Analysis of heat and moisture trasfer in urbanized area

在第一部分中，分析了日本气象厅和东京都政府25年来每小时的气象资料，以探测温度和湿度的趋势。我们发现，最近的日最低气温一直在上升，而绝对湿度已停止下降，甚至有所上升。研究了年水热平衡，以确定城市化和年降水量对水热平衡的影响。在第二部分中，我们建立了一个考虑复杂地形、土地利用、城市冠层和人为热量和水分释放的三维区域模型。该模型由四个子模型组成。即地下的热传导模型、地表的热湿平衡模型、基于动量、热量和质量通量恒定假设的表面层模型和求解一组方程的Ekman层模型。在这里的Ekman层模型中，我们采用了经过稳定平稳化修正的k-e湍流模型。通过对夏季晴日的数值模拟发现，温度和湿度受土地利用、海风的影响，夜间人为放热对温度的影响较大，汽车和人体的放湿作用较小。第三部分是对地下和地表的水传热进行分析。开发了一个基于物理的分布模型，以了解所涉及的水文过程。该模型在多摩河中游进行了性能测试，并于1992 - 1994年应用于东京都，网格尺寸为1km，时间步长为1小时。土地利用的变化导致了蒸散量和博文比的显著变化。

In the first part, the meteorological data obtained hourly over twenty five years by the Meteorological Agency of Japan and the Tokyo Metropolitan Government were analyzed to detect the trends in temperature and moisture. We found that the daily minimum temperature has been increasing while absolute humidity has stopped decreasing or rather increased recently. Annual balances of water and heat were also studied to confirm the effects of urbanization and annual precipitation on water and heat balances.In the second part, we developed a three-dimensional regional model that takes into account of complex topography, land use, urban canopies and anthropogenic heat and moisture release. The model is made up of four submodels. That is, a heat conduction model in ground, a heat and moisture balance model at ground surface, a surface layr model that is based on the assumption of constant momentum, heat and mass fluxes and an Ekman layr model that solves a set of equations. Here in the Ekman layr model, we adopted a k-e turbulence model modified for stable statification. Through numerical simulation for summer fine days, it is found that the temperature and humidity are affected by land use, sea breeze and that anthropogenic heat release exerts considerable influence on temperature at night while moisture release from cars and human bodies are of minor role.The third part is devoted the analysis of water and heat transfer in ground and at ground surface. A physically-based distribution model was developed to understand the hydrological processes involved. The model performance was tested in the middle reach of Tama river and then applied to Tokyo Metropolis from 1992 to 1994 with the mesh size of 1km and time step of a hour. It is made clear that the changes in land use have led to considerable change in evapotranspiration and the Bowen ratio.