Sea level changes along the turkish coasts of the Black Sea, the Aegean Sea and the Eastern Mediterranean (original) (raw)
Internal and external forcing of sea level variability in the Black Sea
Climate Dynamics, 2015
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Response of the Black Sea elevation to intraseasonal sea level changes in the Mediterranean is studied using satellite altimetry data and a linear analytical model. Satellite observations show that the nonseasonal sea level in the Black Sea (η 1) is coherent with that in the Aegean and Marmara Seas (η 0) but lags behind them by 10–40 days at subannual periods. The observed time lag is mainly due to friction that constrains the exchange through the Bosphorus Strait. Using realistic friction and characteristic η 0 forcing in the model, we find that the amplitude of η 1 reaches the amplitude of η 0 at about 1 year period, and the time lag increases from 10 to 22 days at periods 50–250 days. Freshwater fluxes, atmospheric pressure, and to a smaller extent the along-strait wind also influence the Black Sea elevation, but sea level fluctuations in the Mediterranean appear to be the dominant forcing mechanism.
Investigaton of Sea Level Change Along the Black Sea Coast from Tide Gauge and Satellite Altimetry
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2015
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 ...
Effects of the basin dynamics on sea level rise in the Black Sea
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 10 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 15
On the forcing of sea level in the Black Sea
Journal of Geophysical Research, 2004
1] Forcing mechanisms for sea level variability in the Black Sea are investigated in the context of an observed increase in the sea level of this basin by 2.5 mm/yr over the last 60 years. Temperature and salinity variations computed from the Mediterranean Data Archeology and Rescue (MEDAR) data set exhibit significant interdecadal variability. However, the corresponding steric height variation does not show a long-term increase and thus cannot account for the observed change in sea level. The impact of surface freshwater flux (P-E) changes is also investigated using two independent data sets. The first data set, which is based on measurements collected in the basin, can explain most of the sea level variability, with only 0.8 mm/yr remaining unexplained. The second data set, output from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis, is unable to explain any of the observed trend. Potential contributions from changes in river runoff and surface pressure are quantified but found to be minor terms. By comparing the observed salinity changes with the sea level rise and the P-E variability in the first data set, we infer that the P-E variations are the primary cause for the observed sea level rise, while land movements are likely to partly contribute, too. The relationship of Black Sea temperature and salinity variability with corresponding variability in the connected Aegean Sea has also been explored. A significant correlation is found between the salinity of the upper water of the Aegean Sea and the layer between 50 and 300 m in the Black Sea, indicating that the latter layer is a product of the Mediterranean inflow.
Trend Analysis of Sea Levels Along Turkish Coast
2007
Sea level changes can be considered as an indicator of environmental and climate change. Sea level becomes a factor of anxiety to those who fear the possible consequences of the earth warmed as a result of the buildup of greenhouse gases. Despite the cities along coastal lines cover less than five percent of the total surface area of Turkey; their total population is over 30 million with a rapid growing rate. A significant change in sea levels is extremely important to the coastal communities in Turkey. In literature, linear secular trends in annual mean sea level data are calculated as the least squares linear regression to a bivariate distribution of the data value versus year. The length of the time series is recommended to be 60 years or longer which sometimes is permitted to be as low as 25 years. In this study, we use a nonparametric approach to determine trends in sea levels as the available data comprises of rather short record length. At the same time, the nonparametric methods are more tolerable for the short records, computationally simpler and distribution-free. Therefore we investigated trend behaviors in sea level data measured along the Mediterranean, Aegean and Black Sea coasts of Turkey using nonparametric Mann-Kendall test. Annual sea level records, observed for eight typical stations, were used for the purpose of trend detection. As a result, five out of eight stations showed an upward trend as one of them showed a downward trend. No trend was found for the remaining stations. We also fitted a least squared line to quantify rate of change in seal level. Among the stations showing positive trends, the highest rate of change was computed in Trabzon (the Black Sea station) whereas the lowest was computed in Kar ıyaka (the Aegean Sea station). The results confirmed a strong signal of sea level rise at global scale.
Studia Geophysica et Geodaetica, 2012
Sea level trends along the western coasts of Anatolia are investigated during the 1985 -2001 period, quantifying the roles of atmospheric, steric and local land motion contributions to these trends. Tide gauge measurements, temperature/salinity climatologies and GPS data are used in the analyses and the results are compared with the output of a barotropic model forced by atmospheric pressure and wind. Atmospheric and steric contributions to interannual sea level variability are also explored. Two tide gauges collocated with GPS indicate sea level trends of 5.5 to 7.9 mm/yr. After the removal of the atmospheric forcing and steric contribution from sea level records, the resulting trends are 1.2 ± 0.7 mm/yr in Menteş, and 3.2 ± 0.6 mm/yr in Antalya tide gauges which are mostly explained by local land motions estimated from GPS data.
Recent Sea Level Change in the Black Sea from Satellite Altimetry and Tide Gauge Observations
ISPRS International Journal of Geo-Information, 2020
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.
Trend analysis of sea levels along Turkish coasts
wsprod.colostate.edu
Sea level changes can be considered as an indicator of environmental and climate change. Sea level becomes a factor of anxiety to those who fear the possible consequences of the earth warmed as a result of the buildup of greenhouse gases. Despite the cities along coastal lines cover less than five percent of the total surface area of Turkey; their total population is over 30 million with a rapid growing rate. A significant change in sea levels is extremely important to the coastal communities in Turkey. In literature, linear secular trends in annual mean sea level data are calculated as the least squares linear regression to a bivariate distribution of the data value versus year. The length of the time series is recommended to be 60 years or longer which sometimes is permitted to be as low as 25 years. In this study, we use a nonparametric approach to determine trends in sea levels as the available data comprises of rather short record length. At the same time, the nonparametric methods are more tolerable for the short records, computationally simpler and distribution-free. Therefore we investigated trend behaviors in sea level data measured along the Mediterranean, Aegean and Black Sea coasts of Turkey using nonparametric Mann-Kendall test. Annual sea level records, observed for eight typical stations, were used for the purpose of trend detection. As a result, five out of eight stations showed an upward trend as one of them showed a downward trend. No trend was found for the remaining stations. We also fitted a least squared line to quantify rate of change in seal level. Among the stations showing positive trends, the highest rate of change was computed in Trabzon (the Black Sea station) whereas the lowest was computed in Kar ıyaka (the Aegean Sea station). The results confirmed a strong signal of sea level rise at global scale.