Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
A study of thermal effect of urban canopy structure on urban heat island with town energy balance scheme

He Xiaofeng,Jiang Weimei,Liu Hongnian and,

大气科学 , 2008,
Abstract: To study the difference and the reasons of simulating the Urban Heat Island(UHI) with the Town Energy Balance(TEB) scheme and with the SVAT(soil-vegetation-atmosphere transfer) scheme,some ideal numerical experiments are performed with a regional boundary layer model,which is developed by Nanjing University.Results show that because of the great ability of simulating urban heat storage,the TEB scheme is better than the SVAT scheme in simulating the UHI phenomenon.Moreover,the UHI obviously affects the thermal structure of urban boundary layer,that is,there is obvious difference of surface potential temperature profile between urban and rural areas in the morning and the evening.At the same time,urban temperature is higher than rural temperature all through the day.The reaching height of the temperature difference between urban and rural areas in the daytime is higher than that in the nighttime.The anthropogenic heating and building structure play an important role in the UHI.The effect of anthropogenic heating on the UHI in the nighttime is greater than that in the daytime.As far as the turbulence in the daytime over the urban areas is concerned,the effect of buildings is larger than that of the anthropogenic heating.
Surface Heat Balance Analysis of Tainan City on March 6, 2001 Using ASTER and Formosat-2 Data  [PDF]
Soushi Kato,Yasushi Yamaguchi,Cheng-Chien Liu,Chen-Yi Sun
Sensors , 2008, DOI: 10.3390/s8096026
Abstract: The urban heat island phenomenon occurs as a mixed result of anthropogenic heat discharge, decreased vegetation, and increased artificial impervious surfaces. To clarify the contribution of each factor to the urban heat island, it is necessary to evaluate the surface heat balance. Satellite remote sensing data of Tainan City, Taiwan, obtained from Terra ASTER and Formosat-2 were used to estimate surface heat balance in this study. ASTER data is suitable for analyzing heat balance because of the wide spectral range. We used Formosat-2 multispectral data to classify the land surface, which was used to interpolate some surface parameters for estimating heat fluxes. Because of the high spatial resolution of the Formosat-2 image, more roads, open spaces and small vegetation areas could be distinguished from buildings in urban areas; however, misclassifications of land cover in such areas using ASTER data would overestimate the sensible heat flux. On the other hand, the small vegetated areas detected from the Formosat-2 image slightly increased the estimation of latent heat flux. As a result, the storage heat flux derived from Formosat-2 is higher than that derived from ASTER data in most areas. From these results, we can conclude that the higher resolution land coverage map increases accuracy of the heat balance analysis. Storage heat flux occupies about 60 to 80% of the net radiation in most of the artificial surface areas in spite of their usages. Because of the homogeneity of the building roof materials, there is no contrast between the storage heat flux in business and residential areas. In sparsely vegetated urban areas, more heat is stored and latent heat is smaller than that in the forested suburbs. This result implies that density of vegetation has a significant influence in decreasing temperatures.
The Impact of Urban Anthropogenic Heat on Beijing Heat Environment

Tong Hu,Liu Huizhi,Sang Jianguo,Hu Fei,

气候与环境研究 , 2004,
Abstract: Urban anthropogenic heat plays an important role to urban heat island. A heat em ission inventory was carried out for Beijing in winter which includes sources such as m otor vehicles, waste heat from industrial activities and space heating. A urban boundary layer model was used to simulate a case in Beijing in winter. The effect of urban heat island is studied by considering and ignoring urban anthropologic heat.
The Impact of Anthropogenic Heat on Urban Boundary Layer Structure


大气科学 , 2007,
Abstract: The urbanization is a process that the human being changes the local natural surface characteristics widely and dramatically.This process will impact local atmospheric environment greatly.To understand the urbanization's effect on local urban boundary layer will show its great value in urban weather/climate study,urban environmental protection,urban design and construction,urban disaster-prevention,and will help us improve the residential environment and residential quality in urban area.A numerical simulation model is used in this paper to investigate the effect of the inhomogeneity of urban anthropogenic heat source on the exchanges of energy and material between surface and atmospheric system,and its impacts on urban boundary layer structures.To study the anthropogenic heat affecting the urban boundary layer structures,Hangzhou is taken as an example.A new anthropogenic heat source scheme is developed in the regional boundary layer numerical model(RBLM).In this new scheme,the urban anthropogenic heat source is distributed into different model layers.The lower layer heat release is added into the surface energy budget and the upper layer anthropogenic heat release is coupled into the atmosphere energy equations and its vertical distribution is related with the urban building distribution feature,including building height and density and the diurnal change of anthropogenic heat release is included in this scheme.The numerical simulation results show that this scheme can describe the anthropogenic heat release process better than former schemes and the simulated temperatures,wind directions,wind speeds are closer to the observation data.In the former anthropogenic heat release scheme all of the heat is added into the surface,this leads to the increasing of temperature and turbulence energy,and in the daytime this impact will be transported to upper atmosphere due to the strong turbulence and the increase of atmospheric temperature and turbulence is not obvious in lower air layer.The atmospheric instability increases and the boundary layer height increases by 400 m,the vertical speed over urban area is increased and urban heat island density is strengthened.In the nighttime the impact of anthropogenic heat is more obvious than in the daytime without the solar radiation heating.In the cases of the new scheme turbulence energy in lower layers increases by 40% and the atmospheric stability decreases.In general,the simulation results with the new anthropogenic heat release scheme show that the anthropogenic heat affects the urban boundary layer structure more greatly in the nighttime than in the daytime.And this impact is largest in winter,less in spring and autumn and weakest in summer.The reason may depend on that,in the surface energy budget the solar radiation is the main energy source,while anthropogenic heat is an important but not primary source.Compared with the diurnal and seasonal change of solar radiation,the anthropogenic heat release is a

