Monitoring snow water equivalent using low-cost GPS antennas buried underneath a snowpack

The GPS refractometry method is presented to derive snow water equivalent (SWE) by using refracted GPS L1 signals from a low-cost antenna buried underneath the snowpack. The GPS monitoring system is installed at 2536 m a.s.l. in the Swiss Alps. GPS refractometry is able to correct the influence of the snowpack above the buried antenna. The systematic and stochastic snow induced effects in the GPS residuals are significantly reduced by estimating the SWE above the antenna. The refined method is able to estimate the SWE hourly over a full season and results are highly correlated to the reference sensors data with a median relative bias of less than 10 %.