A Study on the surface geometry dependence of urban surface radiation balance

本研究的目的是探讨地表热平衡对城市地表几何的依赖性。为实现上述目的，本研究开发了利用LANDSAT数据推断地表反照率和地表温度、利用热视频连续观测城市模式地表温度、城市区域热平衡数值模拟等技术。通过对LANDSAT数据的分析发现，在城市地区，反照率较低的点往往具有较高的地表温度，反照率较低、地表温度较高的点具有较高的建筑用地比和较低的视空因子。从热视频对城市模型表面温度分布的连续观察中发现，屋顶、峡谷壁和地面的温度不同，这取决于城市表面几何形状。数值模拟结果表明，顶板、峡谷壁和峡谷底板的表面温度与城市地表几何形状和太阳高度有明显的相关性。

The purpose of the present study is to discuss the surface geometry dependence of the surface heat balance in the urban area. In order to achieve the above purpose, the present study developed technics for inferring the surface albedo and temperature form LANDSAT data, for continuously observing the surface temperatures of urban model by the thermal video, and for numerical simulation of heat balance in the urban area.From analyzing LANDSAT data, it was found that, in the urban area, the point with lower albedo tended to have high surface temperature, and the point with lower albedo and higher surface temperature had higher building-land ratio and lower sky view-factor.From continuous observation on surface temperature distribution of the urban model in terms of the thermal video, it was found that the roof, canyon wall and floor have different temperatures each other, which depended on urban surface geometry.From the numerical simulation, it was found that surface temperatures of roof, canyon wall and floor have clear dependence both on urban surface geometry and on solar elevation.