Evergreen trees as inexpensive radiation shields for temperature sensors

Evergreen trees provide temperature sensors with shielding from solar radiation and an elevated location above the snowpack. Sensors were deployed with simple funnel radiation shields in the Sierra Nevada, California, and Rocky Mountains, Colorado. Compared with unaspirated, Gill- shielded thermistors, inexpensive self- recording temperature sensors hung in dense stands of trees have less than 0.8 degrees C (0.4 degrees C) mean difference in daily maximum (mean) temperature. In contrast, sensors in sparse and isolated trees had a bias of 2-5 degrees C (0.3-1.3 degrees C) in daily maximum (mean) temperature. Sensors on poles were biased 5-13 degrees C (0.5-3.0 degrees C) for daily maximum (mean) temperatures. In locations with deep winter snowpacks, sensors can be raised high into a tree using a pulley system.