scholarly journals Storm surges in the Western Black Sea. Operational forecasting

2000 ◽  
Vol 1 (1) ◽  
pp. 45 ◽  
Author(s):  
G. MUNGOV ◽  
P. DANIEL

The frequency of the storm surges in the Black Sea is lower than that in other regions of the World Ocean but they cause significant damages as the magnitude of the sea level set-up is up to 7-8 times greater than that of other sea level variations. New methods and systems for storm surge forecasting and studying their statistical characteristics are absolutely necessary for the purposes of the coastal zone management. The operational forecasting storm surge model of Meteo-France was adopted for the Black Sea in accordance with the bilateral agreement between Meteo-France and NINMH. The model was verified using tide-gauge observations for the strongest storms observed along the Bulgarian coast over the last 10 years.

2020 ◽  
Vol 9 (3) ◽  
pp. 185 ◽  
Author(s):  
Nevin Avşar ◽  
Şenol Kutoğlu

Global mean sea level has been rising at an increasing rate, especially since the early 19th century in response to ocean thermal expansion and ice sheet melting. The possible consequences of sea level rise pose a significant threat to coastal cities, inhabitants, infrastructure, wetlands, ecosystems, and beaches. Sea level changes are not geographically uniform. This study focuses on present-day sea level changes in the Black Sea using satellite altimetry and tide gauge data. The multi-mission gridded satellite altimetry data from January 1993 to May 2017 indicated a mean rate of sea level rise of 2.5 ± 0.5 mm/year over the entire Black Sea. However, when considering the dominant cycles of the Black Sea level time series, an apparent (significant) variation was seen until 2014, and the rise in the mean sea level has been estimated at about 3.2 ± 0.6 mm/year. Coastal sea level, which was assessed using the available data from 12 tide gauge stations, has generally risen (except for the Bourgas Station). For instance, from the western coast to the southern coast of the Black Sea, in Constantza, Sevastopol, Tuapse, Batumi, Trabzon, Amasra, Sile, and Igneada, the relative rise was 3.02, 1.56, 2.92, 3.52, 2.33, 3.43, 5.03, and 6.94 mm/year, respectively, for varying periods over 1922–2014. The highest and lowest rises in the mean level of the Black Sea were in Poti (7.01 mm/year) and in Varna (1.53 mm/year), respectively. Measurements from six Global Navigation Satellite System (GNSS) stations, which are very close to the tide gauges, also suggest that there were significant vertical land movements at some tide gauge locations. This study confirmed that according to the obtained average annual phase value of sea level observations, seasonal sea level variations in the Black Sea reach their maximum annual amplitude in May–June.


Ocean Science ◽  
2017 ◽  
Vol 13 (3) ◽  
pp. 443-452 ◽  
Author(s):  
Arseny A. Kubryakov ◽  
Sergey V. Stanichny ◽  
Denis L. Volkov

Abstract. Satellite altimetry measurements show that the magnitude of the Black Sea sea level trends is spatially uneven. While the basin-mean sea level rise from 1993 to 2014 was about 3.15 mm yr−1, the local rates of sea level rise varied from 1.5–2.5 mm yr−1 in the central part to 3.5–3.8 mm yr−1 at the basin periphery and over the northwestern shelf and to 5 mm yr−1 in the southeastern part of the sea. We show that the observed spatial differences in the dynamic sea level (anomaly relative to the basin-mean) are caused by changes in the large- and mesoscale dynamics of the Black Sea. First, a long-term intensification of the cyclonic wind curl over the Black Sea, observed in 1993–2014, strengthened divergence in the center of the basin and led to the rise of the sea level in coastal and shelf areas and a lowering in the basin's interior. Second, an extension of the Batumi anticyclone to the west resulted in  ∼  1.2 mm yr−1 higher rates of sea level rise in the southeastern part of the sea. Further, we demonstrate that the large-scale dynamic sea level variability in the Black Sea can be successfully reconstructed using the wind curl obtained from an atmospheric reanalysis. This allows for the correction of historical tide gauge records for dynamic effects in order to derive more accurate estimates of the basin-mean sea level change in the past, prior to the satellite altimetry era.


