Spanning over a century, a traditional way to monitor sea level variability by tide gauges is – in combination with modern observational techniques like satellite altimetry – an inevitable ingredient in sea level studies over the climate scales and in coastal seas. The development of the instrumentation, remote data acquisition, processing and archiving in last decades allowed for extending the applications towards a variety of users and coastal hazard managers. The Mediterranean and Black seas are an example for such a transition – while having a long tradition for sea level observations with several records spanning over a century, the number of modern tide gauge stations are growing rapidly, with data available both in real-time and as a research product at different time resolutions. As no comprehensive survey of the tide gauge networks has been carried out recently in these basins, the aim of this paper is to map the existing coastal sea level monitoring infrastructures and the respective data availability. The survey encompasses description of major monitoring networks in the Mediterranean and Black seas and their characteristics, including the type of sea level sensors, measuring resolutions, data availability and existence of ancillary measurements, altogether collecting information about 236 presently operational tide gauge stations. The availability of the Mediterranean and Black seas sea level data in the global and European sea level repositories has been also screened and classified following their sampling interval and level of quality-check, pointing to the necessity of harmonization of the data available with different metadata and series at different repositories. Finally, an assessment of the networks’ capabilities for their usage in different sea level applications has been done, with recommendations that might mitigate the bottlenecks and assure further development of the networks in a coordinated way, being that more necessary in the era of the human-induced climate changes and the sea level rise.
The recurrence of extreme wind waves in the Kara Sea strongly influences the Arctic climate change. The period 2000–2010 is characterized by significant climate warming, a reduction of the sea ice in the Arctic. The main motivation of this research to assess the impact of climate change on storm activity over the past 39 years in the Kara Sea. The paper presents the analysis of wave climate and storm activity in the Kara Sea based on the results of numerical modeling. A wave model WAVEWATCH III is used to reconstruct wind wave fields for the period from 1979 to 2017. The maximum significant wave height (SWH) for the whole period amounts to 9.9 m. The average long-term SWH for the ice-free period does not exceed 1.3 m. A significant linear trend shows an increase in the storm wave frequency for the period from 1979 to 2017. It is shown that trends in the storm activity of the Kara Sea are primarily regulated by the ice. Analysis of the extreme storm events showed that the Pareto distribution is in the best agreement with the data. However, the extreme events with an SWH more than 6‒7 m deviate from the Pareto distribution.
Abstract Tides in the Adriatic Sea are anomalously strong in comparison with most of other parts of the Mediterranean Sea. Consequently, tides play a fundamental role in the hydrodynamics of this sea and in the formation of destructive floods in its northernmost part. The resonant character of the Adriatic tides is evident, but the exact mechanism of their formation has never been thoroughly examined. In the present study, we used multidecadal tide gauge data from 10 stations located along the basin's coastline to examine the spectral properties of the Adriatic Sea and to provide high‐resolution tidal analysis. Our results demonstrate that both diurnal and semidiurnal tidal harmonics are resonantly amplified due to the proximity of tidal periods to the periods of the fundamental (21.5 hr) and first (10.9 hr) Adriatic eigen modes, respectively. The constructed resonance models were found to closely describe specific features of the observed tides in the Adriatic Sea, including both major and minor harmonics, and therefore help to explain the dominant physical mechanism driving the floods in the northernmost part of the basin, including the Venice Lagoon.
Abstract. Recurrence of extreme wind waves in the Kara Sea strongly influences the Arctic climate change. The paper presents the analysis of wave climate and storm activity in the Kara Sea based on the results of numerical modeling. A third-generation wave model WaveWatchIII is used to reconstruct wind wave fields on an unstructured grid with a spatial resolution of 15–20 km for the period from 1979 to 2017. The mean and maximum wave heights, wavelengths and periods are calculated. The maximum significant wave height (SWH) for the whole period amounts to 9.9 m. The average long-term SWH for the ice-free period does not exceed 1.3 m. The seasonal variability of the wave parameters is analyzed. The interannual variability of storm waves recurrence with different thresholds (from 3 to 7 m) was calculated. A significant linear trend shows an increase in the storm wave frequency for the period from 1979 to 2017. A double growth in the reccurence was observed for cases with an SWH more than 3–5 m from 1979 to 2017. The local maximum of the storm waves more than 3–4 m was observed in 1995, and the minimum in 1998. The maximum value (four cases) of the number of storms with an SWH threshold 7 m is registered in 2016. The frequency of wind speeds and ice conditions contributing to the storm waves formation were analyzed. It is shown that trends in the storm activity of the Kara Sea are primarily regulated by the ice. If the ice cover decreases in the southern part of the sea that leads to the increase of the number of events only with SWH threshold more than 3–4 m. If in the entire sea the ice cover decreases that leads already to increase of the extreme storms. The frequency of strong and long-term winds has high interannual variability and a weak positive trend. The analysis of distribution functions of the storm events with an SWH more than 3 m was carried out. Six different sectors of the Kara Sea were analyzed to reveal spatial differences. A comparison of the different distribution laws showed that the Pareto distribution is in the best agreement with the data. Up to 99 % of the points are described by this distribution. However, the extreme events with an SWH more than 6–7 m deviate from the distribution, and their probability is approximately twice as less as that predicted by the Pareto distribution. Presumably, this deviation is caused by the combined impact of rare wind speed frequencies and anomalies of the sea ice conditions.
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