HJ-1B卫星遥感数据在重庆市城市热环境监测的应用分析

本文以MODIS反演大气透射率,以HJ-1B/CCD分类结果反演地表比辐射率,并基于单窗算法,利用HJ-1B/IRS4数据反演地表温度.在此基础上,提取研究区的热场变异指数来分析重庆热岛空间分布特征,并就NDVI与NDBI对热岛效应的影响进行了分析.其结果如下:1)重庆城市热岛大致位于中梁山、铜锣山之间,呈东北、西南走向分布;2)热岛中心不在市中心,而是集中在大渡口工业园区、江北机场这些能耗大、人口密集区域,热岛强度范围在5?C-10?C之间;3)接近长江、嘉陵江水域的建筑用地密集区域,其热岛效应并不明显;4)NDVI与热岛强度呈负相关关系,NDBI与热岛强度呈现较为明显的正相关关系,二者对热岛都有重要影响,而NDBI的影响更大.因此,利用HJ-1B数据监测城市热环境,能较好地揭示重庆城市热岛空间分布特征,为城市环境监测与改善提供参考.     

南京市热岛效应时空特征的遥感分析

城市热岛效应是城市化对城市气候影响最典型的表现, 不同城市由于其城市化水平、城市性质、规模以及自然条件的不同而具有不同的时空特征。利用高空间分辨率的Landsat TM 和高时间分辨率的MODIS 相结合定量地分析了南京市热岛效应的时空特征, 并探讨了遥感尺度对城市热岛效应时空特征的影响。结果表明: 南京市热岛效应日特征为白天大于夜晚; 季节特征从热岛强度和热岛范围两方面来说明, 热岛强度: 秋季> 夏季> 春季> 冬季, 分布范围: 夏季> 秋季> 春季> 冬季; 空间上存在3 个分布广且连续的强热岛区, 最大的热岛呈组团状分布、第二的呈线状分布、第三的热岛呈带状分布; 不同遥感尺度下观测到的城市热岛效应强度和范围不同。     

喀什市绿地景观格局分析

针对我国西部干旱区特殊经济发展政策的喀什市绿洲景观规划不合理、现状不明确等问题,提出了利用城市绿地景观指数验证现状、指导景观生态规划、调控城市绿地系统的相关建议;以喀什市2009年对地观测卫星(ALOS)影像数据为主要数据源,在RS和GIS技术的支持下提取喀什市主城区绿地信息,利用生态学的原理与方法对城市绿地景观指数与研究区进行了分析。结果表明:研究区内各绿地类型分布不均匀,绿地景观形状较复杂;公共绿地数量较少,分布集中;生产防护林地斑块呈小零散分布;住宅区绿地面积不大,其他绿地面积较大,但对市内景观影响较小。针对主城区绿地的现状分析,文中提出了"加大绿化、改善结构、群落与廊道相结合"的建议。     

基于遥感的长沙市城市热岛效应时空分析

利用TM/ETM+数据,以长沙市为例,反演了地表温度,并针对不同时相的遥感数据,利用城市热岛强度来反映热岛效应强弱的变化。结果表明,长沙市的热岛空间分布与城市建成区的轮廓相吻合。城市热岛的范围随着城市建设、新建开发区以及道路交通网的发展不断增大,且在东南方向为主要增长方向。根据热岛强度鉴别并提取了强热岛区与正常区,发现长沙市强热岛区的面积已经从1993年的13.18km2扩大至2008年的68.16km2。最后,对长沙市热岛未来的发展趋势进行了预测。     

多源参数在晋江城市热岛分析中的差异性

城市热岛遥感监测分析中,不同参数与指标得到的热岛时空分布结果不同。针对过去研究仅利用遥感反演地表温度或亮度温度监测城市热岛现象,以福建省晋江市为研究区,选择2010年与2014年夏季Landsat数据,结合数字高程数据和气象站点实测数据,反演晋江市域内地表温度与近地表气温。在此基础上,利用多源参数计算多种城市热岛监测指标,并对比分析这些指标用于晋江城市热岛研究的差异性。结果表明:1)2014年较2010年的城市热岛范围扩大,区域内热岛比例显著上升,热岛斑块面积增多且热岛等级增强;2)相对于地表温度,近地表气温用于评价城市热岛空间分布更为合理;3)不同热岛监测指标作用不同,热岛强度、归一化热场强度可以在空间上直接表明热岛空间分布及强弱,热岛比例指数则在数值上反映了不同区域热岛现象的发生概率,热岛源汇指数结合地表热参数和土地覆盖类型,反映了土地利用变化对区域内热岛效应加剧或减缓的贡献程度。     

