Thermal anisotropy of urban areas

城市地区的热各向异性

• 批准号: RGPIN-2016-05586
• 负责人: Voogt, James
• 金额: $ 2.26万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615788
• 关键词: Thermal; anisotropy; urban; areas

Cities, now home to over half the world’s population, create important modifications to the surface and atmosphere. These changes result in distinct urban climates that affect local weather, the demand for energy, the livability of cities and the export of pollutants and greenhouse gases to larger scale climates. The temperatures of urban surfaces are a key component of urban climate because they represent a solution to the surface energy budget - the inputs and outputs of heat at the surface. Thus, accurate measurement and modeling of urban surface temperatures is critical for understanding the processes that create urban climates. Urban surfaces are also targets for the intentional modification of urban climates. For example, white or green roofs are types of ‘cool’ surfaces that attempt to modify local climates through manipulation of their surface temperature. Such measures are becoming more important as cities seek to adapt to large scale climate change and provide means to mitigate local heat and use of energy that drives greenhouse gas emissions. Thermal remote sensing provides an attractive means of observing surface temperatures over the complex urban surface where access can be difficult and spatial variability is large. However, these sensors view only a portion of the entire three-dimensional urban surface. When the spatial resolution of the sensor is larger than the surface structure, the microscale temperature variations that arise due to surface structure and variability of surface properties are manifest as a directionally varying radiometric temperature at the remote sensor. As a result, urban areas are characterized by strong directional variability (anisotropy) of the measured surface temperature. This poses a significant challenge because it means that such measurements are biased and therefore limits the applicability of such data to the study of urban climates. The overall objective of this proposal is to better understand urban thermal anisotropy and develop models that will allow correction for thermal anisotropy at a range of scales for urban areas. The outcomes of this work are important to our ability to provide representative urban surface temperatures. These temperatures are a key variable to the air temperature of cities, heat loading on urban residents, energy use by buildings, providing input to weather forecast and pollutant dispersion models and for assessing urban heat mitigation strategies such as cool surfaces.

现在是世界以上人口一半以上的城市，为地表和氛围创造了重要的修改。这些变化导致不同的城市气候影响当地的天气，对能源的需求，城市的宜居性以及污染物和温室气体的出口到更大的气候。城市表面的温度是城市气候的关键组成部分，因为它们代表了表面能预算的解决方案 - 表面热量的输入和输出。这是对城市表面温度的准确测量和建模对于理解创造城市气候的过程至关重要。城市表面也是故意修改城市气候的目标。例如，白色或绿色的屋顶是“凉爽”表面的类型，试图通过操纵其表面温度来修改当地气候。随着城市寻求适应大规模的气候变化，并提供减轻局部热量和使用驱动温室气体排放的能量的方法，这种测量变得越来越重要。 热遥远灵敏度提供了一种在复杂的城市表面上观察表面温度的有吸引力的方法，在复杂的城市表面上可能很困难，空间可变性很大。但是，这些传感器仅查看整个三维城市表面的一部分。当传感器的空间分辨率大于表面结构时，由于表面结构和表面性能的可变性而产生的显微镜温度变化被表现为遥感器上的方向变化的辐射温度。结果，城市地区的特征是测得的表面温度的强烈定向变异性（各向异性）。这构成了重大挑战，因为这意味着此类测量是有偏见的，因此限制了此类数据对城市气候研究的适用性。 该提案的总体目的是更好地了解城市热各向异性，并开发模型，以允许在城市地区的一系列尺度上校正热各向异性。这项工作的结果对我们提供代表性城市表面温度的能力很重要。这些温度是城市空气温度，城市居民的热量，建筑物的能源使用，为天气预测和污染物分散剂模型提供投入以及评估城市缓解降温策略（例如凉爽表面）的关键变量。