共查询到20条相似文献，搜索用时 625 毫秒
1.
Youshui Zhang Inakwu O.A. Odeh Chunfeng Han 《International Journal of Applied Earth Observation and Geoinformation》2009
As more than 50% of the human population are situated in cities of the world, urbanization has become an important contributor to global warming due to remarkable urban heat island (UHI) effect. UHI effect has been linked to the regional climate, environment, and socio-economic development. In this study, Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) imagery, respectively acquired in 1989 and 2001, were utilized to assess urban area thermal characteristics in Fuzhou, the capital city of Fujian province in south-eastern China. As a key indicator for the assessment of urban environments, sub-pixel impervious surface area (ISA) was mapped to quantitatively determine urban land-use extents and urban surface thermal patterns. In order to accurately estimate urban surface types, high-resolution imagery was utilized to generate the proportion of impervious surface areas. Urban thermal characteristics was further analysed by investigating the relationships between the land surface temperature (LST), percent impervious surface area, and two indices, the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built-up Index (NDBI). The results show that correlations between NDVI and LST are rather weak, but there is a strong positive correlation between percent ISA, NDBI and LST. This suggests that percent ISA, combined with LST, and NDBI, can quantitatively describe the spatial distribution and temporal variation of urban thermal patterns and associated land-use/land-cover (LULC) conditions. 相似文献
2.
Ya Ma Yaoqiu Kuang Ningsheng Huang 《International Journal of Applied Earth Observation and Geoinformation》2010
Studies of urbanization and urban thermal environment are now attracting wide interests among scientists all over the world. This study investigated the influences of urbanization on urban thermal environment as well as the relationships of thermal characteristics to other biophysical variables in Guangzhou, China utilizing three dates of Landsat TM/ETM+ images acquired in 1990, 2000, and 2005, respectively. Vegetation abundances and percent impervious surfaces were derived by means of linear spectral mixture model, and a method for effectively enhancing impervious surface has been developed to accurately examine the urban enlargement. As a key parameter for studying urban thermal characteristics, the land surface temperature (LST) was also retrieved from thermal infrared band of each TM/ETM+ dataset. Based on these parameters, the urban expansion, urban heat island effect and the relationships of LSTs to other biophysical parameters were then analyzed. Results indicated that the area ratio of impervious surface in Guangzhou increased significantly, which grew from 20.56% in 1990, to 34.72% in 2000, and further to 41.12% in 2005, however, the intensity of urban heat island was not always enlarged in observed years. In addition, Geostatistical analyses showed that the mean-centre of the impervious surface was moving towards the northwest during 1990–2005. And correlation analyses revealed that, at the pixel-scale, the association of LSTs to other two variables (vegetation abundance and percent impervious surface) was not straightforward, while LSTs possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional-scale, respectively. This study provided an integrated research scheme and the findings can be very useful for urban ecosystem modeling. 相似文献
3.
This study developed an analytical procedure based upon a spectral unmixing model for characterizing and quantifying urban landscape changes in Indianapolis, Indiana, the United States, and for examining the environmental impact of such changes on land surface temperatures (LST). Three dates of Landsat TM/ETM+ images, acquired in 1991, 1995, and 2000, respectively, were utilized to document the historical morphological changes in impervious surface and vegetation coverage and to analyze the relationship between these changes and those occurred in LST. Three fraction endmembers, i.e., impervious surface, green vegetation, and shade, were derived with an unconstrained least-squares solution. A hybrid classification procedure, which combined maximum-likelihood and decision-tree algorithms, was developed to classify the fraction images into land use and land cover classes. Correlation analyses were conducted to investigate the changing relationships of LST with impervious surface and vegetation coverage. Results indicate that multi-temporal fraction images were effective for quantifying the dynamics of urban morphology and for deriving a reliable measurement of environmental variables such as vegetation abundance and impervious surface coverage. Urbanization created an evolved inverse relationship between impervious and vegetation coverage, and brought about new LST patterns because of LST's correlations with both impervious and vegetation coverage. Further researches should be directed to refine spectral mixture modeling by stratification, and by the use of multiple endmembers and hyperspectral imagery. 相似文献
4.
