Ocean signals in tide gauge records

Tide gauges are designed to measure changes in water level relative to land. However, vertical motions of the earth's crust manifest themselves as apparent water level changes in tide gauge records. These crustally induced changes are often small in amplitude relative to the wide range of oceanic processes which affect water level in coastal regions. Vertical crustal motion can best be studied by first removing oceanic variability from the time series. In this paper we summarize the major oceanic signals in tide gauge records. We take the approach that the oceanic signals are unwanted “noise” in the data. Methods are described for removing or at least reducing the various oceanic signals. These oceanic signals span a broad range of time scales from tides to interannual variability associated with the El Niño phenomenon and secular sea level change from a number of oceanographic effects.