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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=667877
• 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. ********

城市现在居住着世界一半以上的人口，这些变化导致了独特的城市气候，影响当地的天气、能源需求、城市的宜居性以及污染物和温室气体的排放。城市地表温度是城市气候的关键组成部分，因为它们代表了地表能量预算（地表热量的输入和输出）的解决方案，因此，城市地表温度的准确测量和建模至关重要。了解创造的过程城市表面也是有意改变城市气候的目标，例如，白色或绿色屋顶是试图通过控制表面温度来改变当地气候的类型。城市寻求适应大规模的气候变化，并提供减轻当地热量和使用导致温室气体排放的能源的方法。***热遥感提供了一种有吸引力的方法，用于观测难以进入的复杂城市表面的表面温度然而，这些传感器只能看到一部分。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特性的变化而产生的微尺度温度变化表现为遥感器处的定向变化的辐射温度。因此，城市地区的测量表面温度具有很强的方向变化（各向异性），这构成了重大挑战，因为这意味着此类测量存在偏差，因此限制了此类数据在城市气候研究中的适用性。 **总体目标该提案是为了更好地了解城市热各向异性并开发模型，以便在一定范围内校正城市地区的热各向异性。这项工作的成果对于我们提供代表性城市表面温度的能力非常重要。变量随城市气温、城市居民的热负荷、建筑物的能源使用而变化，为天气预报和污染物扩散模型提供输入，并用于评估城市散热策略（例如冷表面）********。