Determination of Snow Water Equivalent for Dry Snowpacks Using the Multipath Propagation of Ground-Based Radars

Abstract

Determining snow water equivalent (SWE) in a fast and non-destructive way is a key request for many hydrologists and snow scientists. To this aim, microwave ground-based radars represent a viable solution, but often the simultaneous measurement of both the snowpack depth and density (the key ingredients for the SWE) is very complex, inaccurate, or requires difficult procedures and equipment.This paper presents a novel radar technique for self-standing calculation of the SWE that can be applied to bi-static radars. This technique, based on the multipath propagation of the radar signal into the snowpack, only require a radar with two fixed antennas, without any other device, movement of the antennas, or a-priori empirical assumptions. This makes such a technique particularly suitable for light and portable radars for rapidly probing large areas, providing for example an innovative validation means for satellite-based microwave remote sensing methods. The proposed technique was demonstrated using a stepped frequency modulated continuous wave (FMCW) radar in field conditions for dry snow, delivering results for snow depth and SWE, benchmarked by manual analyses of the snowpack, with a mean absolute error better than 5 cm.

Snow Layer Detection by Pattern Matching in a Multipath Radar Interference Scenario

“…Unavoidably, reflections and multiple paths are present in the system, which generate disturbances and deteriorate the estimation process. Although in some cases multipath propagation can be useful to collect additional information as pointed out by Espín-López and Pasian (2020), in general, it constitutes a source of disturbances. The presence of multipath interference is common among various technologies, including wireless communications, radar tracking, and positioning.…”

A Microwave Frequency Range Experiment for the Measurement of Snow Density and Liquid Water Content

“…These radars propose a remote monitoring system for the depth of snow [10] or even the snowpack stratigraphy [11]. Finally, the possibility to use an electromagnetic test bench using a vector network analyzer (VNA) to extract very precisely the effective density from the real part of the dielectric permittivity has been demonstrated for a dry snowpack in [12], [13]. However, all these methods only measure a delay time or a phase shift, thus only allowing the determination of the real part of the snow permittivity 𝜀 .…”