Showing papers on "Urban climate published in 2003"

Two decades of urban climate research: a review of turbulence, exchanges of energy and water, and the urban heat island

Abstract: Progress in urban climatology over the two decades since the first publication of the International Journal of Climatology is reviewed. It is emphasized that urban climatology during this period has benefited from conceptual advances made in microclimatology and boundary-layer climatology in general. The role of scale, heterogeneity, dynamic source areas for turbulent fluxes and the complexity introduced by the roughness sublayer over the tall, rigid roughness elements of cities is described. The diversity of urban heat islands, depending on the medium sensed and the sensing technique, is explained. The review focuses on two areas within urban climatology. First, it assesses advances in the study of selected urban climatic processes relating to urban atmospheric turbulence (including surface roughness) and exchange processes for energy and water, at scales of consideration ranging from individual facets of the urban environment, through streets and city blocks to neighbourhoods. Second, it explores the literature on the urban temperature field. The state of knowledge about urban heat islands around 1980 is described and work since then is assessed in terms of similarities to and contrasts with that situation. Finally, the main advances are summarized and recommendations for urban climate work in the future are made. Copyright © 2003 Royal Meteorological Society.

Impact of urbanization and land-use change on climate

Abstract: The most important anthropogenic influences on climate are the emission of greenhouse gases1 and changes in land use, such as urbanization and agriculture2. But it has been difficult to separate these two influences because both tend to increase the daily mean surface temperature3,4. The impact of urbanization has been estimated by comparing observations in cities with those in surrounding rural areas, but the results differ significantly depending on whether population data5 or satellite measurements of night light6,7,8 are used to classify urban and rural areas7,8. Here we use the difference between trends in observed surface temperatures in the continental United States and the corresponding trends in a reconstruction of surface temperatures determined from a reanalysis of global weather over the past 50 years, which is insensitive to surface observations, to estimate the impact of land-use changes on surface warming. Our results suggest that half of the observed decrease in diurnal temperature range is due to urban and other land-use changes. Moreover, our estimate of 0.27 °C mean surface warming per century due to land-use changes is at least twice as high as previous estimates based on urbanization alone7,8.

An approach for mapping large-area impervious surfaces: synergistic use of Landsat-7 ETM+ and high spatial resolution imagery

Abstract: A wide range of urban ecosystem studies, including urban hydrology, urban climate, land use planning, and resource management, require current and accurate geospatial data of urban impervious surfaces. We developed an approach to quantify urban impervious surfaces as a continuous variable by using multisensor and multisource datasets. Subpixel percent impervious surfaces at 30-m resolution were mapped using a regression tree model. The utility, practicality, and affordability of the proposed method for large-area imperviousness mapping were tested over three spatial scales (Sioux Falls, South Dakota, Richmond, Virginia, and the Chesapeake Bay areas of the United States). Average error of predicted versus actual percent impervious surface ranged from 8.8 to 11.4%, with correlation coefficients from 0.82 to 0.91. The approach is being implemented to map impervious surfaces for the entire United States as one of the major components of the circa 2000 national land cover database.

Effects of Urban Development on Floods

Abstract: Over the past century, the United States has become an increasingly urban society. The changes in land use associated with urban development affect flooding in many ways. Removing vegetation and soil, grading the land surface, and constructing drainage networks increase runoff to streams from rainfall and snowmelt. As a result, the peak discharge, volume, and frequency of floods increase in nearby streams. Changes to stream channels during urban development can limit their capacity to convey floodwaters. Roads and buildings constructed in flood-prone areas are exposed to increased flood hazards, including inundation and erosion, as new development continues. Information about streamflow and how it is affected by land use can help communities reduce their current and future vulnerability to floods.

URBAN CENTERS: An Assessment of Sustainability

Abstract: As increasing proportions of the world's population, production, and consumption become concentrated in urban areas, the need for urban development patterns that are more ecologically sustainable becomes obvious. A large proportion of the world's urban population also has needs that are unmet. We review the scale and nature of urban change worldwide, the environmental impacts of these changes, and the potentials and the difficulties in better meeting sustainable development goals in urban centers. The discussion of the interaction between city-based production and consumption and the resources and sinks on which these rely that are outside city boundaries is a reminder that the goal is not sustainable cities but cities that contribute to sustainable development within their boundaries, in the region around them, and globally.

