A simple experimental apparatus for testing soil heat flux plates= Un semplice apparato sperimentale per la valutazione del corretto funzionamento dei sensori per la misura del flusso di calore nel suolo

摘要: Soil heat flux plays an important role into the SVAT (Soil-Vegetation-ATmosphere) energy exchanges. Soil heat flux is usually measured by small plates located close to the soil surface. The evaluation of the correct functioning of the soil heat flux plates is generally performed by the manufacturers that in some cases refuse to test probes that have already been used in the field or which have been modified for specific experimental needs. In this paper we describe a simple apparatus that can be built in any laboratory and allows in the first place to check whether the heat flux sensors are working properly, considering the pattern of the heat flux measured in response to different thermal gradients imposed on the two sides of the plate. Secondly, the experimental apparatus allows to verify whether the sensitivity constants provided to the manufacturers (different for each sensor) are corrected, comparing the measured heat flux pattern with that obtained by applying the Fourier law, knowing the temperatures applied to the two plate faces and the thermal conductivity of the plate. The use of simple materials readily available in any laboratory make this apparatus easily reproducible, and the results show that experimental setup allows the achievement of the experimental objectives.