CoAuthors

Christopher Watson (University of Tasmania, Australia)

Traditional leveling serves as the primary technique used to assess the stability of tide gauges relative to the crust as well as to provide their ellipsoidal height by means of the vertical connection between the tide gauge zero and a nearby GNSS site.

The GNSS reflectometry (GNSS-R) technique provides valuable information related to the geometry and physical properties of the reflecting surfaces surrounding a GNSS antenna, including the vertical distance to them. Here, we use sea-surface reflections of GNSS signals, recorded as oscillations in the observed signal-to-noise ratio (SNR), to estimate the GNSS to tide gauge (TG) leveling connection. This can be done remotely, continuously and at no additional cost, yielding a possible alternative to traditional leveling surveys.

We present results of a leveling campaign conducted in Spring Bay, Australia, where comparison with traditional in situ leveling reveals promising differences at the millimeter level. These differences include errors from this technique, mainly due to the tropospheric refraction, but also errors related to the traditional in situ leveling (e.g., errors in the GNSS antenna calibration) and to the calibration of the TG zero. The latter opens the possibility of using this technique to monitor the stability of the TG zero.