Influence of single and small clusters of trees on the bioclimate of a city: a case study

Abstract: In this study, experimental investigations were conducted at the Fahnenbergplatz in the northern part of the city center of Freiburg in southwest Germany. The objective of this study was to quantify the thermal and air pollution effects of urban trees on urban climate and human bioclimate in cities. EXPERIMENTAL SITES AND DATABASE Abstract. This study examines the effects of single trees and small clusters of trees on the bioclimate of a city. Investigations of the thermal environment and air quality of the urban climate were carried out on September 19 and September 29, 2000, at Fahnenbergplatz, in the northern city center of Freiburg in southwest Germany. The study area, approximately 1,700 m 2 , contains 12 horsechestnut trees (Aesculus hippocastanum) of different ages and sizes. The positive effect of trees on the thermal environment and air quality component was confirmed by the study. In particular, the mean radiation temperature T mrt , and the human biometeorological thermal index known as the physiological equivalent temperature (PET) showed distinct differences between areas with trees and areas without trees, despite the small size of the investigation area. A high reduction potential for nitrogen oxides and ozone was found inside the tree crowns, but outside the crowns there was no measurable reduction. The most important result regarding volatile organic compounds (VOCs) was the absence of terpene emissions from the horsechestnuts. Similarly, no isoprene emissions from horsechestnuts were found. Therefore, horsechestnut trees have a very small ozone- forming potential.

Household Consumption and Ecological Footprints in Norway – Does Urban Form Matter?

Abstract: The research presented in this article shows that the extent of environmentally harmful household consumption varies substantially with the physical/structural conditions in housing areas. The empirical results regarding urban size, density, and distance to the city centre can be related to the concept of the compact city. This is a concept which has been highly focused on in the 1990s discourse on sustainable urban development, and the amount of international research literature has become quite impressive. The authors' research supports the assumption that compact urban structures would lead to reductions in the ecological footprints of households and their houses. Firstly because shorter internal distances between the houses and public and private services give less mobility. Secondly because dense and concentrated types of housing give less energy use for heating and other technical equipment. In addition other forms of environmentally harmful consumption – the material housing consumption – are also less extensive in compact urban structures.

Objective method for classifying air masses: an application to the analysis of Buenos Aires' (Argentina) urban heat island intensity

Abstract: ¶During recent years, numerous studies have examined the Buenos Aires urban climate, but the relationship between large-scale weather conditions and the Buenos Aires urban heat island (UHI) intensity has not been studied. The goal of this paper is to apply an objective synoptic climatological method to identify homogeneous air masses or weather types affecting Buenos Aires during winter, and to relate the results to the UHI intensity. A K-means clustering method was used to define six different air masses considering the 03:00, 09:00, 15:00 and 21:00 LT surface observations of dry bulb temperature, dew point, cloud cover, atmospheric pressure and wind direction and velocity at Ezeiza, the most rural meteorological station of the Buenos Aires metropolitan area (Fig. 1). Results show that the mean UHI intensity is at its maximum (2.8 °C) a few hours before sunrise when conditions are dominated by cold air masses associated with cold-core anticyclones, weak winds and low cloud cover. Inverse heat islands are found during the afternoon for all air masses indicating that surface processes are not dominant at that time. The relatively infrequent and warmest air mass is the only one that presents a mean negative urban-rural temperature difference (−0.1 °C) during the afternoon with the smallest diurnal cycle of the UHI intensity probably due to the prevailing high humidity and cloudy sky conditions. The paper provides an insight into the Buenos Aires urban–rural temperature difference under a variety of winter weather types and results could be useful to improve local daily temperature forecasts for the metropolitan area of Buenos Aires on the basis of the routine forecasts of weather types.