Zhou Shuzhen,

环境科学学报 , 1991,
Abstract: The occurence of urban high temperature in Shanghai was related to regional climate background and the heating role of urban heat island.The essential measures for mitigating the intensity of summer heat island against the high temperature damages were suggested as to decrease the emission of anthropogenic heat and CO2, to use lighter colors for city surface, to increase the coverages of vegetation and water area, and to control the density and formation of buildings.
Detection of the urban heat island in Mexicali, B. C., México and its relationship with land use
Atmósfera , 2007,
Abstract: in this paper the urban heat islands (uhi), both atmospheric and surface, and their relationship with the land use in the city of mexicali, baja california, méxico, were examined by means of direct in situ measurements of air temperature, and the use of noaa's avhrr and ladsat thermal satellite images. the results show the development of a nocturnal urban heat island, whose highest mean value was recorded in autumn (4.5 °c), however during the day-time, in any season of the year, this situation is reversed and the city becomes a cold urban island. the existence of a surface urban heat island (suhi) could be proved when the city was compared with nearby surroundings. within the city, important thermal contrasts can be seen as a topographic map, and then can be related to different urban land use. the discussion is focused to the relationship that exists between the canopy air temperature, the surface temperature, and the atmospheric energy balance near the ground.
A review on the generation, determination and mitigation of Urban Heat Island
RIZWAN Ahmed Memon,DENNIS YC Leung,LIU Chunho,
RIZWAN Ahmed Memon
,DENNIS Y.C. Leung,LIU Chunho

环境科学学报(英文版) , 2008,
Abstract: Urban Heat Island (UHI) is considered as one of the major problems in the 21st century posed to human beings as a result of urbanization and industrialization of human civilization. The large amount of heat generated from urban structures, as they consume and re-radiate solar radiations, and from the anthropogenic heat sources is the main cause of UHI. The two heat sources increase the temperatures of an urban area as compared to its surroundings, which is known as Urban Heat Island Intensity (UHII). The problem is even worse in cities or metropolises with large population and extensive economic activities. The estimated three billion people living in the urban areas in the world are directly exposed to the problem which will be increased significantly in the near future. Due to the severity of the problem, vast research effort has been dedicated and a wide range of literature is available for the subject. The literature available in this area includes the latest research approaches, concepts, methodologies, latest investigation tools and mitigation measures. This study was carried out to review and summarize this research area through an investigation of the most important feature of UHI. It was concluded that the heat re-radiated by the urban structures plays the most important role which should be investigated in details to study urban heating especially the UHI. It was also concluded that the future research should be focused on design and planning parameters for reducing the effects of urban heat island and ultimately live in a better environment.
Anthropogenic heat release in the atmosphere of Belgrade
An?elkovi? Goran 1
Glasnik Srpskog Geografskog Dru?tva , 2002, DOI: 10.2298/gsgd0202055a
Abstract: During last few decades the phenomenon of global warming up of the atmosphere is discovered. It is also concluded that the climate in cities changes, the main result of what is the higher air temperature, the heat island within the places with cold weather. This happens also in Belgrade. There are many reasons for this phenomenon, but the anthropogenic production of energy is considered to be one of the main factors for the rise of temperature. The aim of this work is to define anthropogenic sources of heat in Belgrade and to reckon the quantity of heat they emit as additional sources in relation to the sun.
Characteristics of Urban Heat Island in Enugu During Rainy Season
IC Enete, MO Alabi
Ethiopian Journal of Environmental Studies and Management , 2012,
Abstract: The rainy season UHI characteristics at several sites in Enugu urban were evaluated using paired measurement programme. The aim was to determine the characteristic of urban heat island in the city during rainy season periods. The study was undertaken in Enugu municipality in the months of June – July of 2006 and 2007. The results indicate that UHI at day and night during rainy season were very different. A downtown –centered heat island was observed both day and night. The day time variations were strongly correlated to the amount of tree shading while in the night, city climate was highly correlated to sky-view factors and thermal properties in the city. Maximum UHI was about 32c during the day and hour-to-hour difference was observed at night around (1800hrs to 2300hrs). UHI over Enugu have been analyzed and results reveal some spatial and temporal characteristics. The UHI has been found to occur throughout the day and night during rainy season. Its structure was observed to be greatly influenced by weather, city, metabolism, anthropogenic activities and local geographic features, land-use, land-cover as well as vegetation and population.
Estimating Urban Heat Island Effects on the Temperature Series of Uccle (Brussels, Belgium) Using Remote Sensing Data and a Land Surface Scheme  [PDF]
Rafiq Hamdi
Remote Sensing , 2010, DOI: 10.3390/rs2122773
Abstract: In this letter, the urban heat island effects on the temperature time series of Uccle (Brussels, Belgium) during the summers months 1960–1999 was estimated using both ground-based weather stations and remote sensing imagery, combined with a numerical land surface scheme including state-of-the-art urban parameterization, the Town Energy Balance Scheme. Analysis of urban warming based on remote sensing method reveals that the urban bias on minimum temperature is rising at a higher rate, 2.5 times (2.85 ground-based observed) more, than on maximum temperature, with a linear trend of 0.15 °C (0.19?°C ground-based observed) and 0.06 °C (0.06 °C ground-based observed) per decade respectively. The results based on remote sensing imagery are compatible with estimates of urban warming based on weather stations. Therefore, the technique presented in this work is a useful tool in estimating the urban heat island contamination in long time series, countering the drawbacks of a ground-observational approach.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.