Heat balance analysis in urban areas by high-resolution satellite remote sensing

城市热岛效应不仅是人类热排放的结果，也是地表土地覆被变化引起的热平衡变化的结果。这项研究开发了一种新的分析方法，使我们能够区分这两种影响并对其进行定量评估。修改了一个热平衡模型，以便能够区分两个部分：人类热排放产生的人类学显热，以及太阳和大气辐射产生的自然感热。该模式分别计算了地表热通量分量、净辐射、地面热通量、感热通量和潜热通量。感热通量与地面和大气温度之差成正比。我们假设，人类学上的感热可以用实际测量的感热通量和模拟的太阳辐射感热通量之间的差值给出。利用该模型对名古屋的热平衡进行了分析。模型的输入是ASTER和Landsat/ETM+等高分辨率卫星遥感数据的参数，以及温度、太阳辐射和风速等气象数据。因此，我们可以得到反映季节空调需求和太阳辐射模式的合理的热平衡变化。此外，城市地区的感热通量始终高于其他土地覆盖类型。因此，我们得出的结论是，我们的新方法允许我们估计城市地区的人类学热排放，并对研究城市地区的热岛效应非常有用。

The heat island effect in urban areas is caused by not only anthropologic heat discharge but also heat balance changes as a result of surface land-cover changes. This study developed a new analysis method that enables us to discriminate these two effects and to evaluate them quantitatively. A heat balance model was modified to be able to distinguish the two components ; the anthropologic sensible heat due to anthropologic heat discharge, and the natural sensible heat due to solar and atmospheric radiation. The model calculates surface heat flux components ; net radiation, ground heat flux, sensible heat flux, and latent heat flux, respectively. The sensible heat flux is proportional to a difference of the surface and atmosphere temperatures. We assumed that the anthropologic sensible heat can be given as a difference between the actually measured sensible heat flux and the modeled sensible heat flux from the solar radiation. By using this model, the heat balance in Nagoya was analyzed. Model inputs were of the parameters from high-resolution satellite remote sensing data such as ASTER and Landsat/ETM+, and the meteorological data such as temperature, solar radiation, and wind speed. As a result, we could obtain reasonable heat balance changes that reflect seasonal air-conditioning demands and solar radiation patterns. Moreover, the sensible heat fluxes of the urban areas were always higher than those of the other land-cover types. Consequently, we concluded that our new method allowed us to estimate anthropologic heat discharge in urban areas, and is quite useful to investigate the heat island effect in urban areas.