The influence of thermal, hydrologic, and snow deformation mechanisms on snow water equivalent pressure sensor accuracy

TitleThe influence of thermal, hydrologic, and snow deformation mechanisms on snow water equivalent pressure sensor accuracy
Publication TypeConference Proceedings
Year of Conference2002
AuthorsJohnson, J. B., and Schaefer G. L.
Conference Name70th Annual Western Snow Conference
Series TitleProceedings of the 70th Annual Western Snow Conference
Date PublishedMay 2002
PublisherWestern Snow Conference
Conference LocationGranby, Colorado
KeywordsSWE, Pressure transducer error, Heat budget, Snow core
Abstract

A five-year field study was conducted to determine the mechanisms that cause snow water equivalent (SWE) pressure sensor measurement errors. We monitored a 3-m snow pillow and installed three prototype electronic SWE sensors to examine how SWE errors occur. We measured heat flux in the sensors and the soil, snow temperature, soil moisture content, and soil thermal conductivity. The SWE of snow cores were used to assess the accuracy of the sensors. Results indicate that SWE measurement errors occur when the snow/SWE sensor and/or the snow/soil interfaces are at the melting temperature of snow. SWE over measurement errors occur when the sensor heat flux is less than the surrounding soil. SWE under measurement errors occur when the heat flux through the sensor is greater than through the soil. The most severe errors occur during the transition from winter to spring when the snow cover first reaches an isothermal condition producing a maximum difference in snowmelt rate between the snow/SWE sensor and snow/soil interfaces. SWE measurement errors are minimized when the sensor is designed to match the thermal properties of the surrounding soil, allow water to flow through the sensor, or to diffuse heat into the adjacent soil.

URLsites/westernsnowconference.org/PDFs/2002Johnson.pdf