Impact of Environmental Pressure Changes on High Precision Measurements

Abstract

Stable environmental temperature is essential for high precision measurements. Underground caves, or underground laboratories, far from the entrance are generally assumed to provide such ideal, extremely stable environment. However, atmospheric pressure variations have an indirect effect on the temperature of such sites. Two relevant effects are adiabatic temperature change and pressure-dependent self-heating of electronic instruments. In this study a 64-days long temperature timeseries recorded by a tilt-meter was analysed to identify and characterize these effects. We found that large, slow temperature changes can be removed properly, allowing both of the aforementioned effects to be detected in the residual. Furthermore, some key parameters of the pressure–temperature transfer function can be estimated. However, a precise model of pressure dependence could not be obtained, possibly due to the nonlinear behaviour of the process and/or insufficient excitation levels. The results demonstrate that these two effects impose opposite requirements on the instrument’s thermal insulation of the instrument. Consequently, either these effects should be taken into consideration, or the generated heat should be conducted away through a properly sized metallic path eliminating the pressure dependence of self-heating.