The phenomenon of an urban heat island was investigated by the use of landsatthematic mapper data sets collected over the metropolitan area of washington, dc. Urban heat islands uhis have a significant and negative impact on the urban ecological environment and on human health, and it is imperative to examine factors that lead to uhis. Urban heat islands uhi are significantly warmer urban areas than its surrounding rural areas due to human activities. The increase of land surface temperature caused by. Aug 03, 2018 the urban heat island effect is not a new phenomena, but countries like the uk are more exposed to the threats of extreme heat as summers get longer and hotter. In order to investigate the health effects of the urban heat. This is a significant cost, and given the range of impacts that were not possible to quantify, this estimate could be. Published in 2014 urban heat island uhi is considered as one of the major problems in the 21st century as a consequence of urbanisation and industrialisation of human civilisation. Does urban heat island effect exaggerate global warming trends. The uhi effect has significant consequences for the liveability in our cities, and is the source of a significant number of environmental problems in urban areas yang et al. Pdf seminar on urban heat island effect dechen norbu. The study of vegetation effects on reduction of urban heat island.
The temperature of urban areas can be significantly higher than that of the surrounding rural areas. The temperature difference between the city and surrounding areas is also a function of winds. Local governments face challenges in adapting to urban heat, however, including the complexity of the choices available, limited resources and authority. Elevated global temperatures may thus be compounded by the additional stress resulting from the urban heat island. In the near future it is expected that the global rate of urbanization will increase by 70% of the present world urban population by 2030, as urban agglomerations emerge and population migration from rural to urbansuburban areas. Chow 9 reported the magnitude of the urban heat island effect in shanghai, china. Urban heat island effect as the name suggest city is getting warmer time to time in comparison to rural areas.
The heat island effect is a term used to describe higher air and structure temperatures in an urban setting as opposed to the lower temperatures found in more rural areas. It is recognized as the most evident characteristic of. Heat waves hws are among the most damaging climate extremes to human society. Uhi is most noticeable during the summer and winter. Effects of urban surfaces and white roofs on global and. Uhi effect will definitely influence material flow and energy flow in urban ecological systems, as well as alter. As cities grow and develop, more buildings and people are added. Jan 30, 2006 surrounding areas due to the urban heat island effect, which is defined as an increase in urban air temperature as compared to surrounding suburban and rural temperature. The elevated temperature in urban areas as compared to rural, less developed areas is referred to as the urban heat island effect. Urban heat islands ucar center for science education. The urban heat island effect in the city of toronto. Many urban and suburban areas experience elevated temperatures compared to their outlying rural surroundings. Jul 05, 2015 the urban heat island effect uhi is a phenomenon whereby the concentration of structures and waste heat from human activity most notably air conditioners and internal combustion engines results in a slightly warmer envelope of air over urbanised areas when compared to surrounding rural areas. In developed areas with lots of buildings and people, the effect of albedo can contribute to a phenomenon known as an urban heat island, which is a region whose average temperature is higher than surrounding rural areas.
The urban heat island uhi effect describes a phenomenon in which temperatures in urban areas are markedly higher than those in surrounding areas. The study also produced urban heat island interactive maps, showing the urban heat island effect for each census tract in and around most urban areas throughout the state. Although numerous studies have been conducted in this field, little research has considered seasonal variations in uhis in coastal cities. Compendium of strategies october 2008 describes the causes and impacts of summertime urban heat islands and promotes strategies for lowering temperatures in u. Ndvi, using multiple linear regression, in ipora brazil. Pdf the urban heat island effect, its causes, and mitigation, with. As a result, the largest urbanrural temperature difference, or maximum heat island effect, is often three to five hours after sunset. It provides an overview of heat islands, how they form, and their impacts, and describes key urban heat island reduction strategies in depth. The urban heat island effect is not a new phenomena, but countries like the uk are more exposed to the threats of extreme heat as summers.
Find out what state and local entities across the country are doing to reduce the urban heat island effect. The summer urban heat island uhi effect is a daytime elevation in the outdoor urban air temperature that results in part from the replacement of trees and other vegetation with buildings, roads and other heat absorbing infrastructure. Vini halve team member project support team empri dr. Fractal analysis of satellitedetected urban heat island. For example, the average summer temperature in fresno is about 84 f, and the urban heat island effect averages 4 f, which is a relatively modest increase over a hot background. The urban heat island effect, its causes, and mitigation. Strong winds reduce the temperature contrast by mixing together the city and rural air. Around half of the worlds human population lives in urban areas. The temperature difference is much lower in winter.