LIFE CYCLE COSTS OF GREEN ROOFS - A Comparison of Germany, USA, and Brazil -

Abstract: Within the last decades, the trend to ever larger dwellings and the increases in industry and traffic have resulted in the continuous growth of cities. The settlement surface in Germany has doubled within the last 40 years and present growth amounts to 1.1% per year. In the USA, the built on surface extends by 3% per year; in Brazil this number may be much higher. Together with increasing emissions, especially caused by traffic, industry and domestic burning, this increase in settlement surface has led to a noticeable impairment of the urban climate. The climate of cities, in comparison to the climate of open land, in most cases has negative effects on urban inhabitants. For example, sleep disturbances and heart disease may be more prevalent. The limited available space in cities makes roof gardens an attractive possibility to improve the urban situation. In Europe, green roof technology has become increasingly important within the last 20 years. In the USA, green roof technology started two years ago and is now growing rapidly. Use of green roofs in Brazil is infrequent, but there, as in all countries, a substantial benefit of roof planting is the economic gain. This work presents these advantages by comparing green roofs with other kinds of roofs. The work presented here is preliminary, and is to be continued in the context of a thesis (diploma). Our first results should be useful for planners, architects, builders, and other experts involved in roof greening. The authors are looking forward to receive detailed information to calculate the benefits as well as possible.

Enhancing sport-hunting opportunities for urbanites.

Abstract: Recent declines in recreational sport-hunting participation rates result from a variety of societal and cultural changes as well as extensive changes in the distribution f the United States population. Concurrently, natural-resource ag ncies are undergoing broad changes in focus and goals, with holistic ecosystem management competing with traditional game management for limited financial resources. We believe that recreational hunting is an important cultural element that should remain a mainstream recreational ctivity and should continue to have a significant place in natural-resource ag ncies. Given the transition of the United States population to a more urbanized society, new innovative programs need to be developed to recruit and retain recreational sport hunters from urban population centers that provide \"successful\" hunting experiences. We identify several components that will be essential to the success of these programs, uch as providing a reasonable xpectation of success or accomplishment (e.g., harvesting an animal), providing sport-hunting opportunities near urban population centers, and providing opportunities that are sensitive to the needs of diverse groups (e.g., minority, gender). We propose 2 solutions for providing recreational hunting opportunities to residents of urban areas: 1) establishing crop fields to attract mourning doves (Zenaida macroura) nd 2) implementing put-and-take hunting under certain restrictions. We recognize many possible problems with these suggested programs. Natural-resource professionals have strong opinions about these issues, but we believe discussions are needed if hunting isto remain a mainstream recreational ctivity. These dialogues need to 1) address the role of recreational hunting in resource agency policies and programs, 2) identify innovative programs to educate, introduce, and retain urban residents in recreational hunting, and 3) identify innovative programs to provide urban hunters with experiences similar to those we have proposed. If we fail to recognize the emerging societal, cultural, and professional changes impacting sport-hunting participation rates, this activity likely will become an anachronism.

Rural and urban hydrology

Abstract: What do you do to start reading rural and urban hydrology? Searching the book that you love to read first or find an interesting book that will make you want to read? Everybody has difference with their reason of reading a book. Actuary, reading habit must be from earlier. Many people may be love to read, but not a book. It's not fault. Someone will be bored to open the thick book with small words to read. In more, this is the real condition. So do happen probably with this rural and urban hydrology.

Padrões de ocupação do solo e microclimas urbanos na região de clima tropical continental brasileira: correlações e proposta de um indicador

Abstract: This paper is concerned with the urban microclimate in the Brazilian continental tropical climate region. The purpose is to measure correlations between air temperature and some parameters of land occupation in the region, using urban planning variables that can be controlled by municipal regulation, showing distinct urban climatic phenomena for day and night periods. Considering the existing correlations, this research work suggests an indicator relating building density, area covered by trees, and water surface in urban areas, in order to guide the necessary procedures to ameliorate the harsh urban climate in the region.

