Amplitude estimation of dominant tidal constituents using GNSS interferometric reflectometry technique

Using a coastal Global Navigation Satellite System (GNSS) station, one can measure sea surface height (SSH) using GNSS Interferometric Reflectometry (GNSS-IR) technique as it gives vertical distance between the antenna and the reflective surface in a height reference frame. In this study, Signal-to-Noise Ratio (SNR) data of a GPS station located in Honolulu, Hawaii, were observed over a one-month period to estimate the amplitude of the dominant tidal constituents. SSH values acquired from GNSS-IR are then compared to traditional tidal observations obtained from a nearby tide-gauge station. Obtaining a Root Mean Square Error (RMSE) of 11.5 cm and a correlation of 0.87 between SSH values obtained from GNSS-IR and tide-gauge, we estimated the amplitudes of dominant tidal constituents (M2, S2, K1, P1, 01) with maximum and minimum amplitude differences of 2.38 and 0.28 cm, respectively. Next, a set of control points around the GNSS station were chosen and the FES2012 global tide model was used to calculate the amplitudes of those constituents one more time. The maximum and minimum differences in amplitude obtained from the tide-gauge station and the FES2012 model were 3.65 and 0.31 cm, respectively. This study suggests that the GNSS-IR technique can be used as a tool for estimating tidal constituents over a short period of time in the order of one month.