Micro-meteorological study on the effect of straw-matting

Abstract

In this paper, we studied the effect of straw-matting in the winter season.On the comparing with the case of being covered with straw-matting all the day long and the case of being uncovered in day time, as shown Fig. 1, it was made clear that in the latter the minimum ground surface temperature is higher shout 2°C on the mean and 5.8°C on the maximum than the former.Then, it is very convinient, if we know that in the case of covering straw-matting, how much thick of straw-matting is desirable for the certain cold.When the surface temperature of straw-matting is y and its amplitude A, if it is assumed that there is such a relationship as y=A sin nt, the diurnal change of the temperature at Xcm depth, is shown as following formula.Y=Ae-X/K√n/2sin(nt-X/K√n/2)When the diurnal range of the temperature at Xcm depth is placed to R, it isR=2Ae-X/K√n/2The formula is transformed as following.X/K√n/2loge=log2A-logROn the straw-matting of 11cm thick and of 18cm thick, being calculated (log2A-logR) respectively and counted K from those values, K is about 0.045.Therefore, the following formula is obtained.X=17(log2A-logR)There are close relations between the diurnal range of the surface temperature of the straw-matting (2A) with the diurnal range of the surface temperature at the uncovered ground, and the diurnal rang of the ground surface temperature under the straw-matting with the minimum ground surface temperature under the straw-matting.From the above relations, in order to know that, when the diurnal range of the uncovered ground surface temperature is obtained, how much thick of straw-matting are desirable that the temperature under the straw matting might not lower less than the certain temperture, the figure such as Fig. 2 was tried to make.