Spatio-temporal variability of moisture conditions within the Urban Canopy Layer

Abstract: Summary Re-analysed data from an urban climate research project in Munich, Germany, were used to investigate the spatiotemporal variability of moisture conditions (expressed here in vapour pressure VP) within the Urban Canopy Layer UCL. The results, which apply to three main sites and additional subsidiary ones, cover both summer and winter months. The summer month variation of VP is characterised by higher monthly mean values of VP for all three sites, howbeit with considerable inter-site differences. The temporal variability of mean VP values at diurnal time scales is also examined. With respect to the UCL, they reveal different amplitudes and times of occurrence of their extreme values. In addition, results of car traverses performed during clear sky conditions in downtown Munich show a remarkable small-scale spatio-temporal variability of VP. In relation to a sealed downtown site within a courtyard in Munich, a time-dependent urban moisture excess (UME) was formed. A positive correlation between UME and the urban heat island (UHI) could be verified in general. However, it was slightly negative with a very low coefficient of determination in the summer month when the maximum UME preceded the maximum UHI up to 5 hrs. As example for the effects of air moisture on the urban climate within the UCL, the role of VP on a thermal index (physiologically equivalent temperature PET) was investigated. Based on one-year data from another urban climate project in Munich, a positive correlation between PET and VP was found, although the coefficient of determination was somewhat low. However, during a human-biometeorological case study on a typical summer day in the northern downtown of Freiburg, a medium-sized city in southwest Germany, PET and VP showed a negative correlation (possibly because the specific temporal course of VP at the measuring points was mainly influenced by thermally induced turbulence).

The economics of rural areas in the proximity of urban networks: evidence from Flanders

Abstract: Flanders is a densely populated, strongly urbanised region in Northwest Europe, but with still recognisable peri-urban rural territories. These territories have a distinct economic profile that is far from being marginal, but which has a diminishing role for agriculturally related economic activities. From a regionally-based economic approach, the authors argue that these rural areas act as flanking areas for the nearby urban areas, with mutual benefits. Therefore a model representing local economic development in these flanking rural territories can only be relevant if it takes into account this urban-rural partnership, in respect to the territorial identity and cultural features of both these types of areas. The rural-urban partnership should also be an important basis for a rural renewal policy. This policy will undoubtedly contain traditional rural elements stemming from traditional agricultural activities. However, it must also consider economic activities, in particular those of manufacturing and service industries in the countryside. It should also foster those characteristics of the rural environment which can play a decisive role in creating the new opportunities offered by the new localisation factors which are intrinsic to the rise of the new knowledge-based economy.

Sky view factors estimation using a 3d-gis extension

Abstract: The sky view factor indicates the relationship between the visible area of the sky and the area covered by urban structures. A method of sky view factors (SVF) estimation for urban analysis was developed and implemented in a Geographical Information System (GIS). In order to validate this tool, this paper presents a comparison of actual SVF with the results obtained by simulating the SVF in particular areas of a medium sized city with the developed tool. The simulation with this tool pointed out many advantages, such as: reliability; flexibility and ability to predict sky view factors in future scenarios. INTRODUCTION Urban climate and its heat islands phenomena are comprehensively studied nowadays. Yet, many topics on this subject remain important issues to be examined. The urban climate has a high variability and it is generally warmer and less windy than rural climate. It depends on many characteristics such as topography, regional wind speed, urban morphology and many other factors. Considering the urban canopy layer, i.e, the air contained within urban street canyon, its radiation budget depends on thermal characteristics of materials and geometry of the surroundings. Buildings trap energy reducing the urban long wave heat loss and generating the urban heat island. Among the main aspects causing the urban heat island are the physical characteristics and the spatial relationships of urban features. They have a direct influence on the thermal performance of buildings. The less a surface has visibility to the sky, the slower its cooling ability. Therefore, a thermal parameter called sky view factor (SVF) is one of the main heat island causes. Heat islands present their highest intensity in specific times of the day and they are usually greater in nocturnal than in daytime hours. Urban heat islands have significant influence on cities’ energy consumption, however, there are only relatively few works dealing with their relationship. As shown by Santamouris et al. (2001) and Williamson and Erell (2001), there is not only a reduction on heating energy consumption, but also an increase on cooling load of buildings related to the spatial distribution of the urban heat island. Hence, this thermal phenomenon cannot be neglected on thermal simulation. Taking into account those relevant points of the urban thermal environment, a research project named CEU (which in Portuguese stands for “Consumo de Energia Urbano”, or Urban Energy Consumption) is being undertaken at the State University of Sao Paulo in Bauru, Brazil. The CEU Project studies the relevance of urban geometry on the electric energy consumption of medium sized cities, seeking the identification of patterns of urban energy consumption for urban planning proposals. Moreover, the project works in collaboration with another research effort conducted by Silva (2003), which deals with the issue of urban sustainability on medium-sized Brazilian and Portuguese cities (The Urban Sustainability Project). Considering the usual technological limitations of countries in the same stage of development as that of Brazil, CEU Project steps include the development, improvement and application of planning supporting tools, (STModule), as shown in Figure 1. One of the main contributions to the Urban Sustainability Project in this case is the identification of common urban environmental indicators for small and medium-sized cities of both countries. In the present stage of the research, a tool that allows an easy and quick way of calculating and representing sky view factors has been created under the CEU Project framework, as described by Souza et al. (2003). That tool, called 3DSkyView Extension, is mainly an algorithm written in Avenue to work with ArcView GIS 3.2 and its 3D Analyst extension switched on. That tool transforms coordinates of polygons into stereographic and orthographic coordinates to allow sky view factors estimation. As such, it represents an innovation created by the authors, what is here evaluated. As a result of the ST-Module, the 3DSkyView Extension was developed by researchers of the Sao Paulo State University in Bauru, Brazil, and of the University of Minho in Braga, Portugal. After several tests with hypothetical examples, the tool described by Souza et al. (2003) is here applied in a real city scenario. Its potential as a sky view factor simulator is now evaluated under those conditions. Eighth International IBPSA Conference Eindhoven, Netherlands August 11-14, 2003

