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Abstract: Sea level trends and inter-annual variability in the Mediterranean Sea for the period 1960–2000 is explored by comparing observations from tide gauges with sea level hindcasts from a barotropic 2D circulation model, and two full primitive equation 3D ocean circulation models, a regional one and the Mediterranean component of a global one,. In the 2D model, 50% of the sea level variance was found to result from the wind and atmospheric pressure forcing. In the 3D models, 20% of the sea level variance was explained by the steric effects. The sea level residuals at the tide gauges locations, calculated by subtraction of the 2D model output from the sea level observations are significantly correlated (r =0.4) with the steric signals from the 3D models. After the removal of the atmospheric and the steric contributions the tide-gauge sea level records indicate a period where sea level was stable (1960–1975) and a period where sea level was rising (1975–2000) with rates in the range 1.1–1.8 mm/yr. A part of the residual trend can be explained by the contribution of local land movements (0.3 mm/yr) while its major part indicates a global signal, probably mass addition, appearing after 1975. [Copyright &y& Elsevier]

Abstract: An Atmosphere-Ocean Regional Climate Model coupled over the Mediterranean basin and forced by river runoff and influxes from the Atlantic Ocean and the Black Sea is used to obtain estimates of sea level rise in the region during the 21st century. Changes in temperature and salinity under the A2 emission scenario, which corresponds to a high level of anthropogenic gas concentration in the atmosphere, are investigated in the different sub-basins and are used to compute the steric sea level change in the region. Significant spatial variability is observed. This model projects a maximum steric sea level rise of 25 cm. The mean steric sea level rise value predicted is around 13 cm with lower values in the eastern Mediterranean and higher values at the western Mediterranean. Coastal sea level rise values are found to be smaller, although this is partly due to the smaller range of vertical integration in the computation of sea level changes. Warming and salinification of the intermediate waters are also predicted to occur simultaneously thus partly compensating each other. The effects of atmospheric pressure changes are added to the steric sea level obtained from the model giving up to 2 mbars and thus also compensating some of the thermal expansion. Circulation changes will in certain areas also add up to 6 cm of sea level rise. There is no predicted seasonal bias in the sea level rise indicating that the seasonal cycles will remain unaffected. These results are derived from a single model and therefore can only been seen as part of a methodological study. Similar investigations should be applied to a range of models and scenarios in order to obtain a range of the future sea level change in the Mediterranean basin and its associated uncertainties. [Copyright &y& Elsevier]

Abstract: The contribution of atmospheric pressure and wind to the XXI century sea level variability in Southern Europe is explored under different climate change scenarios. The barotropic version of the HAMSOM model is forced with the output of the atmospheric ARPEGE model run under scenarios B1, A1B and A2. Additionally, a control simulation forced by observed SST, GHGs and aerosols concentrations for the period 1950–2000 and a hindcast forced by a dynamical downscalling of ERA40 for the period 1958–2001 are also run using the same models. The hindcast results have been validated against tide gauge observations showing good agreement with correlations around 0.8 and root mean square error of 3.2cm. A careful comparison between the control simulation and the hindcast shows a reasonably good agreement between both runs in statistical terms, which points towards the reliability of the modelling system when it is forced only by GHG and aerosols concentrations. The results for the XXI century indicate a sea level decrease that would be especially strong in winter, with trends of up to −0.8±0.1mm/year in the central Mediterranean under the A2 scenario. Trends in summer are small but positive (~0.05±0.04mm/yr), then leading to an increase in the amplitude of the seasonal cycle. The interannual variability also shows some changes, the most important being a widespread standard deviation increase of up to 40%. An increase in the frequency of positive phases of the NAO explains part of the winter negative trends. Also, an increase in the NAO variability would be responsible for the projected increase of the interannual variability of the atmospheric component of sea level. Conversely, the intra-annual variability (1–12months excluding the seasonal cycle) does not show significant changes. [Copyright &y& Elsevier]