Showing papers on "Urban climate published in 2009"

Thermal infrared remote sensing for urban climate and environmental studies: Methods, applications, and trends

Abstract: Thermal infrared (TIR) remote sensing techniques have been applied in urban climate and environmental studies, mainly for analyzing land surface temperature (LST) patterns and its relationship with surface characteristics, assessing urban heat island (UHI), and relating LSTs with surface energy fluxes to characterize landscape properties, patterns, and processes. This paper examines current practices, problems, and prospects in this particular field of study. The emphasis is placed in the summarization of methods, techniques, and applications of remotely sensed TIR data used in urban studies. In addition, some future research directions are outlined. This literature review suggests that the majority of previous research have focused on LST patterns and their relationships with urban surface biophysical characteristics, especially with vegetation indices and land use/cover types. Less attention has been paid to the derivation of UHI parameters from LST data and to the use of remote sensing techniques to estimate surface energy fluxes. Major recent advances include application of sub-pixel quantitative surface descriptors in examining LST patterns and dynamics, derivation of key UHI parameters based on parametric and non-parametric models, and integration of remotely sensed variables with in situ meteorological data for urban surface energy modeling. More research is needed in order to define better “urban surface” from the remote sensing viewpoint, to examine measurement and modeling scales, and to differentiate modeled and measured fluxes.

Urban Economic Theory: Land Use and City Size

Abstract: This book examines the economic reasons why people choose to live where they live and develops, through analysis of the bid rent function, a unified theory of urban land use and city size. The first part of the book explicates the basic theory of urban land use and optimal city size. Residential location behavior of households is examined in a microeconomic framework and equilibrium and optimal patterns of residential land use are discussed. The corresponding equilibrium and optimal city sizes are studied in a variety of contexts. Part Two extends the classical theories of von Thunen and Alonso with the addition of externality factors such as local public goods, crowding and congestion, and racial prejudice. The rigorous mathematical approach and theoretical treatment of the material make Urban Economic Theory of interest to researchers in urban economics, location theory, urban geography, and urban planning.

Quantifying the influence of land-use and surface characteristics on spatial variability in the urban heat island

Abstract: The urban thermal environment varies not only from its rural surroundings but also within the urban area due to intra-urban differences in land-use and surface characteristics. Understanding the causes of this intra-urban variability is a first step in improving urban planning and development. Toward this end, a method for quantifying causes of spatial variability in the urban heat island has been developed. This paper presents the method as applied to a specific test case of Portland, Oregon. Vehicle temperature traverses were used to determine spatial differences in summertime ~2 m air temperature across the metropolitan area in the afternoon. A tree-structured regression model was used to quantify the land-use and surface characteristics that have the greatest influence on daytime UHI intensity. The most important urban characteristic separating warmer from cooler regions of the Portland metropolitan area was canopy cover. Roadway area density was also an important determinant of local UHI magnitudes. Specifically, the air above major arterial roads was found to be warmer on weekdays than weekends, possibly due to increased anthropogenic activity from the vehicle sector on weekdays. In general, warmer regions of the city were associated with industrial and commercial land-use. The downtown core, whilst warmer than the rural surroundings, was not the warmest part of the Portland metropolitan area. This is thought to be due in large part to local shading effects in the urban canyons.

CITYSIM: Comprehensive Micro-Simulation of Resource Flows for Sustainable Urban Planning

Abstract: In this paper we describe new software “CitySim” that has been conceived to support the more sustainable planning of urban settlements. This first version focuses on simulating buildings’ energy flows, but work is also under way to model energy embodied in materials as well as the flows of water and waste and inter-relationships between these flows; likewise their dependence on the urban climate. We discuss this as well as progress that has been made to optimise urban resource flows using evolutionary algorithms. But this is only part of the picture. It is also important to take into consideration the transportation of goods and people between buildings. To this end we also discuss work that is underway to couple CitySim with a micro-simulation model of urban transportation: MATSim.

Urban Governance for Adaptation: Assessing Climate Change Resilience in Ten Asian Cities

Abstract: Summary Rapidly expanding urban settlements in the developing world face severe climatic risks in light of climate change. Urban populations will increasingly be forced to cope with increased incidents of flooding, air and water pollution, heat stress and vector-borne diseases. This research, undertaken with a set of partner research institutes, examines how to manage climate-related impacts in an urban context by promoting planned and autonomous adaptation in order to by improve resilience in a changing climate. It investigates the linkages between the characteristics of pro-poor good urban governance, climate adaptation and resilience, and poverty and sustainable development concerns. The paper develops an analytical framework by combining governance literature with rapid climate resilience assessments conducted in ten Asian cities. Based on this empirical data, we argue that a number of key characteristics can be identified to assess and build urban resilience to climate change in a way that reduces the vulnerability of the citizens most at risk from climate shocks and stresses. These characteristics form the basis of a climate resilient urban governance assessment framework, and include (1) decentralisation and autonomy, (2) accountability and transparency, (3) responsiveness and flexibility, (4) participation and inclusion and (5) experience and support. This framework can help to assist in the planning, design and implementation of urban climate change resilience-building programmes in the future.

