专业外语.docx

1、专业外语Thermal remote sensing of urban climates城市气候热遥感J.A. Voogt a,*,T.R.Oke ba Department of Geography, University of Western Ontario, London, ON, Canada N6A 5C2b Atmospheric Science Program, Department of Geography, University of British Columbia, Vancouver, BC, Canada V6T 1Z2Received 8 April 2002; r

2、eceived in revised form 20 September 2002; accepted 28 December 2002Abstract：摘要：Thermal remote sensing has been used over urban areas to assess the urban heat island, to perform land cover classifications and as input for models of urban surface atmosphere exchange. Here, we review the use of therma

3、l remote sensing in the study of urban climates, focusing primarily on the urban heat island effect and progress made towards answering the methodological questions posed by Roth et al. International Journal of Remote Sensing 10 (1989) 1699. The review demonstrates that while some progress has been

4、made, the thermal remote sensing of urban areas has been slow to advance beyond qualitative description of thermal patterns and simple correlations. Part of the difficulty lies in the tendency to use qualitatively based land use data to describe the urban surface rather than the use of more fundamen

5、tal surface descriptors. Advances in the application of thermal remote sensing to natural and agricultural surfaces suggest insight into possible methods to advance techniques and capabilities over urban areas. Improvements in the spatial and spectral resolution of current and next-generation satell

6、ite-based sensors, in more detailed surface representations of urban surfaces and in the availability of low cost, high resolution portable thermal scanners are expected to allow progress in the application of urban thermal remote sensing to the study of the climate of urban areas.2003 Elsevier Inc.

7、 All rights reserved.热遥感已用于城市地区，用以对城市热岛进行评估，对土地覆盖进行分类，并进行城市地表大气交换模型的输入。在这里，我们回顾了热遥感技术在城市气候研究中的应用，重点初步研究了城市热岛效应，并在回答Roth等人提出的分类法问题等方面取得了进步International Journal of Remote Sensing 10 (1989) 1699。过去的发展证明虽然已经取得了一些进展，城市区域热遥感已缓慢超越热模式的定性描述和简单相关性原则。部分困难在于倾向于使用基础的土地数据来描述城市地表，而不是表面的更基本的定性描述。热遥感在自然和农业表面应用取得的进步证

8、明可以在城市区域运用可能的方法以推进其技术和能力。当前和下一代卫星传感器在空间分辨率和光谱分辨率方面的改进，在城市表面更细微的表现和更低的成本，以及高分辨率便携式热扫描仪可使城市热遥感技术在城市气候的研究方面取得进展。Keywords: Remote sensing; Urban climates; Rural关键字：遥感、城市气候、农村的1. Introduction1. 简介The surface temperature is of prime importance to the study of urban climatology. It modulates the air temper

9、ature of the lowest layers of the urban atmosphere, is central to the energy balance of the surface, helps to determine the internal climates of buildings and affects the energy exchanges that affect the comfort of city dwellers. Surface and atmospheric modifications due to urbanization generally le

10、ad to a modified thermal climate that is warmer than the surrounding non-urbanized areas, particularly at night. This phenomenon is the urban heat island (UHI). UHIs have long been studied by ground-based observations taken from fixed thermometer networks or by traverses with thermometers mounted on

11、 vehicles. With the advent of thermal remote sensing technology, remote observation of UHIs became possible using satellite and aircraft platforms and has provided new avenues for the observation of UHIs and the study of their causation through the combination of thermal remote sensing and urban mic

12、rometeorology. In some ways, it has also complicated definitions of urban heat islands and interpretations of the resulting observations. The present review is prompted, in part, by the appearance of new satellite-based sensors and the increasingly wide- spread use of infrared sensors in the study o

13、f surface climates in general. This has also increased opportunities for studying the UHI and urban-modified climates more generally.表面温度是城市气候学研究最重要的因素。它调节城市大气最下层的空气温度，最重要的是保持表面能量平衡，有助于确定建筑物内部的气候，影响能量交换，这一切都与城市居民生活的舒适性有关。城市表面和大气的改变会产生热气候，致使其比周围的非城市化地区温暖，尤其是在晚上。这种现象被称为城市热岛（UHI）。以固定网络为基础的地面观测或车载温度计早已研

14、究了UHIs。随着遥感技术的出现，UHIs可以利用卫星和飞机平台进行远程观测，通过热遥感和城市微气象学研究的结合来观测热岛及其因果关系。在某些方面，它也复杂的定义了UHIs和观测结果的解释。目前的检测速度很快，部分原因是由于以新卫星为平台的传感器的出现和红外传感器在表面气候研究的日益广泛的使用。这也增加了UHIs研究的机会和城市气候分类的普遍性。We begin by emphasizing the importance of using proper definitions in the application of thermal remote sensing to the study o

15、f urban climates. This is followed by a brief survey of literature appearing since Roth, Oke, and Emery (1989) that highlights several recurrent themes. It then reexamines the methodological questions raised by Roth et al. (1989) concerning problems involved in the application of remotely sensed the

16、rmal imagery to the study of urban climates. It makes comment on the progress made on these points by research conducted over urban and other surfaces. The review concludes by commenting on future prospects for progress in answering these questions. 我们首先强调合适的定义在城市气候热遥感应用方面的重要性。自Roth、Oke以及Emery（1989）

