STP01 soil temperature profile sensor offers an accurate temperature difference measurement at five measurement locations at 0.02, 0.05, 0.1, 0.2, and 0.5 m below the soil surface. It also has a well-specified and fixed distance between the measurement locations. STP01 contains 5 matched thermocouples, at locations A to E in Figure 5, and one reference temperature sensor (Pt100 type) at location E at 0.5 m depth. By having the reference temperature measurement in the sensor and only measuring differential thermocouple voltages (relative to the reference at 0.5 m), the uncertainty of the temperature difference measurement is very low: ± 0.02 °C is attainable. Simple copper-conductor signal wire is used in STP01’s cable. As an extra, a heating wire is incorporated in STP01. Analysis of the temperature change during the heating interval serves as a self-test.
STP01 accurately measures the temperature profile of the soil at 5 depths close to its surface.