全面掌握城市不透水面变化规律和现状,对于城市化进程研究、城市规划发展和生态文明建设等具有重要的意义。以宁波市为研究区,基于1987-2015年的Landsat影像,利用完全约束最小二乘混合像元分解法实现宁波市不透水面信息提取,结果表明:完全约束最小二乘混合像元分解法避免了不透水面丰度出现负值的情况,提取精度较好;近30年宁波市不透水面扩张显著,不透水面面积增长近5倍,扩张速率和强度在2007-2010年达到最大,并逐渐趋于平稳,2007年以前宁波市城市扩张以三江口片和各区县(市)主城区为主,2007年后则以新区经济发展带扩张为主。 相似文献
5.
Qihao Weng Mohammad Karimi Firozjaei Amir Sedighi Seyed Kazem Alavipanah 《地理信息系统科学与遥感》2019,56(4):576-604
The urban heat island is considered as one of the most important climate change phenomena in urban areas, which can result in remarkable negative effects on flora, concentration of pollutants, air quality, energy and water consumption, human health, ecological and economic impacts, and even on global warming. The variation analysis of the surface urban heat island intensity (SUHII) is important for understanding the effect of urbanization and urban planning. The objective of this study was to present a new strategy based on the Shannon’s entropy and Pearson chi-square statistic to investigate the spatial and temporal variations of the SUHII. In this study, Landsat TM, ETM+, OLI and TIRS images, MODIS products, meteorological data, topographic and population maps of the Babol city, Iran, from 1985 to 2017, and air temperature data recorded by ground recorder devices in 2017 were used. First, Single-Channel algorithm was used to estimate land surface temperature (LST), and the maximum likelihood classifier was employed to classify Landsat images. Then, based on LST maps, surface urban heat island ratio index was employed to calculate the SUHII. Further, several statistical methods, such as the degree-of-freedom, degree-of-sprawl and degree-of-goodness, were used to analyse the SUHII variation along different geographic directions and in various time periods. Finally, correlation between various parameters such as air temperature, SUHII, population variation and degree-of-goodness index values were investigated. The results indicated that the SUHII value increased by 24% in Babol over different time periods. The correlation coefficient yielded 0.82 between the values of the difference between the mean air temperature of the urban and suburbs and the SUHII values for the geographic directions. Furthermore, the correlation coefficient between the population variation and the degree-of-goodness index values reached 0.8. The results suggested that the SUHII variation of Babol city had a high degree-of-freedom, high degree-of-sprawl and negative degree-of-goodness. 相似文献
6.
Area Delineation and Spatial-Temporal Dynamics of Urban Heat Island in Lanzhou City,China Using Remote Sensing Imagery 总被引：2，自引：0，他引：2
Jinghu Pan 《Journal of the Indian Society of Remote Sensing》2016,44(1):111-127
One of the key impacts of rapid urbanization on the environment is the effect of urban heat island (UHI). By using the Landsat TM/ETM+ thermal infrared remote sensing data of 1993, 2001 and 2011 to retrieve the land surface temperature (LST) of Lanzhou City, and by adopting object-oriented fractal net evolution approach (FNEA) to make image segmentation of the LST, the UHI elements were extracted. The G* index spatial aggregation analysis was made to calculate the urban heat island ratio index (URI), and the landscape metrics were used to quantify the changes of the spatial pattern of the UHI from the aspects of quantity, shape and structure. The impervious surface distribution and vegetation coverage were extracted by a constrained linear spectral mixture model to explore the relationships of the impervious surface distribution and vegetation coverage with the UHI. The information of urban built-up area was extracted by using UBI (NDBI-NDVI) index, and the effects of urban expansion on city thermal environment were quantitatively analyzed, with the URI and the LST grade maps built. In recent 20 years, the UHI effect in Lanzhou City was strengthened, with the URI increased by 1.4 times. The urban expansion had a spatiotemporal consistency with the UHI expansion. The patch number and density of the UHI landscape were increased, the patch shape and the whole landscape tended to be complex, the landscape became more fragmented, and the landscape connectivity was decreased. The heat island strength had a negative linear correlation with the urban vegetation coverage, and a positive logarithmic correlation with the urban impervious surface coverage. 相似文献
7.
