Measurements of snow water equivalent using multiple-offset ground-penetrating radar

Ground-penetrating radar (GPR) measurements of snow water equivalent depend onaccurate information of the radar wave propagation velocity in the snow cover, aswell as on the relationship between the dielectric constant and snow density. This paperevaluates a simplified procedure to derive snow water equivalent from GPR traveltime data only, using multiple-offset GPR antennas arranged in an array. The dielectricconstant and the depth of the snow cover are determined by multi-channel measurementsusing several combinations of transmitter and receiver antennas in the array,based on basic common-mid-point principles. This set-up enables continuous determinationof both snow cover depth and snow density along the measurement profile,which reduces the uncertainties due to spatial variation of snow density. The measurementsystem is evaluated using manual snow depth and snow density measurements attwo sites in northern Sweden during winter 2004/2005. Results show that the spatialvariation of both snow depth and snow density were improved with the multi-offsetmeasurements compared to the use of a single channel measurement.