Dual thermal probes near plane interfaces

The dual probe estimates the thermal properties of soils. Because it is str ongly dependent on water content, volumetric heat capacity is useful for mo isture estimation. A previous study of probe errors due to soil heterogenei ty is taken further with the aid of a new solution for instantaneous line s ources near a plane interface between two regions. The solution allows for different conductivities and heat capacities in the regions, but requires u niform diffusivities. This condition holds reasonably well near wetting fro nts in a range of soils. Previous error bounds are confirmed and sharpened. The conclusion in the previous study that errors are small when the hetero geneity is no closer to the probes than the probe separation (typically 0.0 06 m) is reinforced. The expectation that the dual probe gives good resolut ion of water content close to fronts and interfaces is strengthened.