Map of the Mediterranean Sea level linear trends over the period (1993-2017). Seasonal signal removed, glacial-isostatic adjustment (GIA) applied. Location of the tide gauge (TG) stations used in this study (numbered black circles according to Table 1), and of the corresponding nearest altimeter grid point (white circles). The solid black line defines the separation between the different basins

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... remove high-frequency signals less than 1-year, we computed running averages with a 1-year window and excluded the first and last 6 months of data in each time series to avoid edge effects. Figure 3 shows the TG locations numbered from west to east along the coast according to Table 1. ...

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... the linear part, but deviation from this hypothesis limits its reliability. Thus, to account for uncertainties on the regression coefficient (slope), the linear trend is given by (trend = slope ± l). In the current study, we divide the Mediterranean Sea into five sub-basins (W. Mediterranean, Adriatic, Ionian, Aegean, and Levantine) as shown in Fig. 3. This division is based on the regional differences in the sea level variability and trends. Similar divisions have been used for the Mediterranean Sea by Tsimplis and Rixen ...

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... contours in Fig. 3 depict the altimetry derived sea level linear trends after the seasonal cycle and the GIA correction are removed. The GIA correction to altimetry data (dGeoid) is negative in the whole Mediterranean Sea, it ranges between -0.1 and -0.35 mm/year, with a mean value of -0.2 mm/ year for the whole Basin. The absolute sea level trends show ...

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... Mov.Avg.NAO Inter-Annual Variability and Trends of Sea Level and Sea Surface Temperature Figure 11 shows the spatial pattern of the SST linear trends over the 1993-2017 period, after the seasonal cycle was removed. The geographical distribution of the linear SST trend is like the spatial distribution observed in Fig. 3 for the linear sea level trend. The SST trend exhibits different behavior in the eastern and western sub-basins. Nonetheless, the SST trend map appears smoother everywhere than the sea level trend. A higher positive value is evident in the Levantine basin, with values up to 0.06 °C/year in the Cretan Arc and in the west of Cyprus, also ...

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... first three EOF modes of SLA explain about 56.2% of the total deseasoned variance of the data as shown in Fig. 13. The other EOFs fail a significant test based on a Monte Carlo technique (Overland and Preisendorfer 1982). The first mode explains 44.6% of the total deseasoned variance. The spatial pattern of this mode shows an in-phase oscillation of the whole basin, i.e. an in-phase heating or cooling implying an increase or decrease of sea level ...

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... first three EOF modes of SSTA explain about 68.1% of the total deseasoned variance of the data as shown in Fig. 13. The first mode is explaining 40.7% of the total deseasoned variance. The spatial pattern has shown positive values throughout the whole Mediterranean Sea, indicating an in-phase oscillation of the whole basin around the steady-state mean. The highest SSTA variability was observed over the central part of the Mediterranean Sea with ...

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... seasonal cycle dominates (Fenoglio-Marc 2002). Since SST is an indicator of thermosteric variations, the high correlation between SLA and SSTA in the Aegean and Levantine basins implies that the inter-annual linear sea level trend has been largely driven by thermosteric effects. Comparing the linear trend in sea level and sea surface temperature (Figs. 3 and 11), we see a general increase in sea level in the Mediterranean Sea, where the SST rose in general, and a drop in sea level in the Ionian Sea and Ierapetra gyre, where the SST dropped (with the exception of the western Mediterranean). In view of the high spatial correlation between SLA and SST linear trends in the Eastern Mediterranean, ...

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... sea level signal from both altimetry and tide gauges revealed extremely large fluctuations in the Figure 13 The first three EOF/PC (spatial variation/temporal variation) modes of the inter-annual variability for SLA (left) and SSTA (right) in the Mediterranean Sea during 1993-2017 (trend and seasonal cycles have been removed) Figure Inter-Annual Variability and Trends of Sea Level and Sea Surface Temperature extended winters (December-March) of 2009-2010 and 2010-2011, which occurred throughout a strong negative phase of the NAO index, in agreement with Landerer and Volkov (2013). This event was characterized by a non-steric fluctuations, because of mass transport through the Strait of Gibraltar is mainly driven by wind according to Tsimplis et al. (2013). ...

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... and SSTA are strongly correlated at seasonal scales in the whole Mediterranean Sea, except over the Adriatic Sea. After the seasonal cycle has been removed from both time series, the correlations are strongly decreasing over the whole basin, except in the Aegean and Levantine Basins. The comparison between sea level and SST linear trend maps (see Figs. 3 and 11) showed that both sea level and SST are either increasing (or decreasing) simultaneously in the eastern Mediterranean. These suggests that the thermosteric effect, can have a strong influence on sea level change in the eastern Mediterranean ...