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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=684143
• 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. ********

城市现在拥有世界一半以上的人口，它们对地表和大气产生了重要的改变。这些变化导致了独特的城市气候，影响当地天气、能源需求、城市宜居性以及污染物和温室气体向更大规模气候的输出。城市表面温度是城市气候的一个关键组成部分，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，城市表面温度的准确测量和建模对于了解城市气候的形成过程至关重要。城市表面也是有意改变城市气候的目标。例如，白色或绿色屋顶是冷表面类型，试图通过操纵其表面温度来改变当地气候。 随着城市寻求适应大规模气候变化，并提供减轻当地热量和使用导致温室气体排放的能源的手段，此类措施变得越来越重要。***热遥感提供了一种观察复杂地区表面温度的有吸引力的手段交通困难且空间变异性较大的城市表面。然而，这些传感器只能看到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特性的变化而产生的微尺度温度变化表现为远程传感器处的定向变化的辐射温度。因此，城市地区的特点是测量的表面温度具有很强的方向变化（各向异性）。 这提出了重大挑战，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。 ***该提案的总体目标是更好地了解城市热各向异性并开发模型，以便在城市地区的一系列尺度上校正热各向异性。 这项工作的成果对于我们提供具有代表性的城市表面温度的能力非常重要。 这些温度是城市气温、城市居民热负荷、建筑物能源使用的关键变量，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）。 ******