Without protection, temperature sensors absorb solar radiation, yielding readings higher than the true air temperature. To reduce this error, temperature sensors on the USU Environmental Observatory are shaded with both a Gill shield and an aspirated shield. A Gill shield is 'naturally ventilated,' consisting of multiple stacked white plates that block direct and reflected solar radiation, yet permit easy passage of air. In high-sun and low-wind conditions, not enough wind flows past the sensor to cool it. In the aspirated shield, a solar-powered fan draws air past the shaded sensor to produce a more accurate measurement. Both old and new measurement techniques are being compared, with two types of thermistors in each of the two shield types. The upper two graphs show data for yellow bead thermistors. The lower two graphs show data for finewire thermistors.
