Full Winter Season Measurement of Snowpack Height and Backscattering Coefficient Using a 120-GHz Ultrawideband FMCW Radar

In this article, we present a 120-GHz ultrawideband (3.3 GHz) frequency-modulated continuous wave (FMCW) radar, designed using a millimeter-wave (mmWave) transceiver, and its application to the measurement of snowpack height over two full winter seasons. This system achieves 2 cm accuracy across the diverse snowpack and environmental conditions encountered during the winter season. Its main advantages over conventional measurement techniques are good performance during heavy snowfall, correct detection of fresh fallen snow, spatial averaging, and low temperature dependence. Furthermore, our system is able to measure the backscattering coefficient of the snowpack, which is predominantly influenced by the liquid water content (LWC) of its surface layer. This relationship is confirmed by experimental measurements and numerical simulations, and could enable noninvasive first layer LWC estimations. Hence, we prove mmWave radar to be a reliable technology for snowpack monitoring under different environmental and snowpack conditions, with a wide range of applications in hydrological forecasting, avalanche risk assessment, and environmental monitoring.