COMPUTING MEAN APPARENT SOIL THERMAL DIFFUSIVITY FROM DAILY OBSERVATIONS OF SOIL TEMPERATURE AT TWO DEPTHS

Abstract

We compared the outcomes of four different methods for indirectly computing the mean apparent soil thermal diffusivity from measured daily maximum and minimum temperatures at two depths in the soil profile. These methods were all based on the analysis of heat transfer in the profile by conduction. Sets of data taken in the same soil type at the 10− and 20-cm depths under bare and grass-covered conditions were utilized in the study. The results from the four methods were not in agreement. The incongruities tended to be greater when using the data for the grass-covered soil. Unless they are compared with results of direct simultaneous measurements of the thermal diffusivity, it is difficult to judge which is the best method for indirect computation of thermal diffusivity from measured soil profile temperatures.