Atmospheric-Soil System Model and Simulation.

Abstract

The atmospheric environment of a certain region is generated with many external and internal factors intertwined in complexity. Solar radiation, precipitation and atmospheric movement on a large scale are examples of external ones, and topography, vegetation, soil and water are examples of internal ones. The factors which we can control are the internal ones, but the wind, the factor which seems to be external at a glance can be changed to some degree with the use of a fan or the reforms of topography and vegetation.In this paper, we discuss how much we can control the atmospheric environment near the ground, especially the thermal environment related to plant growth. For simplification here, we treat one-dimensional situation, i.e., heat balance structure with a flat surface. Moreover, we treat it at night in winter for two reasons. One is in such a situation of stable condition, then the effects of soil for the atmosphere may be clear. And the other is in such a situation we can discuss in relation to practical problem like a frost damage.A group of equations that represents atmospheric-soil heat balance was constructed. The model based on this equation system was made. After the model had been ascertained with observed data, we simulated under some different conditions, then we could get realistic results. With these results the effects of wind speed and soil moisture to the thermal environment and to the heat balance structure were examined.The effect of soil moisture (thermal property of soil) on air temperature reaches to a fairly high level as the wind becomes weak to a certain degree (Fig. 5).The influence of wind speed on soil temperature exists for a dry soil slightly, but almost vanishes as the soil becomes wet (Fig. 6).The effect of soil moisture on heat balance near the ground is clearer as the wind becomes strong (Fig. 7).The influence of wind speed on heat balance near the ground exists on dry soil slightly.