Cities, Climate Change and Urban Heat Island Mitigation: Localising Global Environmental Science:

Abstract: This paper explores how city planners engaged with global climate scientists to devise contextually relevant strategies to address the urban heat island effect—a potentially dangerous heat event expected to increase along with global warming. Drawing original data from the New York City Regional Heat Island Initiative, a collaborative effort between scientists and urban planners, the paper highlights how global climate science is `localised' as researchers and policy-makers struggle to make technically legitimate and politically accountable decisions. The paper argues that the localisation of global science often involves a process of co-production, where technical issues are not divorced from their social setting and a diverse set of stakeholders engage in analytical reviews and the crafting of policy solutions. The paper argues that the co-production framework can contribute to more scientifically legitimate and publicly accountable decision-making related to urban climate change.

Using Watered Landscapes to Manipulate Urban Heat Island Effects: How Much Water Will It Take to Cool Phoenix?

Abstract: Problem: The prospect that urban heat island (UHI) effects and climate change may increase urban temperatures is a problem for cities that actively promote urban redevelopment and higher densities. One possible UHI mitigation strategy is to plant more trees and other irrigated vegetation to prevent daytime heat storage and facilitate nighttime cooling, but this requires water resources that are limited in a desert city like Phoenix. Purpose: We investigated the tradeoffs between water use and nighttime cooling inherent in urban form and land use choices. Methods: We used a Local-Scale Urban Meteorological Parameterization Scheme (LUMPS) model to examine the variation in temperature and evaporation in 10 census tracts in Phoenix's urban core. After validating results with estimates of outdoor water use based on tract-level city water records and satellite imagery, we used the model to simulate the temperature and water use consequences of implementing three different scenarios. Results and conclusions: We ...

Computing continuous sky view factors using 3D urban raster and vector databases: comparison and application to urban climate

Abstract: The use of high resolution 3D urban raster and vector databases in urban climatology is presented. It applies two different methods to the calculation of continuous sky view factors (SVF), compares their values and considers their usefulness and limitations in urban climate studies. It shows and evaluates the relationship between urban geometry, quantified by SVF, and intra-urban nocturnal temperature variations using areal means in the whole urban area of Szeged, a city located in southeast Hungary. Results from the vector and raster models shows similar SVF values (r 2 = 0.9827). The usefulness of using areal means in SVF-temperature relations is confirmed. The vector and the raster approaches to the derivation of areal means of SVF are both shown to be powerful tools to obtain a general picture of the geometrical conditions of an urban environment.

Urban sprawl in Europe

Abstract: Changes in urban forms and development patterns are crucial to understanding the role of cities as engines of growth Urban sprawl is usually defined as the spreading of a city and its suburbs over rural land at the fringe of an urban area Urban planners emphasize the qualitative aspects of sprawl such as the lack of transportation options and pedestrian-friendly neighborhoods Conservationists tend to focus on the actual amount of land that has been urbanized by sprawl Although urban sprawl has been extensively studied in the United States (see, for example, Brueckner 2000, 2001; Glaeser and Kahn 2001, 2004; Nechyba and Walsh 2004), very few empirical studies have been undertaken in Europe Basic reasons for this lack of research are the conceptual divergences in the US and European geographical definitions of cities and the limitations in the availability of actual data for Europe Urban sprawl is one of the most important types of land use changes currently affecting Europe It increasingly creates major impacts on the environment (via surface sealing, emissions by transport, and ecosystem fragmentation), on the social structure of an area (by segregation, lifestyle changes, and neglect of urban centers), and on the economy (via distributed production, land prices, and issues of scale) It is therefore crucial to understand it better

Altered resources, disturbance, and heterogeneity: A framework for comparing urban and non-urban soils