The uhi is the most obvious atmospheric modification attributable to urban ization, the most studied of climate effects of cities and an iconic phenomenon of urban. Usually, under the urban heat island phenomenon, the central regions of urban centres. This fact is known as the urban heat island effect. Taking bozhou industrial park as a research case, this article has numerically simulated urban thermal environment in summer based on digital technology, aiming to provide theoretical reference for the future urban planning and spatial arrangement. The temperature difference is usually larger at night than during the day, and is most apparent when winds are weak. Nonetheless, the uhi negatively impacts not only residents of urban related environs, but also humans and their associated ecosystems located far away from cities.
This is the origin of the name of urban heat island. Urban heat island in hong kong department of architecture, chinese university of hong kong page 7 of 24 in asia, numerous studies on the uhi have also been done in some countries. Urban heat islands may be priority areas for public health education and preparedness for extreme heat. Satellite thermal images can be used to determine the location of hot spots in the urban environment as illustrated in the map above. The warming effect of urbanisation has critical impacts on health and wellbeing, as well as human comfort and the local atmosphere grimmond, 2007. Mitigation of the urban heat island effect can be accomplished through the use of green roofs and the use of lightercolored. No, this is a separate phenomenon where cities are 68f warmer than surrounding rural areas. Taking action will produce multiple benefits including decreased energy costs, improved air quality and reduce health risks. Examining seasonal effect of urban heat island in a coastal city.
The properties of urban roofs and pavements, as well as human activity, contribute to the formation of summer no. Usually, under the urban heat island phenomenon, the central regions of urban. Urban heat islands are created in areas like these. The urban heat island and its impact on heat waves and human. Remote sensing of the urban heat island effect across biomes in the continental usa marc l. The surface urban heat island effect is observed as a temperature difference between surfaces such as roofs and tree canopies or open fields and parking lots. If you want to contribute to a cooler, greener and safer place in extreme heat. The temperature increase is attributed to deforestation and the construction materials adopted for city building. High temperature in the city centers than its surroundings known as the urban heat island uhi effect, which is causing discomfort to the urban dwellers in the summer time is gaining much attention around the world because the world is getting urbanized as it advances in technology.
Difference in vegetation cover is the primary cause of the uhi effect. Size and shape of cities aerodynamically, cities have a very different shape than rural areas. The urban heat island effect in the city of toronto request pdf. Pdf the impact of green areas on mitigating urban heat. Oct 20, 2016 in developed areas with lots of buildings and people, the effect of albedo can contribute to a phenomenon known as an urban heat island, which is a region whose average temperature is higher than surrounding rural areas. The urban heat island uhi effect, which refers to higher temperatures in urban areas than in surrounding rural areas, has significant and negative impacts on the urban ecological environment and human health 1,2. Glyphis cicatricosa an indicator for global warming or an. Environmental protection agency epa explains how an urban heat island uhi is created and states that as urban areas develop, changes occur in their landscape.
Heat is created by energy from all the people, cars, buses, and trains in big cities like new york, paris, and london. The summer urban heat island uhi effect is a daytime elevation in the outdoor urban air temperature that results in part from the replacement of trees and other vegetation with buildings, roads and other heatabsorbing infrastructure causes. Efforts in japan to mitigate the urban heat island effect. Urban planning characteristics to mitigate climate change. In arid or subarid climates, both air pollution and. There is a strong annual profile in the magnitude of the urban heat island effect, and most of the monthly variability can be explained by correlating wind speed and sky cover data to temperature differ. This phenomenon is known as urban heat islands uhi allen et al. Mitigating new york citys heat island with urban forestry, living roofs, and light surfaces pdf. An urban heat island study for building and urban design a thesis submitted to the university of manchester for the degree of doctor of philosophy in the faculty of engineering and physical sciences 2011 henry kei wang cheung school of mechanical, aerospace and civil engineering. Londons sizzling heat island is bad news for your sweaty office. By combining the derived spectral albedos and temperatures, surface energy composites of five surface categories were analysed. Satellite thermal images can be used to determine the location of hot spots in the urban environment as.
The urban heat island may also increase cloudiness and precipitation in the city. Simulations of the uhi based on the increase of normalized difference vegetation index. The urban heat island effects can also be reduced by weather phenomona. Higher temperatures attributed to the urban heat island effect increase the likelihood of nox and vocs forming smog, which has serious health consequences. Alterations of surface area, improper urban planning, air pollution, etc. The development of a heat island has regionalscale impacts on energy demand, air quality, and public health. In urban regions, these future heat waves will be exacerbated by the urban heat island effect, and will have the potential to negatively influence the health and welfare of urban residents. In contrast, the average summer temperature in ontario is lower at about 78 f, while the heat island effect is greater, averaging 9 f over background. Londons sizzling heat island is bad news for your sweaty. A lot of research is currently going into understanding the urban microclimate, and into finding ways of designing cities and building to minimise the effect of a changing climate both by reducing the urban heat island, and by finding ways to cool the insides of buildings.
