Estimating the Soil Heat Flux from Observations of Soil Temperature Near the Surface

Abstract

AbstractA method was described for estimating soil heat flux by measuring soil moisture content and soil temperature at two or three depths near the soil surface. The method utilizes an analytical expression of heat flux for a semi‐infinite homogeneous soil profile for which the surface temperature is described by a Fourier series. For relatively homogeneous soil, the estimates of soil heat flux, based on observation of temperature at two depths, compared well with values of heat flux determined with the temperature integral method. Estimates were best when one of the measurement depths was very near the surface (≤ 1 cm) and the other between the 10‐ and 20‐cm depths. When soil profiles were nonhomogeneous it was found that three rather than two depths of temperature observation should be considered. Although the analytical solution for estimating the heat flux strictly does not apply to nonhomogeneous soils, heat flux values obtained with the proposed method compared favorably with those computed with the temperature integral method.