2016 ◽  
Vol 7 (1) ◽  
pp. 50-55 ◽  
Author(s):  
Nevin B. Avsar ◽  
Shuanggen Jin ◽  
Hakan Kutoglu ◽  
Gokhan Gurbuz

2020 ◽  
pp. 105-114
Author(s):  
Yu. S. Tuchkovenko ◽  
O. S. Matygin ◽  
V. Yu. Chepurna

Increasing the draught of ships that may be accepted by ports for loading at their loading berths is one of the main tasks aimed at development and freight turnover enhancement of sea trade ports located in Odesa Region of the north-western part of the Black Sea (cities of Chornomorsk, Odesa and Pivdennyi). An operational forecasting of short-term sea level fluctuations caused by storm winds presents a critical task for ensuring safe navigation across the ports’ water area and approach channels. The article is devoted to analysing and discussing the results of tests of a simplified 2D hydrodynamic model designed for forecasting such phenomena as upsurge and downsurge of the sea level caused by storm winds in the vicinity of sea ports in Odesa Region of the north-western part of the Black Sea. Spatio-temporal variability of wind conditions at the sea-to-atmosphere boundary was set based on the data retrieved from a 10-day synoptic forecast using global atmospheric prediction model GFS (Global Forecast System). The study analyses the results of forecast of significant (the ones exceeding 30 cm) short-term sea level drops and rises at the ports which were observed in 2016, 2017 and 2020. It was established that, in case of use of the GFS forecast data, the pattern of sea level denivellations caused by storm winds and their amplitude in the majority of events start approximating to the observed values provided the forecast has a 4-day lead time. Therefore the accuracy of wind conditions variability forecast with application of the GFS model having a longer lead advance time is not sufficient for forecasting the sea level fluctuations caused by storm winds.  The study made it possible to get an acceptable equivalence between the values of sea level denivellation amplitudes which were forecast with a 1-to-3-day lead time and the ones observed afterwards. In particular, when the forecast lead time is equal to »2 days, in relation to the expected storm conditions, the average absolute error for the forecast of sea level fluctuations amplitude constituted 7-8 cm, while its permissible value was defined as 15 cm, and the average relative error – 16-18%. It allowed making a conclusion that a hydrodynamic model option, applied alongside with the forecasting information on wind conditions variability retrieved with the help of the GFS weather prediction model, may be used for operational forecasting of short-term sea level fluctuations caused by storm winds with the forecast lead time of up to 4 days.


Author(s):  
N. B. Avsar ◽  
S. H. Kutoglu ◽  
S. Jin ◽  
B. Erol

In this study, we focus on sea level changes along the Black Sea coast. For this purpose, at same observation period the linear trends and the components of seasonal variations of sea level change are estimated at 12 tide gauge sites (Amasra, Igneada, Trabzon-II, Sinop, Sile, Poti, Batumi, Sevastopol, Tuapse, Varna, Bourgas, and Constantza) located along the Black Sea coast and available altimetric grid points closest to the tide gauge locations. The consistency of the results derived from both observations are investigated and interpreted. Furthermore, in order to compare the trends at the same location, it is interpolated from the trends obtained at the altimetric grid points in the defined neighbouring area with a diameter of 0.125° using a weighted average interpolation algorithm at each tide gauge site. For some tide gauges such as Sevastopol, Varna, and Bourgas, it is very likely that the trend estimates are not reliable because the time-spans overlapping the altimeter period are too short. At Sile, the long-term change for the time series of both data types do not give statistically significant linear rates. However, when the sites have long-term records, a general agreement between the satellite altimetry and tide gauge time series is observed at Poti (~20 years) and Tuapse (~18 years). On the other hand, the difference of annual phase between satellite altimetry and tide gauge results is from 1.32° to 71.48°.


2021 ◽  
Author(s):  
Oleksii Batyrev ◽  
Olga Andrianova ◽  
Radomir Belevich ◽  
Michael Skipa

<p>Coastal zone research is becoming increasingly important because the impact of climate change is most significant here. The state of coastal regions is determined by the variability in three contact media (geological, water, and air). Evaluation of level changes on the coasts of various parts of the World Ocean (the Mediterranean, Black, Baltic and North Seas, and the Atlantic coasts in Brazil and France) over a long period of time shows various fluctuations with an upward trend in recent decades.</p><p>To highlight the factors that determine the seashores' level fluctuations, three contact media parameters were considered on the example of the western part of the Black Sea. Calculations, analysis, and comparison of trends in the variability of hydrometeorological characteristics (air and water temperatures, precipitation, and river discharge) and sea level over a period of more than 100 years have been carried out.</p><p>To assess the intensity of fluctuations of the coastal land along the western coast of the Black Sea, the series of level heights were considered at 6 Ukrainian stations: Vylkove, Chornomorsk (Ilyichevsk), Odesa-port, port Yuzhne, Ochakiv and Sevastopol (partially used as a benchmark), at 2 stations on the Romanian coast: Constanta and Sulina, and 2 stations on the Bulgarian coast: Burgas and Varna. Estimates of the dynamics of the land for the stations of this region's coastal zone for more than a 100-year period are calculated, and it is shown in which way changes in sea level are a consequence of the processes occurring in the coastal land and at the bottom.</p><p>Comparison of the years with extreme fluctuations in the sea level with the years of the global El Niño phenomenon showed that one of the causes of the observed disturbances in the water and air environments is the distant manifestations of this phenomenon.</p><p>Level fluctuations, both in the Black Sea and in the World Ocean, are synchronous at low-frequency scales (their period is more than 5 years) since global climatic processes on our planet influence them; short-term fluctuations are distinguished by regional features and are created under the influence of local factors (tectonic, geophysical, hydrostatic, etc.).</p><p>Modeling and predicting changes in the coastal zone of various parts of the World Ocean requires continuation of systematic observations of sea-level fluctuations, hydrometeorological characteristics, and seismic conditions in regions with the longest data series; it's crucial for the Black Sea as well for the Mediterranean, Baltic, North Seas, and Atlantic shores.</p>