一种基于八分位法的工业热污染区提取方法

针对工业热污染区提取准确率低、误差大及遗漏率高等问题,提出一种基于八分位法的工业热污染区提取方法。即首先基于改进的单通道算法获得地表温度,其次采用八分位法提取高温异常区,通过叠加建筑用地,得到疑似工业热污染区。然后,以彩钢房为判断标准,利用Google Earth影像进一步提取工业热污染区。通过对比分析热岛强度(HI)、改进的箱线图和八分位法3种方法的精度差异,发现潜在热异常是导致结果降低的主要因素。其中,热岛强度和改进的箱线图法均受到人类活动影响,提取的工业热污染区中居民区和商业区所占比例不小于工业区,误判率较高,八分位法提取精度最高,效果更佳,且从一定程度上避免了潜在热异常带来的影响。为验证结果精度,随机选取10%的工业热污染区像素点作为验证点,经Google Earth核实,发现利用八分位法提取的工业热污染区精度均在70%以上,最高可达92%。因此,八分位法提取工业热污染区简单有效,结果准确可靠,能够避免目标区内潜在热异常的影响,能够为环境保护、工业去产能监测提供技术支撑服务。     

基于MODIS 数据的南京市夏季城市热岛分析

城市热岛效应是当前城市环境与气候主要研究内容之一。地表温度与气温之间有紧密的联系, 通过遥感反演地表温度已成为研究城市热岛的有效手段。利用MODIS 数据, 获取地表比辐射率与大气透过率2 个基本参数, 运用劈窗算法反演南京市夏季地表温度。基于不同时相的MODIS数据, 对4 幅南京市地表温度反演图像作对比分析, 较好地显示了南京市城市热岛的空间分布、热岛范围和城市热岛强度, 结果表明南京市夏季热岛问题较为严重。     

基于城镇指数提取城镇用地信息的方法研究

基于TM影像,结合城市用地特点和热辐射信息,提出一个新型的城镇指数(UI=B6×B5/B4),利用UI对南京及其周围地区的城镇用地信息进行了提取,并用混淆矩阵方法对提取的城市用地信息进行了精度评价。研究结果表明,城镇指数提取城镇用地信息是一种有效、可行的方法,而且具有很高的精确度。     

基于压缩数据维的城市建筑用地遥感信息提取

通过压缩数据维的方式，研究城市建筑用地信息准确提取的原理和方法。通过对城市土地利用类型的分析，选取了归一化差异建筑指数、修正归一化差异水体指数和土壤调节植被指数来代表城市建成区的3种最主要地类——建筑用地、水体和植被。通过将ETM 影像原有的7个波段压缩为由它们衍生的这3个采用比值运算构成的指数波段，大大压缩了数据维数、减少了数据的相关度并降低了不同地类的光谱混淆性。因此采用简单的最大似然分类和掩膜处理技术，就可以将城市建筑用地信息提取出来，其精度可达91．2％。     

CBERS-02IRMSS热红外数据及UTAE算法在城市热岛研究中的应用

文中使用城市热异常信息提取算法(urban thermal anomaly extraction,UTAE)提取城市热岛信息.该算法使用不同大小的滑动窗口来探测整幅图像,根据稳健估计的方法设定地表温度高于全部像元以及窗口内像元温度统计均值加标准差的像元为热异常像元,并将滑动窗口的范围设置在3×3至9×9个像元之间,根据像元被记为热岛像元的次数是否为0来区别热岛区与非热岛区,在热岛区域内根据次数的多少来决定热岛强度,具有动态阈值的特点和无偏特性.研究结果表明,在城市热岛范围的提取上,2004年2月13日长沙市热岛面积在27.21—33.98km2之间;在城市热岛强度和尺度效应分析上,宏观尺度的研究应选用较大的窗口来体现城—郊热岛关系以及热岛发展的总体趋势,而小窗口在微观分析城区内热岛的具体分布、与下垫面的关系以及驱动因子方面较有优势.最后,对UTAE算法在中巴地球资源卫星后继星数据上的应用做出了展望.     

