Ultra-broadband portable microwave FMCW radars for measuring snow depth, snow water equivalent, and stratigraphy: practical considerations

The properties of seasonal snow and near surface polar firn can be measured using radars operating at the microwave frequencies. These frequencies offer an optimal combination of bandwidth and penetration required for snow studies. Because the velocity of microwave signals in dry snow and firn is primarily controlled by density, wave travel times can be converted to snow depth, snow water equivalent (SWE), and layer thickness, which are the main snow properties of interest in hydrologic and climatologic studies. The accuracy with which depth, SWE, and layer thickness can be determined varies with environment and snow properties. Sharp dielectric contrasts between snow layers and the underlying ground produce excellent results, while gradational boundaries and low contrasts can be problematic. Liquid water can also make penetration and interpretation difficult. Nevertheless, mobile microwave radars represent one of the most promising methods for mapping snow properties at landscape scales. Here we discuss some practical considerations that must be accounted for when using radars to measure snow properties.