Methods for estimating thermal diffusivity of the subsoil based on annual temperature variations
1988
Thunholm, B. (Sveriges Lantbruksuniv., Uppsala (Sweden). Inst. foer Markvetenskap)
Four methods for estimating thermal diffusivity were compared using subsoil temperatures from six Swedish sites. Two methods were based on the damping of amplitude and on the phase shift that occurs in the annual temperature wave with increasing depth. The other methods were based on Fourier series and on a numerical solution. Generally, the amplitude, the phase and the Fourier series yielded similar results; still the Fourier series method seemed to be most appropriate where the annual temperature wave was influenced by freezing and snow cover. The numerical method was not suitable, mostly because of difficulties involved in handling variations in thermal conductivity with depth.
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