Land cover and land use change (LCLUC) is a global phenomenon, and LCLUC in urbanizing regions has substantial impacts on humans and their environments. In this paper, a semi-automatic approach to identifying the type and starting time of urbanization was developed and tested based on dense time series of Vegetation-Impervious-Soil (V-I-S) maps derived from Landsat surface reflectance imagery. The accuracy of modeled V-I-S fractions and the estimated time of initial change in impervious cover were assessed. North Taiwan, one of the regions of the island of Taiwan that experienced the greatest urban LCLUC, was chosen as a test area, and the study period is 1990 to 2015, a period of substantial urbanization. In total, 295 dates of Landsat imagery were used to create 295 V-I-S fraction maps that were used to construct fractional cover time series for each pixel. Root Mean Square Error (RMSE)s for the modeled Vegetation, Impervious, and Soil were 25 %, 22 %, 24 % respectively. The time of Urban Expansion is estimated by logistic regression applied to Impervious cover time series, while the time of change for Urban Renewal is determined by the period of brief Soil exposure. The identified location and estimated time for newly urbanized lands were generally accurate, with 80% of Urban Expansion estimated within ±2.4 years. However, the accuracy of identified Urban Renewal was relatively low. Our approach to identifying Urban Expansion with dense time series of Landsat imagery is shown to be reliable, while Urban Renewal identification is not. 相似文献
8.
热岛效应是城市化进程中产生的特有环境问题。基于Landsat TM/ETM+（1989、2001、2007、2013年）遥感影像完成哈尔滨地面亮温定量反演、标准化和等级划分等处理,并分析城市热岛空间分布特征和时空演变规律。基于地学信息图谱理论,定量分析24 a间热岛效应图谱信息变化特征,探究城市热岛格局的时空演变进程和形成机制,揭示城市化进程与热岛效应之间的响应关系。结果表明,随着哈尔滨城市化进程加速,4级热岛效应呈递增趋势,面积比例分别为4.36%、5.69%、6.29%和7.12%,主要分布在道外区和铁路沿线地带;植被和水体区域的地面温度较低,其边缘温度更低;反复变化型面积最大,后期变化型面积最小,面积比例分别为33.30%和7.30%。地学信息图谱分析可为城市热岛效应随城市化演变趋势提供准确、丰富的信息,对全面分析城市热岛的形成和发展具有重要的意义。 相似文献
9.
10.
Yongming Xu Zhihao Qin Hongxiu Wan 《Journal of the Indian Society of Remote Sensing》2010,38(4):654-663
One of the significant environmental consequences of urbanization is the urban heat island (UHI). In this paper, Landsat TM images of 1986 and 2004 were utilized to study the spatial and temporal variations of heat island and their relationships with land cover changes in Suzhou, a Chinese city which experienced rapid urbanization in past decades. Land cover classifications were derived to quantify urban expansions and brightness temperatures were computed from the TM thermal data to express the urban thermal environment. The spatial distributions of surface temperature indicated that heat islands had been largely broadened and showed good agreements with urban expansion. Temperature statistics of main land cover types showed that built-up and bare land had higher surface temperatures than natural land covers, implying the warming effect caused by the urbanization with natural landscape being replaced by urban areas. In addition, the spatial detail distributions of surface temperature were compared with the distribution of land cover by means of GIS buffer analysis. Results show remarkable show good correspondence between heat island variations with urban area expansions. 相似文献
11.
The Urban Heat Island (UHI) phenomenon, a typical characteristic on urban landscapes, has been recognised as a key driver to the transformation of local climate. Reliable retrieval of urban and intra-urban thermal characteristics using satellite thermal data depends on accurate removal of the effects of atmospheric attenuations, angular and land surface emissivity. Several techniques have been proposed to retrieve land surface temperature (LST) from coarse resolution sensors. Medium spatial resolution sensors like the Advanced Space-borne Thermal Emission and Reflection Radiometer and the Landsat series offer a viable option for assessing LST within urban landscapes. This paper reviews the theoretical background of LST estimates from the thermal infrared part of the electromagnetic spectrum, LST retrieval algorithms applicable to each of the commonly used medium-resolution sensors and required variables for each algorithm. The paper also highlights LST validation techniques and concludes by stipulating the requirements for LST temporal and spatial configuration. 相似文献
12.
