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Sea level in the Mediterranean: a first step towards separating crustal movements and absolute sea-level variations

TitleSea level in the Mediterranean: a first step towards separating crustal movements and absolute sea-level variations
Publication TypeJournal Article
Year of Publication1996
AuthorsZerbini S, Plag HP, Baker T, Becker M, Billiris H, Bürki B, Kahle HG, Marson I, Pezzoli L, Richter B, Romagnoli C, Sztobryn M, Tomasi P, Tsimplis M, Veis G, Verrone G
JournalGlobal and Planetary Change
KeywordsBlack sea, changement climatique, climate, climate change, environment, geophysic, géophysique, hausse du niveau de la mer, impact, interaction, Mediterranean sea, Mer Méditerranée, Mer Noire, monitoring, network, ocean, sea level rise, trend

The SELF (SEa Level Fluctuations: geophysical interpretation and environmental impact) project has been developed and realized in the framework of the Environment Programme designed by the Commission of the European Communities. The SELF project was aimed at providing a reliable base for the determination, in the Mediterranean area, of sea-level variations which could then be used as a possible indicator of climate changes and to study the interactions taking place among the ocean, the atmosphere., and the solid Earth. The project has made it possible to define a consistent network of well-established tide gauges encompassing the Mediterranean Basin as far as the Black Sea and to determine to centimeter accuracy the tide gauge benchmark heights in a global well-defined reference system such as the one provided by the SLR/VLBI space techniques. The SELF network constitutes, for the Mediterranean, the necessary prerequisite towards achieving the actual capability to separate vertical crustal movements from true sea-level variations. This has been accomplished through the use of space techniques namely SLR, VLBI and GPS in conjunction with Water Vapor Radiometer observations and absolute gravity measurements. The analysis of the available tide gauge records has shown a high spatial coherence of the annual to multidecadal sea-level variability. Sea-level fluctuations at periods longer than two months were found to be strongly correlated with air pressure. The seasonal cycle was found to be variable in time. Relative sea-level trends determined from records longer than 30 years are less than 1.5 mm/yr. Crustal movement rates as determined from the tide gauge records are in general of the order + 1.0 mm/yr. The geological observations have shed light on the fact that a marked variability of crustal movements occurs on both the temporal and spatial scale, and it represents a major contribution to relative sea-level fluctuations. This fact has been verified for the selected sector which belongs to one of the more geodynamically active areas of the Central Mediterranean (Aeolian Archipelago). However, this work has shown that, at least at the tide gauges included in the present study, crustal movements are small compared to the decadal to multidecadal sea-level variability but of the same order as the long-term trend in sea level, thus necessitating a careful monitoring if crustal movement is to be separated from the oceanographic contribution to relative sea-level changes.

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