Design and evaluation of an inexpensive radiation shield for monitoring surface air temperatures

Abstract

Inexpensive temperature sensors are widely used in agricultural and forestry research. This paper describes a low-cost (∼3USD) radiation shield (radshield) designed for monitoring surface air temperatures in harsh outdoor environments. We compared the performance of the radshield paired with low-cost temperature sensors at three sites in western Montana to several types of commercially available instruments. Comparisons included observations made under a tree canopy and in full sun with both passive and mechanically aspirated radiation shields. Beneath a forest canopy, temperature sensors housed within the radshield showed bias of less than 0.5°C for hourly temperatures when compared with the same sensors housed in an unaspirated Gill-style shield. Sensors and shields mounted on poles in full sun were slightly warmer under low-wind conditions, but overall were cooler than data from an adjacent Remote Automated Weather Station (RAWS). When compared with observations from a high-quality temperature sensor housed in a mechanically aspirated solar radiation shield used in the Automated Surface Observing Systems (ASOS), observations from inexpensive temperature sensors housed within radshields were biased with mean absolute error of 0.99°C, but performed as well as those housed within a more expensive, commercially available Gill-style radiation shield. Our initial evaluation suggests that the radshield, instrumented with a low-cost sensor is suitable for monitoring surface air temperatures across a range of outdoor environments.