Analysis of micro climatic variations and the urban heat island phenomenon in the city of Vienna (original) (raw)
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The extent and implications of the urban heat island phenomenon in Central European region
Metropolitan areas worldwide display highly diverse microclimatic circumstances that are influenced by a variety of morphologies, structures, materials (particularly urban surface properties), and processes (mobility, industry, etc.). This diversity influences the intensity and extent of the urban heat island effect (UHI) in different cities. UHI may be understood in terms of emerging divergence between micro-climatic conditions in the city proper versus the rural environs. Significantly higher temperatures are observed in the urban area as compared to the surrounding suburban and rural neighborhoods. A further rise in the appearance and intensity of UHI phenomena is to be expected in the coming years due to the on-going population increase in urban areas. Furthermore, the UHI effect is believed to be related to (and worsened by) the climate change. Thereby, the rise of global temperatures is likely to affect not only the health of the urban population (urban heat distress, pedestrian discomfort) but also the energy performance of the built environment (higher outdoor air temperatures lead to a significant increase in buildings' energy use for cooling). In this context, this paper presents the results of an on-going EU-supported research project, which investigates the urban heat island phenomena in a number of urban regions in Central European countries (Stuttgart, Warsaw, Prague, Padua, Ljubljana, Modena, and Budapest). Toward this end, we pursue a two-fold approach. First detailed information regarding urban and rural climate in a 7-day period for each of the participating cities was collected and analysed. The results show a considerable variance, which, if ignored, would lead to major uncertainties in inferences made based on performance simulation. Secondly, long term data on rural and urban climate was obtained for all participating cities and included in the analyses.
Urban heat island phenomenon in Central Europe
icaud.epoka.edu.al
The urban heat island (UHI) phenomenon is characterized by significantly higher temperatures in metropolitan areas as compared to the surrounding suburban and rural neighborhoods. In this context, this paper presents a preliminary report pertaining to an ongoing EU-supported research project, which investigates the urban heat island phenomena in Central Europe. First, the background and general scope of the UHI phenomena are discussed. Subsequently, the paper investigates the manifestation of the urban heat islands phenomena (especially in the city of Vienna) and evaluates possible mitigation and adaptation strategies.
Land Use Changes in a Peri-Urban Area and Consequences on the Urban Heat Island
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The effect of urbanization on microclimatic conditions is known as “urban heat islands”. In comparison with surrounding rural areas, urban climate is characterized by higher mean temperature, especially during heat waves and during nights. This results in a higher energy requirement for air conditioning in buildings and in a greater bioclimatic discomfort for urban populations. The reasons of this phenomena are ascribable principally to the increase of solar radiation storage and to the decrease of dissipation of water by evapotranspiration in urban environment respect to rural ones. The aim of this paper is to give a quantification of the air temperature increase due to an urbanization process. This quantification is conducted by comparing surface energy balance (incoming and outcoming radiation and turbulent fluxes) in urbanized area versus rural areas. This quantitative approach will be validated using a fluidodynamic model (Envi-Met) in a case study area representative of one am...
Relevance of Thermal Indices for the Assessment of the Urban Heat Island
Counteracting Urban Heat Island Effects in a Global Climate Change Scenario, 2016
Urban areas, with their specific characteristics, modify the atmosphere and produce their own meso-and micro climate. The major aspect of this chapter is the discussion of methods for the quantification and assessment of the urban microclimate and the most known and worldwide studied phenomenon, the Urban Heat Island (UHI). Four urban measurement stations and one rural measurement station are used to quantify the temporal and spatial climatic characteristics in Stuttgart, Germany. For the quantification of the urban micro-climate and the UHI human thermal, comfort indices were applied. These indices, namely Physiologically Equivalent Temperature and the Universal Thermal Climate Index, are used to describe the integral effect of urban thermal atmosphere, based on the energy exchange of the human body. These indices, following the concept of equivalent temperature, are applied to quantify the integral effect of air temperature, air humidity, wind and radiation fluxes, expressed as mean radiant temperature.