Exploring indicators for quantifying surface urban heat islands of European cities with MODIS land surface temperatures

The term urban heat island describes the phenomenon of altered temperatures in urban areas compared to their rural hinterlands. A surface urban heat island encompasses the patterns of land surface temperatures in urban areas. The classical indicator to describe a surface urban heat island is the difference between urban and rural surface temperatures. However, several other indicators for this purpose have been suggested in the literature. In this study, we compared the eleven different indicators for quantifying surface urban heat islands that were most frequently used in recent publications on remote sensing-based urban heat island assessments. The dataset used here consists of 263 European cities with monthly mean temperatures from MODIS data products for July 2002, January 2003 and July 2003. We found that (i) the indicators individually reveal diurnal and seasonal patterns but show rather low correlations over time, and (ii) for single points in time, the different indicators show only weak correlations, although they are supposed to quantify the same phenomenon. Differentiating cities according to thermal climate zones increased the relationships between the indicators. Thus, we can identify temporal aspects and indicator selection as important factors determining the estimation of urban heat islands. We conclude that research should take into account the differences and instabilities of the indicators chosen for quantifying surface urban heat islands and should use several indicators in parallel for describing the surface urban heat island of a city.     

Satellite-derived urban heat islands from three coastal cities and the utilization of such data in urban climatology

Abstract

NOAA AVHRR satellite infra-red data are used to display the surface radiant temperature heat islands of Vancouver, British Columbia, Seattle, Washington, and Los Angeles, California. Heat island intensities are largest in the day-time and in the warm season. Day-time intra-urban thermal patterns are strongly correlated with land-use; industrial areas are warmest and vegetated, riverine or coastal areas are coolest. Nocturnal heat island intensities and the correlation of the surface radiant temperature distribution with land use are less. This is the reverse of the known characteristics of near-surface air temperature heat islands. Several questions relating to the interpretation and limitations of satellite data in heat island analysis and urban climate modelling are addressed.     

Managing heat rejected from air conditioning systems to save energy and improve the microclimates of residential buildings

Simulations are conducted to investigate the influence and improvement potential of air conditioning heat rejection management of residential buildings on microclimate and energy use. The microclimate and building energy use are simulated on a typical high-rise building in Taipei, Taiwan, on a summer night. Heat rejection from the air conditioners is estimated with a building energy program, EnergyPlus, and a computational fluid dynamics (CFD) program, Windperfect, is used to analyze how heat rejection affects the outside thermal environment. Results show that heat rejection from air conditioners worsens the thermal environment below the urban canopy, thus increasing building energy use. Three countermeasure cases of heat rejection management, which consider the type of cooling system and its installation position, are proposed in this study. The average air temperature increase around the buildings caused by heat rejection was analyzed by transferring the simulation results of the building energy program to the CFD model on an hourly basis. Results show that the air temperature next to the building envelope and the air temperature around air conditioners decrease and that there is a reduction in electricity consumption by the air conditioners when a split-type air conditioner is installed on each floor or on every third floor. A reduction in the ambient air temperature below the urban canopy can be obtained by placing a cooling tower on the roof of the building.     

城市不透水面及其与城市热岛的关系研究-以泉州市区为例

利用Landsat TM卫星影像提取了泉州市1989到1996年的城市建成区不透水面,并研究了其与城市热岛之间的关系。根据Ridd(1995)提出的城市建成区不透水面与植被覆盖度有很强的负相关关系的思想,先利用归一化植被指数求出泉州市建成区的植被覆盖度,进而提取了泉州市建成区的不透水面。通过比较所提取的两个时相不透水面信息,可以看出泉州市区不透水面的面积在7年里有了明显的增加,并主要沿研究区东南部扩展。通过将所提取的不透水面信息与利用TM6波段反演的地表温度进行相关分析,可发现二者之间存在着明显的正相关关系。     

