Horizontal and vertical transport of heat and moisture over complex terrain.

地表与大气之间的热、湿、动量交换过程还不够清楚。大气与地表相互作用的研究不仅对阐明局部气象学，而且对研究全球气候变化具有重要意义。本研究的目的是通过野外观测和数值试验来了解简单河谷和盆地的热湿输送机制。伊纳山谷是日本最深的山谷之一。分析了该山谷在晴朗和无风天气的温度和湿度剖面，发现深谷的混合层由湍流混合层和准混合层两层组成。前者是较低层，主要由地表热通量产生的湍流和平面上的正常混合层保存。后者为上层，有轻微的稳定分层，但白天该层温度不断升高。准混合层不是湍流形成的，而是由陡坡上空的回流风环流形成的。对准混合层进行了数值模拟，发现山地高度必须高于平坦地形上形成的混合层，才能形成qudsi混合层。得到了复杂地形上复风和复风的线性解。线性模型可以明确风强度与地形水平比例尺之间的关系。结果表明，当地形水平尺度在100km左右时，降风最强。当地形的水平尺度比这小得多时，位温的水平分布趋于均匀。

Heat, moisture and momentum exchange process between the ground surface and atmosphere has not been clear enough. Study of the interaction between the atmosphere and the land surface is very important not only to clarify the local meteorology but also to study global climate change.The purpose of this study is to understand the mechanism of heat and moisture transport over simple valley and basin by field observation and numerical experiments.Ina valley is one of the most deep valley in Japan. Temperature and moisture profiles observed by radio sonde in this valley on clear and calm days are analized and it was found that the mixed layr in deep valley is consisted with two layrs, a turbulent mixed layr and a quasi mixed layr. The former is lower layr and is preserved by turbulence mainly generated by surface heat flux as well as the normal mixed layr over flat surface. The latter is upper layr and has slight stable stratification though temperature of this layr keeps increasing in daytime. The quasi mixed layr is formed by the circulation of anabatic wind over mountain slopes instead of turbulence.The quasi mixed layr was simulated by a numerical model and it was found that the mountain height must be taller than the mixed layr formed over flat topography for the formation of the qudsi mixed layr.A linear solution for anabatic and katabatic wind over complex topography is obtained. The linear model can clarify the relation between intensity of the wind and horizontal scale of topography. The results show that the katabatic wind will be strongest when the horizontal scale of the topography is about 100km.If the horizontal scale of the topography is much smaller than this, potential temperature tends to distribute to be horizontally uniform.