Transformations in the Caspian Sea ecosystem under the fall and rise of the sea level

Oceanology ◽  
2010 ◽  
Vol 50 (4) ◽  
pp. 488-497 ◽  
Author(s):  
V. V. Sapozhnikov ◽  
N. V. Mordasova ◽  
M. P. Metreveli
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
The Caspian Sea

scholarly journals Seasonal variability of the Caspian Sea three-dimensional circulation, sea level and air-sea interaction

Ocean Science ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 311-329 ◽  
Author(s):  
R. A. Ibrayev ◽  
E. Özsoy ◽  
C. Schrum ◽  
H. İ. Sur
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Caspian Sea ◽  
Seasonal Cycle ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Sea Surface ◽  
Coastal Currents ◽  
The Caspian Sea ◽  
Sea Surface Topography

Abstract. A three-dimensional primitive equation model including sea ice thermodynamics and air-sea interaction is used to study seasonal circulation and water mass variability in the Caspian Sea under the influence of realistic mass, momentum and heat fluxes. River discharges, precipitation, radiation and wind stress are seasonally specified in the model, based on available data sets. The evaporation rate, sensible and latent heat fluxes at the sea surface are computed interactively through an atmospheric boundary layer sub-model, using the ECMWF-ERA15 re-analysis atmospheric data and model generated sea surface temperature. The model successfully simulates sea-level changes and baroclinic circulation/mixing features with forcing specified for a selected year. The results suggest that the seasonal cycle of wind stress is crucial in producing basin circulation. Seasonal cycle of sea surface currents presents three types: cyclonic gyres in December–January; Eckman south-, south-westward drift in February–July embedded by western and eastern southward coastal currents and transition type in August–November. Western and eastern northward sub-surface coastal currents being a result of coastal local dynamics at the same time play an important role in meridional redistribution of water masses. An important part of the work is the simulation of sea surface topography, yielding verifiable results in terms of sea level. The model successfully reproduces sea level variability for four coastal points, where the observed data are available. Analyses of heat and water budgets confirm climatologic estimates of heat and moisture fluxes at the sea surface. Experiments performed with variations in external forcing suggest a sensitive response of the circulation and the water budget to atmospheric and river forcing.

scholarly journals Features of seasonal changes of the Caspian Sea level

2019 ◽  
Author(s):  
E.S. Safarov ◽  
◽  
J.-F. Cretaux ◽  
R.M. Mammadov ◽  
A. Arsen ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Seasonal Changes ◽  
The Caspian Sea

Tsunami Hazard of the Caspian Sea

2021 ◽  
Author(s):  
Alisa Medvedeva ◽  
Igor Medvedev
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Tsunami Hazard ◽  
Seismic Sources ◽  
Deterministic Approach ◽  
The Caspian Sea ◽  
Tsunami Waves ◽  
The Mean ◽  
Run Up ◽  
Sea Coast

<p>A regional model of tsunami seismic sources in the zone of the Main Caucasian thrust has been developed. The parameters of probable models of seismic sources and their uncertainties were estimated based on the available data on historical earthquakes and active faults of the region. The scenario modeling technique was used for the tsunami zoning of the Caspian Sea coast. The time period covered by the model catalog of earthquakes used to calculate the generation and propagation of tsunamis is about 20 000 years, which is longer than the recurrence periods of the strongest possible earthquakes. The recurrence graphs of the calculated maximum tsunami heights for the entire sea coast were plotted. On their basis, the maximum heights of tsunami waves on the coast were calculated with recurrence periods of 250, 500, 1000 and 5000 years and the corresponding survey maps of the tsunami zoning of the Caspian Sea were created. The algorithm for calculating the tsunami run-up on the coast is improved, taking into account the residual (postseismic) displacements of the bottom and land relief. Estimates of tsunami hazard for the coast near the city of Kaspiysk were carried out: within the framework of the deterministic approach, the maximum wave heights and run-up distance were calculated. It is shown that the deterministic approach slightly overestimates the maximum heights of tsunami waves with certain return periods. It is shown that changes in the mean sea level can affect the features of the propagation of tsunami waves in the Caspian Sea. Thus, at an average sea level of -25-26 m, the Kara-Bogaz-Gol Bay is linked with the entire sea through a narrow strait. It leads to the propagation of tsunami waves into the water area of the bay and a decrease in wave height on the eastern coast of the sea. When the mean sea level decreases below -27 m, the positive depths in the strait disappear and water exchange through the strait stops, and the wave height in this part of the sea increases.</p>

