ANALYSIS FOR URBAN ECOSYSTEM SERVICE INDICATOR DEVELOPMENT

The continuous expansion of built-up areas in the urban environment at the expense of green spaces brings up numerous environmental problems, for which accurate and efficient solutions should be found. The assessment of ecosystem services developed within the field of landscape ecology is playing an ever more important role in environmental sciences and thus may offer suitable answers. Such assessments can be carried out by developing indicators. Accordingly, in the case of urban trees, an accurate quantitative characterization of their services (such as e.g. carbon sequestration, pollutant removal and microclimate regulation) is also needed. The aim of this study is to establish a generally applicable method based on indicator development, using widely available data. In the case of urban green spaces there are several services for which the development of proper indicators and evaluation methods requires a delineation of tree crowns, or at least the crown projection area. Accordingly, in our work, we map the crown projection area of a large and popular urban park of Szeged, Széchenyi square, using object-based image analysis on UltraCamD digital orthophotos. Following a multiresolution segmentation the classification of the resulting objects was carried out, using the eCognition image analysis software. Besides fulfilling the policy objectives related to the evaluation of urban ecosystem services, the produced crown base can also be used in several other types of urban ecological and urban climatological studies (e.g. urban climate modelling, human-comfort assessment). In this paper the first results are presented

Népszerű városi fafajok árnyékolóképességének vizsgálata Szegeden

A városi faállomány számos aspektusból kedvezően befolyásolja egy város ökológiai állapotát. Például, klímamódosító potenciálja révén a fás vegetáció pozitívan hat a városi lakosság hőérzetére és komfortérzetére. A mikroklimatikus hatások feltárása céljából végzett terepi mérések, valamint modellfuttatások is kimutatták, hogy a fák elsősorban árnyékhatásuk révén képesek enyhíteni az emberi szervezetet érő hőstressz mértékét. A napsugárzás redukciójának hatékonyságát a lombozat transzmisszivitásának (napsugárzásátereszt őképessége) mérőszámával írhatjuk le, melynek értéke nem csupán fajonként változik, de a lombkorona évszakos változásának és egészségi állapotának is függvénye. Ebben a tanulmányban négy, magyarországi viszonyok között gyakran előforduló városi fafaj (kislevelű hárs – Tilia cordata, japánakác – Sophora japonica, nyugati ostorfa – Celtis occidentalis és fehér vadgesztenye – Aesculus hippocastanum) árnyékolóképességét vizsgáljuk. A városi fás vegetáció – közép-európai klimatikus körülmények között kifejtett – kisléptékű hatására vonatkozóan még kevés az ismeretünk, ezért munkánkkal szeretnénk elősegíteni jövőbeli, ezzel foglalkozó tanulmányok megszületését. Ebből kifolyólag nagy hangsúlyt fektetünk a kutatás módszertani alapjaira, valamint kitérünk a gyakorlati megvalósítás nehézségeire is

Adaptation of UFORE-Hydro model for Szeged and the Southern region of the Great Hungarian Plain based on local meteorological database

Urban environments are very different from natural ones in many cases. The geometry of the buildings and the various artificial surface elements can significantly influence the microclimatic and hydrological processes. In urban areas, the surface is mostly artificial and it is hard to find natural, undisturbed surfaces, in addition, the vast majority of soil surfaces are generally under strong anthropogenic influence. Models can provide a comprehensive view of the hydrological processes in the city and can help to investigate the different impacts of them. In this study, our aim is to introduce the preparation of a widely applicable model (UFORE-Hydro) for Hungarian pilot areas. Thus, we intend to introduce the procedure of preparing the weather and evaporation files and their local databases which we used for the model

Mapping of rainwater harvesting potential, a case study of Szeged, Hungary

In urban environment, rainwater harvesting is a good solution to make the water management sustainable. The rainwater harvesting potential of a whole city gives information to the urban planners about the building possibilities of real collecting systems. In our work, with the help of hydrological modeling we create urban micro-watersheds, which based on the roof of buildings. Our expected results can give a comprehensive picture of rainwater harvesting possibilities in urban areas