Theoretical and Applied Climatology, 2016
Meteorological conditions have a remarkable impact on urban climate similarly to other local and microscale climates. Clear skies and calm weather are advantageous for the development of the urban heat island (UHI). There are numerous studies on the spatial and temporal features of the phenomenon. Much less attention is paid, however, to the meteorological conditions of UHI development. The aim of the present paper is to reveal the characteristics of the changes in the frequencies of advantageous and disadvantageous meteorological conditions for UHI development on the basis of a 50-year-long time series. Meteorological condition categories of UHI development have been established on the basis of wind speed values, cloudiness, and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence of condition categories of UHI development were determined first. Advantageous and moderately advantageous conditions were found to be dominant in the time series. Linear trend analysis revealed a significant increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous conditions was analyzed for the years, seasons, and months of the study period as well. Spring and summer (April and June) produced significant increasing trends of frequencies of advantageous conditions, while winter (with the exception of February) and autumn did not show significant increase of those frequencies. Change-point analyses detected a significant increase in the frequency of advantageous conditions in the time series at the turn of 1981/1982 especially in the summer and spring months. Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter significantly.
The Variance of the Urban Microclimate in the City of Vienna, Austria
Proceedings of the 2nd ICAUD International Conference in Architecture and Urban Design , 2014
Metropolitan areas worldwide display highly diverse microclimatic conditions that are believed to be influenced by a variety of parameters: morphologies, structures, materials (particularly urban surface properties), and processes (mobility, industry, etc.). The density of urban structures and sealing of urban areas may lead to higher heat storage, thus increasing the daily urban air temperatures. In order to understand some of the relationships between the microclimates of urban neighborhoods, human activity and thermal environments that regulate microclimates, this paper investigates the intra-city microclimatic variance in several locations in the city of Vienna, Austria, which effectively portray urban and suburban climatic conditions. Specifically, we explore possible deviations of local (site-specific) microclimatic conditions from those captured by near-by stationary weather stations.
Recent challenges in the realm of urban studies concern better understanding of microclimatic conditions. Changes in urban climate affect cities at local and global scales, with consequences for human health, thermal comfort, building energy use, and anthropogenic emissions. The extent of these impacts may vary due to different morphologies and materials of the built environment. The present contribution summarizes the results of a multi-year effort concerned with the extent and implications of urban heat in Vienna, Austria. For this purpose, high-resolution weather data across six locations are obtained and analyzed. This allowed for an objective assessment of urban-level climatic circumstances across distinct low-density and high-density typologies. Subsequently, a systematic framework was developed for identification of essential properties of the built environment (geometric and material-related) that are hypothesized to influence microclimate variation. Results point to a number of related (positive and negative) correlations with microclimatic tendencies. Additionally, the impact of this location-specific weather data on building performance simulation results is evaluated. The results suggest that buildings' thermal performance is significantly influenced by location-specific microclimatic conditions with variation of mean annual heating load across locations of up to 16.1 kWhm −2 ·a −1. The use of location-independent weather data sources (e.g., standardized weather files) for building performance estimations can, thus, result in considerable errors.
Comparison of different methods for the assessment of the urban heat island in Stuttgart, Germany
International Journal of Biometeorology, 2014
This study of the urban heat island (UHI) aims to support planning authorities by going beyond the traditional way of urban heat island studies. Therefore, air temperature as well as the physiologically equivalent temperature (PET) were applied to take into account the effect of the thermal atmosphere on city dwellers. The analysis of the urban heat island phenomenon of Stuttgart, Germany, includes a longterm frequency analysis using data of four urban and one rural meteorological stations. A (high resolution map) of the UHI intensity and PET was created using stepwise multiple linear regression based on data of car traverses as well as spatial data. The mapped conditions were classified according to the long-term frequency analysis. Regarding climate change, the need for adaptation measures as urban greening is obvious. Therefore, a spatial analysis of quantification of two scenarios of a chosen study area was done by the application of a micro-scale model. The nocturnal UHI of Stuttgart is during 15 % stronger than 4 K in the city center during summer when daytime heat stress occurs during 40 %. A typical summer condition is mapped using statistical approach to point out the most strained areas in Stuttgart center and west. According to the model results, the increase in number of trees in a chosen area (Olga hospital) can decrease PET by 0.