Caspian Sea-level changes at the end of Little Ice Age and its impacts on the avulsion of the Gorgan River : a multidisciplinary case study from the southeastern flank of the Caspian Sea

2014 ◽  
pp. 145-155 ◽  
Author(s):  
Abdolmajid Naderi Beni ◽  
Hamid Lahijani ◽  
Morsen Pourkerman ◽  
Rahman Jokar ◽  
Muna Hosseindoust ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Little Ice Age ◽  
Ice Age ◽  
Sea Level Changes ◽  
The Caspian Sea

scholarly journals Impact of the European Russia drought in 2010 on the Caspian Sea level

2012 ◽  
Vol 16 (1) ◽  
pp. 19-27 ◽  
Author(s):  
K. Arpe ◽  
S. A. G. Leroy ◽  
H. Lahijani ◽  
V. Khan
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Analysis Data ◽  
Reanalysis Data ◽  
European Russia ◽  
Severe Drought ◽  
The Caspian Sea ◽  
Volga River ◽  
The Impact

Abstract. The hydrological budgets of the Volga basin (VB) and the Caspian Sea (CS) have been analysed. The components of the water balance for the CS were calculated for the period 1993 to 2010 with emphasis on summer 2010 when a severe drought developed over European Russia. A drop in precipitation over the VB in July 2010 occurs simultaneously with a decrease in evaporation for the same area, an increase of evaporation over the CS itself and a drop of the Caspian Sea level (CSL). The drop in the precipitation over the VB cannot lead to an instantaneous drop of the CSL because the precipitated water needs some months to reach the CS. The delay is estimated here to be 1 to 3 months for excessive precipitation in summer, longer for deficient precipitation and for winter cases. However, the evaporation over the CS itself is considered to be responsible for a simultaneous drop of the CSL from July to September 2010. The impact on the CSL from the precipitation deficit over the VB occurs in the months following the drought. The water deficit from July to September 2010 calculated from the anomalous precipitation minus evaporation over the VB would decrease the CSL by 22 cm, of which only 2 cm had been observed until the end of September (observed Volga River discharge anomaly). So the remaining drop of 20 cm can be expected in the months to follow if no other anomalies happen. In previous studies the precipitation over the VB has been identified as the main cause for CSL changes, but here from a 10 cm drop from beginning of July to end of September, 6 cm can be directly assigned to the enhanced evaporation over the CS itself and 2 cm due to reduced precipitation over the CS. Further periods with strong changes of the CSL are also investigated, which provide some estimates concerning the accuracy of the analysis data. The investigation was possible due to the new ECMWF interim reanalysis data which are used to provide data also for sensitive quantities like surface evaporation and precipitation. The comparison with independent data and the consistency between such data for calculating the water budget over the CS gives a high confidence in the quality of the data used. This investigation provides some scope for making forecasts of the CSL few months ahead to allow for mitigating societal impacts.

scholarly journals <i>Lingulodinium machaerophorum</i> expansion over the last centuries in the Caspian Sea reflects global warming

2012 ◽  
Vol 9 (11) ◽  
pp. 16663-16704
Author(s):  
S. A. G. Leroy ◽  
H. A. K. Lahijani ◽  
J.-L. Reyss ◽  
F. Chalié ◽  
S. Haghani ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Global Climate ◽  
Sediment Cores ◽  
Sea Surface ◽  
Sea Level Changes ◽  
The Caspian Sea ◽  
Sea Level Fluctuations ◽  
Marine Surface ◽  
A Minor

Abstract. We analysed dinoflagellate cyst assemblages in four short sediment cores, two of them dated by radionuclides, taken in the south basin of the Caspian Sea. The interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples. A sharp increase in the biomass of the dinocyst occurs after 1967, especially owing to Lingulodinium machaerophorum. Considering nine other cores covering parts or the whole of Holocene, this species started to develop in the Caspian Sea only during the last three millennia. By analysing instrumental data and collating existing reconstructions of sea level changes over the last few millennia, we show that the main forcing of the increase of L. machaerophorum percentages and of the recent dinocyst abundance is global climate change, especially sea surface temperature increase. Sea level fluctuations likely have a minor impact. We argue that the Caspian Sea has entered the Anthropocene.

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