17、提出了几个经常出现的主题就又有了简明的文献调查。然后，重新审查了Roth等人（1989）在城市气候热遥感应用方面提出的方法及问题，它使通过研究这些关于城市及其它表面所取得的进展发表评论，并用此在解决问题时取得进步。1.1 Thermal remote sensing of urban surfaces: definitions1.1 城市表面热遥感的定义Proper definition of remotely sensed variables is important in order to understand precisely the information content of re

18、motely sensed quantities and how they relate to actual surface properties. Thermal remote sensing of urban surface temperatures is a special case of observing land surface temperature which varies in response to the surface energy balance. The resultant surface temperature incorporates the effects o

19、f surface radiative and thermodynamic properties, including surface moisture, thermal admittance and surface emissivity, the radiative input at the surface from the sun and atmosphere, and the effects of the nearsurface atmosphere and its relation to turbulent transfer from the surface.为了正确的了解遥感信息量及

20、它们与表面性能的关系，正确定义遥感变量是非常重要的。城市表面温度热遥感是观测地表温度以及应对不同的地表能量平衡的特殊情况。地表温度受地表辐射和热力学性质的影响，包括表面的水分，热传导和表面辐射率，太阳和大气辐射到地面的能量，近地面大气的影响以及它和表面湍流的关系。Becker and Li (1995), Norman and Becker (1995), Norman, Divakarla, and Goel (1995) and Prata, Caselles, Coll, and Sobrino (1995) have carefully examined the definitions

21、 associated with thermal remote sensing of land surfaces, and the reader is referred to them for details. Here, we use the term directional brightness temperature to describe the temperature derived from the inversion of Plancks law for a thermal sensor operating in a given waveband. Directional bri

22、ghtness temperatures relate the detector-received radiance to a temperature, without consideration of any processes influencing the received radiation along the path from the surface through the atmosphere to the sensor (with appropriate sensor offsets and gains applied). Directional radiometric tem

23、peratures are those that have been corrected for atmospheric transmission and surface emissivity effects for a particular sensor-viewing angle. These definitions apply most strictly to a homogeneous surface, but techniques are available to extend their use to heterogeneous surfaces (Becker & Li, 199

24、5; Norman & Becker, 1995).Becker and Li (1995), Norman and Becker (1995), Norman, Divakarla, and Goel (1995) and Prata, Caselles, Coll, and Sobrino (1995)已经仔细审查了与地表热遥感有关的定义，读者用它们作为细节方面的参考。在这里，我们使用术语方向亮度温度来描述从普朗克定律分离得到的给定工作波段的温度传感器。设计定向亮度温度探测器接收的辐射温度，不受任何影响，通过传感器接收到从表面到大气辐射的过程（通过合适的传感器将其抵消和增加）。定向无线电度

25、量温度是那些已经大气传输和特定传感器视角校正表面发射率的方法。这些定义适用于严格均匀的表面，但技术可以延伸其使用异构表面(Becker & Li, 1995; Norman & Becker, 1995)。Heat islands can be defined for different layers of the urban atmosphere, and for various surfaces and even the subsurface (Oke, 1995; Voogt & Oke, 1997). It is important to distinguish between the

26、se different heat islands as their underlying mechanisms are different (Oke, 1982; Roth et al.,1989). Unless otherwise indicated, an urban heat island refers to the excess warmth of the urban atmosphere compared to the non-urbanized surroundings. Atmospheric heat islands are best expressed under cal

27、m and clear conditions at night when radiative cooling differences are maximized between urban and surrounding rural locations (e.g. Fig. 1a).热岛可以被定义为城市大气中的不同层次，以及各种表面，甚至地下(Oke, 1995; Voogt & Oke,1997)。区分这些热岛的不同时重要的，因为它们的基本机制是不同的(Oke, 1982; Roth et al.,1989)。除非另有说明，城市热岛是指城市地区与非城市地区相比大气温度较高。大气热岛能清楚的表

28、达在夜间寒冷情况下城市和边远区域的辐射冷却的不同。(e.g. Fig. 1a)。Fig. 1. Heat island transect across Vancouver BC for (a) nighttime (YD 238 1992; 9 h after sunset) and (b) daytime (YD 237 1992; 2 h following solar noon) showing canopy level air temperature and remotely sensed surface temperature with various levels of corre

29、ction applied. The plotted results represent values normalized to a single time. Symbols are reduced to every third point to improve readability. The automobile traverse passed through a tunnel ( 4 km) and over bridges ( 15 and 25 km) along the route. Panel (c) is the sky view factor for sites along

30、 the traverse route as determined from digital fish-eye lens photographs, NDVI derived from AVHRR imagery during the traverse, emissivities applied during the conversion to obtain directional radiometric temperatures, and wall and vegetation area weightings applied to take into account unseen surfac

31、es from the nadir viewing position.Atmospheric heat islands may be defined for the urban canopy layer (UCL), that layer of the urban atmosphere extending upwards from the surface to approximately mean building height, and the urban boundary layer (UBL), that layer above the UCL that is influenced by

32、 the underlying urban surface. Canopy layer UHI are typically detected by in situ sensors at standard (screen-level) meteorological height or from traverses of vehicle-mounted sensors, such as that shown in Fig. 2. UBL heat island observations are made from more specialized sensor platforms such as tall towers, radiosonde or tethered balloon flights, or from aircraft-mounted instruments. These direct, in situ measurements require radiation shielding and aspiration to give representative measurements and their setting relative to surrounding features is important.大气热岛可以被定义为城市最顶层（UCL）的即