The impact of urban planning on land use and land cover in Pudong of Shanghai, China

Abstract: Functional zones in cities constitute the most conspicuous components of newly developed urban area, and have been a hot spot for domestic and foreign investors in China, which not only show the expanse of urban space accompanied by the shifts both in landscape (from rural to urban) and land use (from less extensive to extensive), but also display the transformation of regional ecological functions. By using the theories and methods of landscape ecology, the structure of landscape and landscape ecological planning can be analyzed and evaluated for studying the urban functional zones' layout. In 1990, the Central Government of China declared to develop and open up Pudong New Area so as to promote economic development in Shanghai. Benefited from the advantages of Shanghai's location and economy, the government of Pudong New Area has successively built up 7 different functional zones over the past decade according to their functions and strategic goals. Based on the multi-spectral satellite imageries taken in 1990, 1997 and 2000, a landscape ecology analysis was carried out for Pudong New Area of Shanghai, supported by GIS technology. Green space (including croplands) and built-up area are the major factors considered in developing urban landscape. This paper was mainly concerned with the different spatial patterns and dynamic of green space, built-up areas and new buildings in different functional zones, influenced by different functional layouts and development strategies. The rapid urbanization in Pudong New Area resulted in a more homogeneous landscape. Agricultural landscape and suburban landscape were gradually replaced by urban landscape as the degree of urbanization increased. As consequence of urbanization in Pudong, not only built-up patches, but also newly-built patches and green patches merged into one large patch, which should be attributed to the construction policy of extensive green space as the urban development process in Pudong New Area. The shape of green area of 7 functional zones became more and more regular because of the horticultural needs in Shanghai urban planning. Some suggestions were finally made for the study of future urban planning and layout.

An analysis of driving forces of urban land expansion in china

Abstract: This paper analyzes the processes of urban expansion and quantifies its relationship with economic development and population growth during the last 15 years in China, using partial correlation and regression approaches. The results show that the total urban land areas are linearly increased in the last 15 years, and highly related to the growth of GDP and urban population of the whole country, and land requirement for the improvement of urban environment. The more detailed results include that: firstly, during the last 15 years, the land areas of urban built - up area annually go up in the speed of about 850km2; secondly, in the case of controlling for variable of ln( GDP) , the partial correlation coefficient between the areas of urban built - up area and urban population is only 0,0197; on the contrary, in the case of controlling for variable of urban population, the partial correlation coefficient between the land area of urban built - up areas and In( GDP) is 0.6335. So, development of economy can better explain the expansion of urban land use than urban population; thirdly, the economy development is the strongest driving force on the urban land expansion, it can not only directly drive the expansion of urban land use, but also indirectly affect it through urban population and urban environment.

