Observational and analytical studies on influence of urban surface structure on radiation balance components

研究了城市地表结构对地表辐射平衡分量变化的影响。具体而言，本研究旨在利用城市地表障碍物的屏蔽效应，即屏蔽系数和地表温度，来解释城市地表障碍物产生的附加长波辐射。主要研究成果如下：(1)提出了城市及其周边地区夜间长波辐射场的基本概念。(2)利用关东地区不同城市的鱼眼透镜图像，估算了屏幕因子(名称、墙视因子)的水平分布。结果表明，建成区的屏蔽系数约为10-75%。(3)对结构简单的石质桥墩用砂岩的岩面温度进行了热像分析，取得了较好的结果。因此，热示踪测量可以有效地用于研究墙体表面回火…的实际状态在城市峡谷中有更多的典型模式。(4)利用热图像分析方法研究了多户住宅冬季墙面温度的增暖，讨论了房间采暖和太阳辐射对墙面温度增暖的影响。结果表明，太阳辐射对墙体的加热比窗玻璃更有效，房间采暖对窗玻璃的加热比墙体更有效，这两种加热效应所增加的辐射(4-26W/m2)都非常重视来自表面障碍物的附加长波辐射。(5)长波辐射平衡各分量随屏蔽因子的变化几乎呈线性变化。很明显，如果根据热像分析在三种不同材料中分别估计城市表面障碍物的表面温度，则可以从其屏幕效应中充分估计来自城市表面障碍物的额外长波辐射。(6)白天，城市峡谷内的长波附加辐射增加幅度大于夜间，但由于太阳辐射的遮荫效应减少，净辐射减少。街道遮阳树可以缓解所有的辐射成分。较少

Influence due to urban surface structure on the change of radiation balance components in the groundsurface is investigated. In paticular, this study aims at explaining additional longwave radiation from urban surface obstructions by their screen- effects, namelly their screen-factors and surface temperatures based on thermal image analysis. The main results are summarized as follows : (1) The fundamental concept of longwave radiation field at night is proposed in and around urban areas. (2) The horizontal distributions of screen-factor (namelly, wall view-factor) are estimated from a fish-eye lens image in various cities of Kanto region. It is shown that the screen-factor in built-up area is about 10 - 75%. (3)Thermal image analysis is tried on rock-surface temperature of sandstone used for a masonry bridge pier with simple structure, and sufficient results are obtained. Therefore, thermotracer measurement can be applied usefully to investigate the actual states of wall surface temper … More ature pattern in urban canyon. (4) The warming of wall surface temperature in winter is investigated in a maltiple dwelling house by thermal image analysis, and the influences of room heating and solar radiation on its warming are discussed. The results show that solar radiation heats more effectively wall than windowpane and roomheating heats more effectively windowpane than wall, and the increased radiation (4-26W/m2) by the both heating effects are attached great importance to additional longwave radiation from surface obstructions. (5) Every longwave radiation balancecomponent changes almost lineally with the screen-factor. It becomes clear that additional longwave radiation from urban surface obstructions is sufficiently estimated from their screen-effects, if their surface temperatures are estimated separately in three different materials based on thermal image analysis. (6) In the daytimes within urban canyon, additional longwave radiation increases more than at night, but net radiation decreases due to the shade-effective decrease of solar radiation. Street shade trees mitigate all radiation components. Less