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

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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.