Coastal Tide Gauge Observations: Dynamic Processes Present in the Fremantle Record

Coastal sea level variability occurs over timescales ranging from hours to centuries. Globally, the astronomical forces of the Sun and the Moon are the dominant forcing which results in the tidal variability with periods of 12 and 24 h. In many regions, the effects of the tides dominate the water level variability - however, in regions where the tidal effects are small other processes also become important in determining the local water level. In this paper, sea level data from Fremantle (tidal range similar to 0.5 m), which has one of the longest time series records in the southern hemisphere, and other sea level recoding stations from Western Australia are presented to highlight the different processes ranging from seiches, tsunamis, tides, storm surges, continental shelf waves, annual and inter-annual variability. As the contribution from each of these processes is of the same order of magnitude - the study of sea level variability in the region is very interesting and reveals both local and remote forcing.