Snow plates: preliminary results

This paper presents the design, construction and calibration of field instrument to measure snow water equivalence (SWE). This instrument, referred to as a ‘snow plate’, consists of a 1 sq m circular, perforated aluminum plate assembly mounted on three loadcells. When coupled with a ultrasonic snow depth sensor, measurements of snow density can be made. This plate was designed to make high frequency high resolution SWE measurements on the Front Range of Colorado. Snow events typically are temporally isolated and produce a SWE of 2 cm or less. The tested plate can measure a maximum SWE of 34.5 cm. The maximum SWE capacity can be increased by using higher capacity loadcells. A preliminary 0-4.5 SWE (0-45 kg) loading/unloading calibration test shows that the plate has an average error of 0.0284 cm SWE (0.284 kg), with a maximum error of 0.0817 cm SWE (0.817 kg) at 3 cm SWE (30 kg). Ninety-five percent of the 1210 test measurements had errors of less than 0.05 cm SWE (0.5 kg). This test indicates that the snow plate may be a useful alternative to the traditional snow pillow for measuring SWE. This instrumentation is portable, requires minimal maintenance, and may be used in dense forests and rocky and sloped terrain. The snow plate may help provide important information on the effects of topography and vegetation on snow accumulation.