2020 ◽  
Author(s):  
Stephen Outten ◽  
Tobias Wolf ◽  
Fabio Mangini ◽  
Linling Chen ◽  
Jan Even Nilsen

<p>Flooding events pose an ever increasing threat in a warming world. Safety standards for buildings and infrastructure are often based on past observations of local sea level, as measured by tide gauges and remote sensing systems. However, sea level at a given location is not an isolated property and is determined by a combination of factors. For extreme sea level events, there are two factors that of particular importance: the astronomical tide, and storm surges. In this work, we analysed measurements from 21 stations in the Norwegian tide gauge network, disentangling the factors contributing to the previously observed extreme events.</p><p>By separating the observed sea level into a tidal component and a storm surge component, we found that in many cases the observed extreme sea level events were caused by an extreme storm surge coinciding with only a moderate tide, or an extreme tide coinciding with only a moderate storm surge. This raises the possibility of a ‘super-flooding’ event, where an extreme storm surge may occur with an extreme tide. Even in the short records examined in this study (less than 40 years), the combination of the highest observed tide with the highest observed storm surge would greatly exceed in the 1000-year return level event at many locations. This is often used as a national standard for critical infrastructure.  </p><p>We further complement the work by analysing the storm tracks close to Norway. By relating the storm surges with the individual storms giving rise to them, we found that many storm surges during extreme sea level events were related to cyclones of only moderate intensity. Combined with the previous findings, this work suggests the need to assess extreme sea level return values for future construction and infrastructure planning as the result of a multi-variable system. This is in contrast to basing such assessments on the single variable of observed sea level as it is done today.</p>


2016 ◽  
Author(s):  
A. A. Kubryakov ◽  
S. V. Stanichny ◽  
D. L. Volkov

Abstract. Satellite altimetry measurements show that magnitude of the Black Sea level trends is spatially uneven. While the basin-averaged sea level was increasing at a rate of 3.15 mm/year from 1993 to 2014, the sea level rise varied from 0.15–2.5 mm/year in the central part to 3.5–3.8 mm/year in coastal areas and 5 mm/year in the southwestern part of the sea. These differences are caused by changes in the large- and mesoscale circulation of the Black Sea. A long-term increase of the cyclonic wind curl over the basin from 1979 to 2014 strengthened divergence in the center of the Black Sea that led to an increase of sea level near the coast and a decrease in the center of the basin. Changes in the distribution and intensity of mesoscale eddies caused the formation of the local extremes of sea level trend. The variability of the dynamic sea level (DSL) – the difference between the local and the basin-averaged sea levels – contributes significantly (up to ~ 50 % of the total variance) to the seasonal and interannual variability of sea level in the basin. The DSL variability in the Black Sea depends strongly on the basin-averaged wind curl and is well reconstructed using the ERA-Interim winds from 1979 to present, including the time when altimetry data was unavailable. The reconstruction can be used to correct historical tide gauges data for dynamic effects, which are usually neglected in the analysis of the Black Sea tide gauge records.


Author(s):  
N. B. Avsar ◽  
S. H. Kutoglu

<p><strong>Abstract.</strong> Potential sea level rise poses a significant threat to low-lying areas. Considering present and future of coastal areas, scientific study of sea level rise is an essential for adapting to sea level extremes. In this study, the relative sea level change in the Black Sea were investigated using data of 12 tide-gauge and 6 GNSS stations. Results generally indicated sea level rise along the Black Sea coast. Only at Bourgas tide-gauge station, a sea level fall was detected. A significant sea level change were not determined at Sinop tide-gauge station. On the other hand, at some stations such as Poti and Sile, ground subsidence contribution to relative sea level changes were observed.</p>


Author(s):  
Nikolay Esin ◽  
Nikolay Esin ◽  
Vladimir Ocherednik ◽  
Vladimir Ocherednik

A mathematical model describing the change in the Black Sea level depending on the Aegean Sea level changes is presented in the article. Calculations have shown that the level of the Black Sea has been repeating the course of the Aegean Sea level for the last at least 6,000 years. And the level of the Black Sea above the Aegean Sea level in the tens of centimeters for this period of time.


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