Soil Surface Temperature Difference Between Steel and Hypalon Pillows

Systematic bias in data collection systems is often difficult to identify and moreover, on a site specific basis, hard to correct. Systematic bias in the SNOTEL record between steel and hypalon pillows has been identified and ranges between 0% and 25% (Julander and Bricco, 2006, Osterhuber, 1996). Observationally, the greater differences are typically at lower elevations and warmer temperatures while higher elevation, cooler sites typically have lower differences or none at all. Since originally the entire SNOTEL system was installed with steel pillow and since that time many steel pillows have been replaced with hypalon, it is essential to take a second look at these parameters to insure data consistency and accurate results. Hypalon pillows could become a heat sink, absorbing energy in the summer and slowly releasing it through later periods which could impact early season snow accumulation. The black pillows might possibly increase solar energy absorption during ablation, increasing melt rates in the spring. To test this hypothesis, temperature sensors were placed under co-located hypalon and steel pillows at Parleys Summit and Trial Lake SNOTEL sites in Utah. Results indicate that there is a substantial temperature difference and that it is possible that this difference could impact snow accumulation and ablation.