A new tide model for the Mediterranean Sea based on altimetry and tide gauge assimilation

Abstract

The tides for the Mediterranean Sea are described through a high resolution model (MEDI10) developed by assimilation of tide-gauge data and T/P data into a barotropic ocean tide model. Tidal parameters from 56 coastal tide-gauge stations around the Mediterranean for eight principal constituents: M2, S2, N2, K2, K1, O1, P1 and Q1 and from 20 stations for M2, S2, K1, O1 are included in the model. TOPEX/Poseidon data with all corrections applied except for the ocean tides and bathymetry from TOPO 13.1 were used for development of the model. Numerical experiments were carried out for the estimation of the friction velocity and of the decorrelation length scale. The experiments related to the friction velocity showed that the use of spatially varying friction velocity, estimated as a function of position in the model domain, gives better results than a constant value. The experiments related to the estimation of the decorrelation length suggest that the results are not sensitive for lengths close to ten times the length of the grid cell. The assessment of the model is based on ten tide-gauge observations that are not used for the assimilation. Comparisons were carried out with contemporary published global or regional models. The final solution is computed using 76 selected coastal tide-gauge stations. The comparison between the observed and the model constituents results in a Root Sum of Squares (RSS) equal to 1.3 cm.

Estimating Lagrangian transport blending drifters with HF radar data and models: Results from the TOSCA experiment in the Ligurian Current (North Western Mediterranean Sea)

“…A boundary current like the one considered here might have longer correlation times and therefore higher forecasting skills than for instance local coastal flows in gulfs or flows with large tidal fluctuations. In this case, tidal currents are extremely low (generally lower than 10 À3 m/s) with amplitudes among the smallest in the whole Mediterranean Sea (Albérola et al, 1995b;Arabelos et al, 2011). Even though in this paper tidal effects have been disregarded for the aforementioned reasons, we also envision possible applications of LAVA to marine basins where high frequency current variability is large.…”

“…The method implies of course a simplified representation of the current field, but its testing is relevant for operational situations, to verify whether or not some guidance can be provided at least for the first few hours. It is important to keep in mind that the Mediterranean Sea has small tidal ranges being connected to the Atlantic Ocean through a narrow entrance (the Gibraltar Strait) (Arabelos et al, 2011;Pugh, 1987). For this reason, relatively slowly varying mesoscale flows are expected to be more relevant than tidal fluctuations.…”

High-frequency sea level oscillations in the Mediterranean and their connection to synoptic patterns

“…These conditions are conducive to generating and trapping atmospheric gravity waves in the lower troposphere (Lindzen and Tung, 1976), which can, through rapid changes in air pressure and wind at the sea surface, generate long ocean waves over the shelf (Šepić et al, 2009a). A metre-high sea level oscillation in a tsunami frequency band hitting a coastal area may be particularly important in low-tidal seas such as the Mediterranean, where the tides range from 10 to 30 cm in most of the basin (Tsimplis et al, 1995;Arabelos et al, 2011). Moreover, extreme storm surges are typically no higher than a metre and normally reach approximately half a metre .…”

Block Approach to the Simulation of Circulation and Tides in the Black Sea

“…Batumi anticyclone is not clearly reproduced, due to the rough set of the atmospheric forcing spatial distribution according to ERA-Interim reanalysis data Adding to the model the tide-generating potential block. In general, the current global tide models can be divided into three groups: the hydrodynamic, empirical and hydrodynamic with monitoring data assimilation (mareographs and satellite altimetry) [14,23,24]. Forecast of tides in the Black Sea applying the latter two types of models appears to be complicated due to the lack of continuous series of observations.…”