A practical test of a telemetered accoustic snow depth sensor

During the 1987-88 winter, data from an accoustic snow depth sensor and observed snow depth were compared at the Central Sierra Snow Laboratory in the Sierra Nevada of California. The Sierra snowpack is characterized as being deep and wet with melt occurring during mid-winter. Snow depth during the test period reached 190 cm and surface snow densities ranged from 110 kg/cubic meter to 400 kg/cubic meter. Surface melt-freeze crusts reached a thickness of 40 cm. Correlation between sensor telemetry data and observed 8 am snow depth was 0.99 with a standard error of estimate of 3.6 cm. On an hourly basis, snow depth from the accoustic sensor varied inversely (with) changes in air temperature during periods of no precipitation. Snow depth variations of up to 12 cm occurred between hourly readings and went as high as 17 cm over a 24 hour period. During the test period, air temperature ranged from -18 to 17 degrees centigrade with differences as high as 19 degrees centigrade between the maximum and minimum. The variations associated with temperature change were not (etc).