Abstract: We propose a framework of key concepts useful in understanding how urban soils can contribute to general ecological theory. The major factors that can cause urban soils to be different from soils in non-urban ecosystems are identified and related to the familiar state factor approach. We evaluate directly altered resource availability, and the role of stress in mediating resource availability in urban ecosystems. Modified groundwater and stream flow, and atmospheric deposition of nitrogen and base cations are particularly important resource fluxes to soils in urban ecosystems. Disturbance can be conceptualized in the same way in urban as in non-urban ecosystems. However, in addition to biophysical disturbances familiar to ecologists studying wild lands, demographically and socially mediated changes in ecosystem structure must also be considered. These changes include human migration and population structure, institutional shifts, and the effects of human health. Finally, spatial heterogeneity, including fragmentation and differential connectivity, integrates the effects of resources and disturbance, and has an effect on subsequent resource availability and susceptibility to disturbance. Layers of heterogeneity include not only the geomorphic template, but urban climate, biotic composition, buildings and infrastructure, and demographic-social patterns. The complex layering of natural and social factors that constitute urban heterogeneity permit the continuation of important ecological processes, as well as modify ecological fluxes involving soils. We present a modification of the state factor approach as an expanded framework for the study of urban soils. The understanding of urban soils can contribute to general ecological theory by testing the generality of important ecosystem drivers and their linkage with social processes in an under investigated ecosystem type that is increasing in extent and impact worldwide.

Can green infrastructure promote urban sustainability

Abstract: In 2000, a UK government white paper promoted the prospect of an urban renaissance in the UK to be developed through a series of urban renewal initiatives to create better places for living, working and recreation. Eight years on, there continues to be a policy drive promoting better quality environments through integrative design, social inclusion and public participation. However, whether urban renewal can succeed without a progressive integration of multi-functional green spaces into the urban matrix is still uncertain. This paper proposes that green infrastructure can play a pivotal role in urban renaissance by providing a complementary green matrix of spaces that offer multi-level benefits for human populations. Green infrastructure can also be viewed as simultaneously providing natural resource sinks to assist urban climate control, water management and provide important green networks in an increasingly urbanised Britain. Due to the potential of green infrastructure to be ‘retrofitted’ into most en...

Birds and the City: Urban Biodiversity, Land Use, and Socioeconomics

Abstract: We examined bird diversity in relation to land use and socioeconomic indicators in Leipzig, Germany. We used neighborhood diversity (ND) and bivariate correlation to show that the potential to experience biodiversity in a city is associated with population density, household income, unemployment, and urban green space. People living in urban districts with high socioeconomic status experience the highest species richness around their homes, whereas lower social status increases the chance of living in species-poor neighborhoods. High-status districts are located along forests, parks, and rivers that have a high quantity and quality of green space. However, green space in general does not guarantee high bird diversity. We conclude that bird diversity mirrors land use and socioeconomic patterns within the compact European city of Leipzig. Therefore, urban planning should focus on decreasing these patterns and protecting the remaining species-rich green spaces.

Emerging pattern of urbanization and the contribution of migration in urban growth in india

Abstract: As India has embarked upon economic reforms during the 1990s, published data from the 2001 Census provides an opportunity to study the country's urbanization process with reference to regional inequality and to the contribution of the components of urban growth, namely, natural increase, emergence of new towns, and the net contribution of rural to urban migration. India has more than 4000 cities and towns, which comprise 28 per cent of India's population of 1028 million as enumerated in 2001. However, about two-fifths of India's urban population live in only 35 metropolitan cities. The rate of urban population growth slowed down during the 1990s despite the increased rate of rural to urban migration due to a significant decline in natural increase in urban areas. This has led to an observable slowdown in the pace of India's urbanization.

Fire engineering for high-density cities

Abstract: Part I: An Understanding of High Density 1. Understanding Density and High Density 2. Is the High Density the Only Option? 3 The Sustainability of High Density 4. Density and Urban Sustainability : An Exploration of Critical Issues Part II: Climate and High Density Design 5. Climate Changes Brought About By Urban Living 6. Urbanization and City Climate: A Diurnal and Seasonal Perspective 7. Urban Climate in Dense Cities Part III: Environmental Aspects of High Density Design 8. Thermal Comfort Issues and Implications in High Density Cities 9. Urban Environment Diversity and Human Comfort 10. Designing for Urban Ventilation 11. Natural Ventilation in High Density Cities 12. Sound Environment: High vs Low Density Cities 13. Designing for Daylighting 14. Designing for Waste Minimization in High Density Cities 15. Fire Engineering for Density Cities 16. Role of Urban Greeneries in High Density Cities 17. Energy in High Density Cities 18. Environmental Assessment: Shifting Scales Part IV: High Density Spaces and Living 19. The Social and Psychological Issues of High-Density City Space 20. Sustainable Compact City and High Rise Building 21. Micro-climate in Public Housing - an Approach to Environment in Community Development 22. Designing for High Density Living: High rise, High Amenity & High Design

Urbanisation induces early flowering: evidence from Platanus acerifolia and Prunus cerasus.

