GNSS – Interferometric Reflectometry, sea level measurements and spectral artifacts

Abstract

Commonly sea level variations are monitored by tide gages that measure the relative sea level (RSL) with respect to a local reference on land. RSL measurements are a combination of the global sea level variation and the local vertical land motion. Larson et al.,2012 developed the interferometric reflectometry technique (GNSS-IR) and demonstrate that sea surface height can be monitored at the level of a few centimeters using a single GNSS antenna facing the seashore. In that case, the local reference point matches with the antenna mount that can be monitored directly in a global reference frame. Thus the GNSS-IR technique allow to monitor the global Sea-level directly from a single measurement. We discuss the results obtained for a few Sea-level time series obtained from existing GNSS permanent stations in the Mediterranean area. We analyse the spectral content of tidal components and examine the origin of spurious signals observed in the periodograms, due to satellite-driven aliasing effects.