Towards automated ‘Ground truth’ snow measurements—a review of operational and new measurement methods for Sweden, Norway, and Finland

Abstract

AbstractManual snow measurements are becoming increasingly expensive and climate‐change‐imposed snow alterations are affecting run‐off and frost patterns; snow observations are included in run‐off modelling, making reliable snow observations of utmost importance. Multiple new and modified ground‐based techniques for monitoring snow depth, density, snow water equivalent (SWE), wetness, and layering have been tested over the last decade, justifying a review of such methods. Techniques based on snow mass, electrical properties, attenuation of radioactivity, and other miscellaneous properties are reviewed. The following sensors seem suitable for registration of temporal variations: ultrasonic (depth) and terrestrial laser scanning (depth), several snow pillows at the same location (SWE), Cold Regions Research and Engineering Laboratory/Natural Resources Conservation Service weighing sensor (SWE), Snowpower (depth, density, SWE, and wetness), active and passive (cosmic) γ‐ray attenuation (SWE), and adjusted time domain reflectometry probes (density and wetness). Ground‐penetrating radar (GPR) is, depending on the design and operation modes, suitable for different purposes; when arrays of antennas are pulled by a snowmobile, the technique is suitable for monitoring of spatial variations in depth, density, and SWE for dry snow. Techniques are under development, which will hopefully improve the accuracy for wet snow measurements. Frequency‐modulated continuous wave GPRs seem fit for measurement of snow layering. Some suggested techniques are not operational yet. Copyright © 2010 John Wiley & Sons, Ltd.