使用单窗算法研究北京城区热岛效应

随着全球变暖和城市化进程的加快,大城市城区的热岛效应日益严重。城市下垫面对地表能量交换的影响巨大,引起地表温度分布的不均一性。遥感技术的发展为地表温度的反演提供了可能。近年来人们使用劈窗算法对均一的海面温度的反演很成功,但是受空间分辨率的限制以及陆面的不均一性,陆面温度的反演一直是一个没有解决好的问题。覃志豪提出了一种TM热红外波段单窗算法,可以利用辅助气象资料快速计算出地表温度。本文以北京市城区为研究区,采用LandsetETM第6波段的单窗算法,反演了亮度温度和地表实际温度,分析了城市下垫面情况下NDVI与地表温度的相关关系,并解释了北京城区热岛在空间上的分布及其可能的原因。结果表明:北京市城区热岛效应显著;地表温度与NDVI相关性显著;城区绿地和水体在区域的温度分布中起到重要作用。     

Heat exposure assessment based on individual daily mobility patterns in Dhaka,Bangladesh

Despite a growing body of evidence indicating increasing health impacts from heat exposure secondary to climate change, previous studies have assessed heat exposure based only on the residential locations of individuals. Such assessments may be imprecise as they do not reflect the impact of people's daily mobility patterns. Furthermore, most studies have focused on urban areas in developed countries, whilst relatively little is known about the situation in developing nations, particularly a tropical climate region where heat exposure is severe for residents. As a case study in Dhaka, Bangladesh, we conducted a heat exposure assessment by integrating individual mobility data which was obtained from a questionnaire survey. Estimates of heat exposure were made using remotely sensed land surface temperature data. Population exposures based on residential locations were compared to a dynamic exposure model that incorporated mobility. Especially for people in suburban areas, we found the traditional assessment method based on the static residential model underestimated exposure compared to the dynamic model owing to the fact that some residents migrate into the city center each day where they tend to experience higher temperatures. We found small differences in heat exposure levels between social groups stratified by gender, age, and income based on the dynamic and static models. These results demonstrate that integration of mobility patterns may be important when comparing exposure levels between urban and suburban populations. Our findings may raise issues regarding new remediation measures against urban heat islands, such as reviewing the distribution of health resources or generating a risk map.     

Impacts of tree and building shades on the urban heat island: Combining remote sensing, 3D digital city and spatial regression approaches

The continued increase in average and extreme temperatures around the globe is expected to strike urban communities more harshly because of the urban heat island (UHI). Devising natural and design-based solutions to stem the rising heat has become an important urban planning issue. Recent studies have examined the impacts of 2D/3D urban land-use structures on land surface temperature (LST), but with little attention to the shades cast by 3D objects, such as buildings and trees. It is, however, known that shades are particularly relevant for controlling summertime temperatures. This study examines the role of urban shades created by trees and buildings, focusing on the effects of shade extent and location on LST mitigation. A realistic 3D digital representation of urban and suburban landscapes, combined with detailed 2D land cover information, is developed. Shadows projected on horizontal and vertical surfaces are obtained through GIS analysis, and then quantified as independent variables explaining LST variations over grids of varying sizes with spatial regression models. The estimation results show that the shades on different 3D surfaces, including building rooftops, sun-facing façades, not-sun-facing façades, and on 2D surfaces including roadways, other paved covers, and grass, have cooling effects of varying impact, showing that shades clearly modify the thermal effects of urban built-up surfaces. Tree canopy volume has distinct effects on LST via evapotranspiration. One of the estimated models is used, after validation, to simulate the LST impacts of neighborhood scenarios involving additional greening. The findings illustrate how urban planners can use the proposed methodology to design 3D land-use solutions for effective heat mitigation.     

基于扫描激光测距数据的建筑物三维重建

建筑物的三维信息是重要的基础地理信息,可以应用于城市的规划、管理等方面,而机载激光扫描测距系统在城市建筑物的三维重建方面具有重要的应用价值。针对我国自行研制的机载激光扫描测距数据提出了一套利用稀疏激光测距数据自动提取建筑物三维信息的方法。首先根据测量的激光距离和相应的姿态、位置信息计算出激光采样点的三维位置,进而可以生成城市的数字表面模型(DSM)和城市的数字地面模型(DTM),依据它们能准确地提取出建筑物的轮廓信息,最后根据建筑物具有规则的形状这个特点来对建筑物的轮廓线进行规则化处理而最终恢复建筑物的三维信息。通过对北京城市北部地区的实际处理,说明了该方法的可行性。