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Abstract: Sea level observations from tide-gauge records located at the Adriatic coasts are analysed. The estimated sea level trends show variability in time and space. Spatial variability is assessed by estimating the differential trends by reference to Trieste. For many of the stations the differential trends become smaller than the corresponding error bars. This indicates that the land, atmospheric and oceanic contributors to sea level change are, at long scales, uniform in the basin. Observed trends in the longer records differ significantly for the periods before 1960 and after 1960. Atmospheric forcing has been a significant contribution in sea level variability for the period 1960 onwards. The atmospheric trends account for −0.8mm/year for the period 1960–2000. No significant atmospheric trends appear to be present at the period 1900–1960. Changes in the atmospheric forcing alone are not capable of explaining fully the difference in the sea level trends for the periods before and after 1960. Steric trends for the period 1960–2000 have also been identified. Their magnitude depends on the depth used for their estimation. Steric trends range between −0.4mm/year for the upper 100m to −2.4mm/year for the whole water column. The residual sea level after the removal of atmospheric and steric effects ranges between 2 and 3.4mm/year at various stations with an associated error bar of 1mm/year. This residual must be accounted for by land movements and incoming signals through the strait of Otranto. The coherence of high frequency sea level signals in the north part of the Adriatic Sea is also analysed for the period 2002–2005 using eight tide gauges. The first empirical orthogonal function contains 71% of the variability indicating that the known coherency at inter-annual and inter-decadal scales extends partly to the higher frequency too. [Copyright &y& Elsevier]

Abstract: The nodal modulation of the diurnal (K 1 and O 1) and semi-diurnal (M 2 and K 2) tidal constituents at the coasts of the Mediterranean Sea and the eastern Atlantic is estimated and its spatial variability mapped. Fourteen hourly tide gauge records each spanning more than 18 years are considered in this analysis. Ten tide gauges are located in the Mediterranean Sea and four in the Bay of Biscay. The nodal modulation of the most energetic tidal constituent (M 2) reaches up to 5cm at the eastern Atlantic coasts, while within the Mediterranean Sea its modulation is in general less than 1.1cm. The largest K 2 nodal modulation found is 3.7cm in the eastern Atlantic coasts. In the Mediterranean Sea, smaller modulation amplitudes, ranging between 0.4 and 1.4cm are found. The K 1 tide constituent has the largest amplitude nodal modulation within the Mediterranean Sea of 1.9cm in the north Adriatic Sea, which is also larger than the modulation of this constituent at the eastern Atlantic coasts. The O 1 tide constituent has the highest amplitude nodal modulation (1.4cm) at the eastern Atlantic coasts. In the Mediterranean Sea the maximum value is 1cm in the north Adriatic Sea. The derived nodal modulations of the diurnal and semi-diurnal constituents follow, in general, the equilibrium tidal theory. The tidal amplitudes for all four components do not indicate significant secular trends for most tide gauges. The tidal phases indicate significant negative trends for all four tidal constituents within the central and eastern Mediterranean Sea. [Copyright &y& Elsevier]

Abstract: Estimates of extreme sea levels and return periods have been based mainly on hourly sampling rates. Technological development has enabled the sampling rates to increase and sampling rates of 5–10min are becoming increasingly common. In this paper we explore the relationship between extreme sea levels and estimated return periods based on hourly and shorter sampling periods in three tide-gauges one at the Atlantic coasts of Spain (Coruña), one in the western Mediterranean (Malaga) and one in the N. Adriatic (Trieste). Significant differences of several centimetres are found in the hourly and 5min extremes. These reflect in significant underestimation of the 50-year return levels which in Trieste reach 38cm. A theoretical relationship between the high and the low sampling rate of extremes is also tested. Thus updated 50-year return levels for the Mediterranean and the coasts of the Iberian peninsula are produced assuming that the differences identified in the various stations generalise to other tide-gauge (hourly) records for which hourly values have been analysed earlier. [Copyright &y& Elsevier]

Investigates the trends in the British Isles mean sea level data measured by tide gages. Analysis of data; Use of sea level indices; Recommendations for the development of tide gage and global positioning system recording.