Urban climate and air quality in Trier Germany

Abstract: To conceptualize strategies for regional environmental management in the Trier region, extensive urban meteorological measurements were undertaken. Weather stations from the German Weather Service and the state Pollution Monitoring Network were used as well as a number of our automatic meteorological stations and a mobile platform (instrumented van). The bioclimatic conditions in the city of Trier are affected by the valley of the Moselle River. Both the wind field and the thermal stratification in the urban boundary layer showed local characteristics especially marked in the diurnal variation and monthly mean concentrations of the air pollutants nitrogen and sulfurdioxide (NO x , SO2), ozone (O3) and particle matter (PM10). Catabatic flows from the side valleys partially reduce the urban heat island and increase the ozone concentration in the city in the evening during calm weather conditions. The impact-based air-quality index is mostly determined by a high PM10 concentration. Strategies to reduce air pollutions in the Trier region are discussed.

Energy and indoor climate in urban environments: recent trends:

Abstract: This paper discusses the main issues relating to urban layout and passive cooling. The paper is divided into three main parts. The ” rst part presents the main characteristics of urban climate, especially the temperature distribution in cities, and reports data from the Athens urban climate experiment. The second part investigates and presents the impact of the main parameters de” ning the urban layout to the local climate. In particular the impact of the street layout, albedo, green spaces and building materials are investigated and discussed. Finally, the third part of the report deals with speci” c energy studies relating the energy consumption of buildings for cooling purposes to the urban climate.

Sustainable Development and Urban Growth in the Argentine Pampas Region

Abstract: This article describes the conflict between rural and urban development in the Pampa Ondulada (Rolling Pampas), the ecological region in which the city of Buenos Aires is located, which is one of the world's richest and most productive agricultural areas. It describes the ecological changes brought by urban growth in periurban and rural areas between 1869 and 1991. It also includes an analysis of the social and economical changes during the past decade (1991-2001) and their effect on ecological services. The article ends with a discussion of the lack of planning over the expansion process of the urban agglomeration, including the so-called suburbia settlements of the middle and upper classes and the speculative pricing of land in advance of its development.

Climate and Urban Water Providers in Arizona: An Analysis of Vulnerability Perceptions and Climate Information

Abstract: .................................................................................................................................................. 2

Pioneers of Rural Sprawl in the Rocky Mountain West

Abstract: Urban sprawl has been criticized for its disproportionate impact on the environment. Yet urban areas are in fact less land-intensive than recent rural development patterns. Residential first-movers into such virgin areas may spark waves of ensuing development without incorporating the true social costs of their pioneering. This paper first explores both benefit/cost and game-theoretic frameworks for understanding the private strategies and social implications of such pioneer developments. Evidence regarding regional land-use intensities, path-dependence of rural development, and accumulating social costs of “rural sprawl” are then presented to highlight the relevance of this paper’s theoretical perspective in the Rocky Mountain West. The primary conclusion of the combined theoretical and empirical work is that pioneering development in innovative rural locations is likely relative to the social optimum, suggesting a rationale for public policy.

Evaluation and planning control of the ecosystem fragmentation due to urban development

Abstract: To measure the ecosystem fragmentation phenomena due to urban sprawl, it is possible using indicators that consider some functional characteristics, such as shapes and dimensions of the urban objects (road networks and urbanised areas), and ecological and ethological characteristics of target animal species. On the bases of these parameters we can obtain models for different urban fragmentation scenarios, where each model is related to a range of indicator values. The new framework for the territory, drown by the plan, will be more or less suitable for the movement of the species that live around and will be possible to adjust the impacts of the urban transformation on the ecosystems and natural landscapes, analysing this suitability through biopermeability evaluation. The data and the methods used during the research program that we have inserted in the present paper are relative to study area of the Italian Central Apennines, a mountain place where it is possible to find natural areas and complex eco-mosaics, with species of fauna of international importance, and numerous small and middle urban areas “plunged” in the ecological networks.