Snow depth variations estimated from three-frequency GPS interferometric reflectometry

Nowadays, GPS multipath can be used to estimate snow depth, soil moisture and vegetation growth using signal-noise to radio (SNR) data. Particularly with the modernization of GPS, one new signal, called L5, has been broadcasted by Block IIF satellites, the combination of three-frequency (L1, L2 and L5) observations may help remove the ionospheric delay errors and obtain better multipath signals. In this paper, the pseudorange and phase multipath are extracted from three-frequency GPS pseudorange and phase combinations at GANP station in Slovakia with available co-located snow data, which are used to estimate snow depth variations based on the GPS Multipath Refletometry (GPS-MR) theory. Snow depth estimations from three-frequency GPS pseudorange combinations are compared with in-situ observations, which shows a correlation of 0.83 and RMSE of 0.11m, while results from three-frequency GPS phase combinations have a little better correlation of 0.86 and RMSE of 0.08m. However, the results from dual-frequency (L1 and L2) combinations have a much lower correlation of 0.64 and larger RMSE of 0.16m. Therefore, it is better to estimate snow depth using three-frequency combinations than double-frequency measurements.