不透水面是衡量城市生态环境的重要指标，针对平原河网区不透水面与水体、裸土等地物较难区分的问题，以苏北里下河平原快速城镇化区为研究对象，利用多时相Landsat影像为数据源，基于像元光谱特征及其季节性变化分析，构建了基于时序NDWI、NDVI和NDBI的决策树模型，并利用GIS空间分析技术对不透水面的时空变化特征进行了分析。结果表明：多时相光谱信息可有效改善水体、裸土和稀疏植被等像元与不透水面的混分，2005年和2016年的不透水面分类总体精度和Kappa系数均在0.85以上，合理反映了不透水面以向东和向南扩张为主的趋势特征，年均扩张速度约为6.7 km2。研究成果为该区城镇化下的生态环境效应研究提供数据基础，同时可为其他平原河网区不透水面信息提供借鉴和参考。 相似文献
13.
以2001年7月11日LandsatETM7影像和2009年7月16日TM影像为数据源,基于V-I-S理论模型,采用归一化光谱分解模型提取了乌鲁木齐市区范围内2个时段的植被、土壤、不透水层3个连续地表参数分量。通过对不透水层不同阈值的划分,提取了2时段的乌鲁木齐市城市发展的空间信息,结果较为满意;通过空间叠加计算方式获取了8年来乌鲁木齐市城市化发展的空间信息和主要拓展方向。结果表明,乌鲁木齐城市化发展速度较快,特别是北扩趋势显著。 相似文献
14.
Yitong Jiang 《地理信息系统科学与遥感》2017,54(1):95-117
Surface moisture is important to link land surface temperature (LST) to people’s thermal comfort. In urban areas, the surface roughness from buildings and urban trees impacts wind speed, and consequently surface moisture. To find the role of surface roughness in surface moisture estimation, we developed methods to estimate daily and hourly evapotranspiration (ET) and soil moisture, based on a case study of Indianapolis, Indiana, USA. In order to capture the spatial and temporal variations of LST, hourly and daily LST was produced by downscaling techniques. Given the heterogeneity in urban areas, fractions of vegetation, soil, and impervious surfaces were calculated. To describe the urban morphology, surface roughness parameters were calculated from digital elevation model (DEM), digital surface model (DSM), and Terrestrial Light Detection and Ranging (LiDAR). Two source energy balance (TSEB) model was employed to generate ET, and the temperature vegetation index (TVX) method was used to calculate soil moisture. Stable hourly soil moisture fluctuated from 15% to 20%, and daily soil moisture increased due to precipitation and decreased due to seasonal temperature change. ET over soil, vegetation, and impervious surface in the urban areas yielded different patterns in response to precipitation. The surface roughness from high-rise has bigger influence on ET in central urban areas. 相似文献
15.
武汉城镇化与热岛效应的定量研究 总被引：1，自引：0，他引：1
针对目前城市化进程加快对城市增温和城市热岛效应的促进作用尚不十分明确的问题,提出基于遥感技术的城镇化与热岛效应数量关系的构建。结果表明,1987-2013年间,武汉市中城镇化水平(50%~80%ISA)面积增加了14.5倍,高城镇化水平(80%~100%ISA)面积增加了2.8倍,城镇化范围沿着武汉市主城区和主要干道不断扩张;不透水面值与地表温度表现出明显正相关,不透水面值平均增加1%,可使地表温度增温0.06℃~0.19℃,城镇化水平对武汉城市热岛效应作用明显。研究结果为探讨城市热岛效应的缓解对策提供了基础,对合理规划和管理城市化意义重大。 相似文献
16.
