Tidal Gauge Stations at Deception and Livingston Islands 2007-2014 : records, analysis and georeference.

Abstract

In order to establish an approximate value of the mean sea level in the South Shetland, in 2007 the first gauges in Livingston and Deception islands was installed. Due to the harsh conditions of the area, with sea ice for long periods of the year, pressure sensors were installed near the coast but deep enough to not be affected by ice.
Two tidal records of more than six years duration were obtained at Livingston and Deception islands since December 2007 to February 2014. DECMAR tide gauge station is located at Deception Island and LIVMAR tidal station at Livingston Island. Data were obtained using two moorings with a SAIV TD304 bottom pressure sensor at points near the coast. Additional data of temperature and salinity of seawater were obtained simultaneously with the tidal records. Harmonic analysis has been used to obtain the amplitudes and phase lags of the most energetic tidal constituents. The instruments were anchored near the coast, to minimize errors in the subsequent referencing to the benchmark. For tidal observations, a land benchmark was used as the primary reference point. These tidal gauge benchmarks (TGBM) were well-marked points located on an exposed rock, and linked to GPS benchmarks (GPSBM) near the gauges. The analysis of the time series has enabled to study the contribution due to tidal. Sea level have been correlated with meteorological and oceanographic variables.
By referencing the bottom pressure sensors to the benchmarks, it was possible to calculate MSL relative to a precise levelling network for the period analysed. The sensor reference levels were linked to the TGBM by linear fitting of the instantaneous measurements of the sea level observed by tide staff to the data obtained from the pressure sensors. In order to correlate the two measures, data from the meteorological station were used.
A more accurate mean sea level was obtained in the geodetic reference benchmarks. The orthometric heights may be calculated, from the ellipsoid height, obtained from the GPS measures, absolute gravity measures and geometric levelling differences.