Abstract: The effect of towns on plant phenology, i.e. advancement of spring development compared with a rural environment, via the urban heat island (UHI) phenomenon, has been shown for many towns in many countries. This work combines experimental and observational methodology to provide a better and deeper view of climatic habitat in an urban context with a view to understanding the relationship between plant development and urban climate on the intra-urban scale (by taking into account town structure). A dense network of 17 meteorological stations was set up in Rennes, France, enabling us to identify and quantify climatic changes associated with the UHI. Meanwhile, phenological observations were made during early spring (March and April) in 2005 on Platanus acerifolia and Prunus cerasus to study the relationship between climatic and phenological data. The results show that there is both a climatic gradient and a developmental gradient corresponding to the type of urbanisation in the town of Rennes. The town influences plant phenology by reducing the diurnal temperature range and by increasing the minimum temperature as one approaches the town centre. The influence of ground cover type (plants or buildings) on development is also shown. The developmental phases of preflowering and flowering are influenced to differing extents by climatic variables. The period during which climatic variables are effective before a given developmental phase varies considerably. The preflowering phases are best correlated with the mean of the minimum air temperature for the 15-day period before the observation, whereas flowering appears to be more dependent on the mean of the daily diurnal temperature range for the 8 days preceding the observation.

Effect of land cover on air temperatures involved in the development of an intra-urban heat island.

Abstract: Mobile traverses were used to conduct air temperature observations to clarify the effect of land cover on ambient air temperatures. The study area was located in a suburb of the Tokyo metropolitan area, Japan. The mobile traverses were conducted at 2 h intervals between 10:00 h on one day and 08:00 h the next day, on selected days from October 2006 to March 2008, for a total of 30 d. We observed an intra-urban heat island (IUHI) throughout the year and determined the diurnal and seasonal variations in this IUHI. The daily maximum intensities of the IUHI under calm and cloudless conditions ranged from 4.0 to 6.9°C during all seasons of the years examined. Such large IUHI intensities are determined by clear boundaries between adjacent land covers, independent of a city's size. The development of an IUHI is related to the features of the land cover, and the causal factors that enhance an IUHI differ between day- and nighttime. In most cases, observed air temper- atures varied significantly according to ambient land cover types, and air temperatures decreased as the amount of vegetated area around the sites increased. These land cover effects were slightly stronger at night than during the day, and they weakened as the amount of cloud cover or the wind speed increased, especially at night.

Evaluating the Temporal and Spatial Urban Expansion Patterns of Guangzhou from 1979 to 2003 by Remote Sensing and GIS Methods

Abstract: China has experienced and is experiencing expeditious urban expansion in the recent decades, especially in the coastal areas and big cities. Rapid urban expansion and dramatic changes of landscape have caused great economic, environmental and social impacts consequently. It is crucial to understand urban temporal, spatial expansion patterns and their related effects. In this paper, urban expansion of Guangzhou, a rapid growing city in south‐east China, from 1979 to 2003 is studied temporally and spatially. Four time ranges including 1979–1990, 1990–1995, 1995–2000 and 2000–2003 are designed and the urban expansion area, expansion rate and the spatial expansion pattern are discussed by using remote sensing data and Geographical Information System (GIS) tool. Two transects are designed along two axes of Guangzhou expansion and the structural of urban expansion patches at different orientations are compared in order to quantitively understand the urban expansion of Guangzhou during the past 24 years. The gra...

Urbanization and Spatial Connectivity in Ethiopia: Urban Growth Analysis Using GIS

Abstract: In comparison to other African countries, Ethiopia has a low urbanization rate. According to the World Bank World Development Report (WDR) 2009, Sub-Sahara Africa is 30% urbanized, whereas Ethiopia is only 10.9% urbanized. Urbanization rates differ according to methodologies and data base utilized: the United Nations classifies Ethiopia as 14.9% urban, while the Central Statistical Agency of Ethiopia reports a 16% urbanization rate. In an effort to standardize and measure Ethiopian urbanization over time, we use the WDR agglomeration index methodology which incorporates a series of GIS data and analyses including: travel time rasters, population density (namely GRUMP and LandScan gridded population), and other nationally collected biophysical and infrastructure variables. We spatially allocate urban versus non-urban areas by creating specific thresholds following two criteria whereby locations are categorized as urban if populations have: a population density greater than 150 people per km2; and are located within 1 hour travel time from a city of at least 50,000 people. Utilizing road and population data from different years between 1984 and 2006, we are able to model growth in urbanization and reductions in remoteness over time. Using the agglomeration index methodology, we find that the overall share of urban population increased from 3.7 percent in 1984 to 14.2 percent in 2007. The results indicate substantial improvements in travel time between urban centers over the past two decades, though a large share of the population still resides more than 10 hours travel time from an urban center.