The urban heat island effect action plan will help to create a city more resilient to urban heat and climate change. Economic assessment of the urban heat island effect. Does urban heat island effect exaggerate global warming. Isotherms on a map show an urban area with higher temperatures emerging like a warm island floating on a cooler sea. Tthe he urban heat island urban heat island eeffect and. The uhi effect has important implications for energy consumption, air quality, and. Examining seasonal effect of urban heat island in a. Fractal analysis of satellitedetected urban heat island effect qihao weng abstract surface radiant temperatures derived from landsat tm thermal infrared images of december, 1989, 03 march, 1996, and 29 august 1997 were used to study the urban heat island uhi phenomenon in guangzhou, china.
Moreover, parametric statistical analyses, such as regression and. An urban heat island uhi is an urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. Researchers at nasa goddard study the urban heat island effect using satellite maps that show visible light, land development. Climate change and health adaptation bulletin canada. Linking science to april 2004 urban heat island and climate. Jonathan winfrey, chris castro and zach bamman bsc 4932l. Causes of urban heat island formation urban heat island impacts on energy consumption, environmental quality, and human health resources for further information. It also shows brief information on climate change in bhutan and others. Buildings, roads and other infrastructure replace open land and vegetation. Paper shows how and why city is warmer and its ways of mitigation. Though heat islands may form on any rural or urban area, and at any spatial scale, cities are favoured, since their surfaces are prone to release large quantities of heat. Learn about the five strategies to reduce the heat island effect.
Mar 31, 2010 the effects of vegetative cooling and the urban heat island effect research by. When a huge amount of natural land is replaced by artificial built surface that absorbs incoming solar radiation or heat and reradiate. The main cause of the urban heat island effect is from the. The increasing awareness of the urban heat island uhi effect has raised the attention for monitoring and evaluating the outdoor thermal comfort in cities worldwide. There forms a temperature difference between the cities and the surrounding suburbs because of the effect yamamoto 2006 which causes discomfort to the city dwellers. For urban residents, the urban heat island uhi effect further exacerbates the heat stress resulting from hws. The purpose of this project is to examine exactly how the infrastructure of an urban area contributes to significant temperature increases, to describe the impacts this effect has on these areas, and to determine solutions for this widespread problem. Ozone can inflame the respiratory tract and increase the lungs susceptibility to. Pdf high temperature in the city centers than its surroundings known as the urban heat island uhi effect, which is causing discomfort to the urban. Widespread surface changes can reduce the urban heat island effect, helping residents adapt to urban heat. Other contributing factors to the heat island effect include.
Urban heat island is a major problem associated with rapid urbanisation. Final report on urban planning characteristics to mitigate climate change in context of urban heat island effect iii project duration august 1, 2016 to september 8, 2017 project team teri ms. A systematical study on uhi was carried in singapore 10. Fractal analysis of satellitedetected urban heat island effect. Since it was first recorded by british meteorologist manley in 1958, the uhi effect has become an important topic, and numerous studies have. Wolfea, lahouari bounouaa a hydrospheric and biospheric science laboratory, nasas goddard space flight center, greenbelt, md, 20771, usa b earth resource technology inc. The main source of uhi is the large amount of heat produced from. Urban heat island which is the condition of excess heat in city centers is one of these environmental issues. With fewer trees in cities and large communities solar energy is more readily absorbed into manmade structures, causing higher urban area temperatures. The urban heat island and its impact on heat waves and. An urban heat island, or uhi, is a metropolitan area thats a lot warmer than the rural areas surrounding it.
The effects of vegetative cooling and the urban heat island effect research by. Pdf the urban heat island effect, its causes, and mitigation, with reference to the thermal properties of asphalt concrete find, read and. Interactions between urban heat islands and heat waves. Climate models consistently project that hw frequency, severity, and duration will increase markedly over this century. The process of urban development leads to this phenomenon. Systems sustaina slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Urban heat island uhi effect is a kind of heat accumulation phenomenon within urban area due to urban construction and human activities. Data from the camden area showed that the urban heat island effect is maximized in august. The urban heat island effect uhi is a phenomenon whereby the concentration of structures and waste heat from human activity most notably air conditioners and internal combustion engines results in a slightly warmer envelope of air over urbanised areas when compared to surrounding rural areas.
Dubai which has developed tremendously in the past. Urban planning characteristics to mitigate climate change in. Urban heat island impacts on energy consumption, environmental quality, and human health resources for further information. Linking science to april 2004 urban heat island and. The urban heat island effect and the role of vegetation to.
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