城市不透水表面遥感估算研究 总被引：4，自引：0，他引：4
作为城市化水平的关键指示因子，不透水表面已经被广泛应用在城市生态环境评估中。利用TM影像，采用附有限制条件的线性光谱混合模型对北京城区的不透水表面分布进行空间分析。通过高反照率、低反照率、植被及土壤4类光谱端元的线性组合表征城市土地覆盖类型，综合剔除噪声影响后的高、低反照率分量，估算北京城区不透水表面分布。研究结果表明：利用附有限制条件的线性光谱分解得到的RMS平均值为0．003428。其不透水表面分布结果与同期spot-5对比验证，R2为0．932，均方根误差为0．086，结果令人满意。 相似文献
17.
选取中等城市——四川省绵阳市为研究对象,以2000年(代表秋季)、2001年(代表春季)TM/ETM+遥感影像为数据源。在基于影像算法反演地表温度的基础上,对研究区春、秋两季热场剖面、建成区范围内热力景观斑块和城市热岛效应进行研究。结果表明:(1)无论春季还是秋季,地表温度高低与下垫面性质具有较大相关性,水体和植被覆盖较好的区域呈现低温,而水泥、沥青等不透水面温度较高;(2)秋季相对春季而言,温度相对较高的热力景观类型面积减少,而温度较低的热力景观类型面积增加。分析热力景观异质性指数发现,优势度指数值春季大于秋季,说明春季存在较明显的优势斑块;(3)运用城乡平均温度对比法和热岛面积指数法,计算春季热岛强度值为1.77℃,秋季热岛强度值为0.78℃,由此说明,在该时段内春季的城市热岛效应强于秋季。 相似文献
18.
本文选取中等城市绵阳为研究对象,以2000年、2007年TM/ETM+遥感影像为数据源,首先应用COST模型完成大气校正;然后采用Artis等提出的算法进行地表温度反演,并利用均值标准差法进行温度等级划分,获得绵阳市地表温度分布图和温度等级分布图。结果表明:①2000-2007年热岛区与建成区在空间发展趋势上基本一致,其中2000年热岛区面积为11.49 km2,到2007年增加为43.12 km2,热岛区面积所占比例增加36.36%;②7年间温度等级升高的区域面积为56.09km2,占建成区总面积的64.47%,其中从温度较低区转化为热岛区比例占42.40%。 相似文献
19.
泰安市区不透水面覆盖度遥感估算研究 总被引：2，自引：1，他引：1
区域不透水面覆盖度是该区域城镇化程度、生态环境状况的重要指示因子。针对传统线性混合像元分解丰度图经常出现负值或者大于1的情况,采用完全约束最小二乘混合像元分解方法,利用泰安市市区Landsat8 OLI遥感影像提取了其不透水面分布状况,运用高分辨率遥感影像随机采样进行了精度检验,并对该区域不透水面空间特征进行了分析。结果表明:该文方法对泰安市市区不透水面分布提取的精度较高;植被、水体、高和低反照率不透水面4种光谱端元的线性组合,可以较好地模拟OLI影像的波谱特征;高、低反照率不透水面两种光谱端元可以很好地表达泰安市市区不透水面信息。 相似文献
20.
北京地区陆表温度空间分布特征 总被引：2，自引：0，他引：2
利用北京地区1999年的Landsat7/ETM+热红外波段数据反演陆表温度,用热岛比率指数表征陆表温度的空间分布差异。通过计算北京市城区及辖区共15个区、五环路内各环线间区域、以及以故宫为中心的8个方向剖线的缓冲区的热岛比率指数,定量分析其陆表温度空间分布特征。结果表明:北京地区陆表温度空间分布存在明显的差异。总体上城区整体处于次高温区,局部表现为高温区,并且在城区以外的辖区出现了多热岛中心分布的特征;对城区及辖区热岛比率指数分析发现,热岛比率指数最大的区域并不是城区,而是顺义区,为0.6210,其平均地表温度在各区域中也最高,为38.08℃。城区大部分处于次高温区中,热岛比率指数为0.6118,平均陆表温度为37.18℃;五环内区域的平均陆表温度为36.97℃,五环以外区域的平均陆表温度35.18℃;对于五环内各环线间的区域,四环至三环间的区域热岛比率指数最高,为0.6327,其平均地表温度为37.48℃;就8个方向剖线的缓冲区分析总体来看,东向和南向热岛比率指数较高,而西向和北向较低。 相似文献