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.

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.

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

High-resolution assessment of the Valgu event: conodont diversity and δ18Ophos during the early Telychian (Silurian) in the Baltic Basin

2020 ◽  
Author(s):  
Monica Alejandra Gomez Correa ◽  
Emilia Jarochowska ◽  
Peep Männik ◽  
Axel Munnecke ◽  
Michael Joachimski
Keyword(s):  
Carbon Cycle ◽  
Sea Level ◽  
Global Climate ◽  
Baltic Basin ◽  
Sea Level Fluctuations ◽  
Core Section ◽  
Storm Wave ◽  
The Baltic ◽  
A Minor ◽  
The Impact

&lt;p&gt;The influence of global climate and oceanographic system dynamics over biological patterns throughout Earth&amp;#8217;s history is one of the main concerns in paleobiology. Periods that record changes in biodiversity of various magnitude are of particular interest in this field. Previous studies of major Silurian bioevents (e.g. Ireviken, Mulde and Lau) suggest that these events affected different faunas and have been correlated with positive carbon isotope (&amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;carb&lt;/sub&gt;) excursions and positive shifts in oxygen isotopes (&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;phos&lt;/sub&gt;) ratios, suggesting there was a disturbance in the carbon cycle, a drop in temperature, and potential glaciations. However, the impact of the biological events has not been fully assessed, and the influence of climate change remains unclear.&lt;/p&gt;&lt;p&gt;Here, we focus on the Valgu event, a minor episode of proposed environmental and faunistic changes in the early Telychian, which has been recognized in Baltica and Laurentia paleocontinents by changes in conodont succession and a positive excursion in &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;carb&lt;/sub&gt;. In this study, we assess a limestone-marl alternation core section in Estonia deposited below the storm wave base during the Valgu event. We test for a substantial decrease in the biodiversity of conodont communities, for extent perturbation in the carbon cycle, manifest in a positive &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;carb&lt;/sub&gt; excursion, and an abrupt positive &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;phos&lt;/sub&gt; shift, which might be indicative of rapid cooling and a rapid sea-level fall typical for glacio-eustatic cycles. To this aim, we measured bulk-rock &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;carb&lt;/sub&gt; as well as &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;phos&lt;/sub&gt; in monogeneric conodont samples and analyzed the conodont diversity from the event interval.&lt;/p&gt;&lt;p&gt;The lower part of the investigated section is characterized by shallow-water bioclastic limestones containing green algae. On top of this facies, a pronounced hardground indicates a gap in deposition and marks the boundary between the bioclastic limestones and the overlying sediments composed of nodular limestones and marls, which were deposited below the storm wave base. They show a positive carbon shift of ca. 1.4 &amp;#8240; during the Valgu interval, but no indication of an extreme change in the conodont biodiversity is evident. Likewise, the &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;phos&lt;/sub&gt; in conodonts remains constant in the section, arguing against cooling or glacially-driven sea-level fluctuations as drivers for the observed changes.&lt;/p&gt;

scholarly journals Caspian Sea Level changes based on Satellite altimetry

2021 ◽  
Author(s):  
Omid Memarian Sorkhabi
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Satellite Altimetry ◽  
Sea Water ◽  
Sea Level Change ◽  
High Accuracy ◽  
Research Data ◽  
Sea Level Changes ◽  
The Caspian Sea ◽  
Level Change

Abstract Today, despite the satellite altimetry, it is possible to determine the average sea level and determine the sea level change with high accuracy. In this research, data from 1992-2017 TOPEX / Poseidon, Jason1, OSTM and Jason3 altimeter satellites in the Caspian Sea have been used. The results show that every year the average of 75 mm of the Caspian Sea water level decreases and the downward trend.

scholarly journals Caspian Sea Level changes based on Satellite altimetry

2021 ◽  
Author(s):  
Omid Memarian Sorkhabi
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Satellite Altimetry ◽  
Sea Water ◽  
Sea Level Change ◽  
High Accuracy ◽  
Research Data ◽  
Sea Level Changes ◽  
The Caspian Sea ◽  
Level Change

Abstract Today, despite the satellite altimetry, it is possible to determine the average sea level and determine the sea level change with high accuracy. In this research, data from 1992-2017 TOPEX / Poseidon, Jason1, OSTM and Jason3 altimeter satellites in the Caspian Sea have been used. The results show that every year the average of 75 mm of the Caspian Sea water level decreases and the downward trend.

scholarly journals Holocene vegetation history and sea level changes in the SE corner of the Caspian Sea: relevance to SW Asia climate

2013 ◽  
Vol 70 ◽  
pp. 28-47 ◽  
Author(s):  
Suzanne A.G. Leroy ◽  
Ata A. Kakroodi ◽  
Salomon Kroonenberg ◽  
Hamid K. Lahijani ◽  
Habib Alimohammadian ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Vegetation History ◽  
Sea Level Changes ◽  
The Caspian Sea ◽  
And Sea Level

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

2009 ◽  
Vol 6 (3) ◽  
pp. 1913-1970 ◽  
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. 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.

Intraannual and interannual variability of storm surges in the North Caspian Sea

2020 ◽  
Vol 3 ◽  
pp. 42-57
Author(s):  
A.V. Pavlova ◽  
◽  
V.S. Arkhipkin ◽  
S.A. Myslenkov ◽  
◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Storm Surges ◽  
Western Coast ◽  
Coastal Zones ◽  
The Caspian Sea ◽  
Sea Level Fluctuations ◽  
The North ◽  
Inundation Area ◽  
Flooded Area

The article presents the results of hydrodynamic modeling of sea level fluctuations in the Caspian Sea using the ADCIRC model for the period from 1979 to 2017. Surges are simulated using an irregular triangulation computational grid with a changing cell size, that easily adapts to changes in shoreline and depth and, therefore, more accurately describes coastal zones. It is found that the seasonal variability of surges is characterized by a maximum in winter and spring and by a minimum in summer. On the western coast of the North Caspian Sea, the maximum sea-level fluctuations are observed in December-February, and on the northern and eastern coasts – in February and March. The areas of inundation of the coastal territory of the Russian sector of the sea are identified. For the surge on March 12–16, 1995, that was one of the most catastrophic ones in terms of its consequences, the inundation area made up 53% of the possible flooded area, and the inundation area for the surge registered on March 27–April 1, 2015 made up 71 %. The more severe consequences of the surge in 1995 are associated with the fact that the mean annual sea level, that determines the possible flooded area, in 1995 was much higher than in 2015. Keywords: ADCIRC, Caspian Sea, unstructured grid, storm surge, sea level, numerical modeling Fig. 11. Ref. 15.

scholarly journals Caspian sea-level changes during the last millennium: historical and geological evidence from the south Caspian Sea

2013 ◽  
Vol 9 (4) ◽  
pp. 1645-1665 ◽  
Author(s):  
A. Naderi Beni ◽  
H. Lahijani ◽  
R. Mousavi Harami ◽  
K. Arpe ◽  
S. A. G. Leroy ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Sediment Cores ◽  
Ice Age ◽  
Last Millennium ◽  
Sea Level Changes ◽  
The South ◽  
Geological Evidence ◽  
Base Level ◽  
Sea Level Oscillations

Abstract. Historical literature may constitute a valuable source of information to reconstruct sea-level changes. Here, historical documents and geological records have been combined to reconstruct Caspian sea-level (CSL) changes during the last millennium. In addition to a comprehensive literature review, new data from two short sediment cores were obtained from the south-eastern Caspian coast to identify coastal change driven by water-level changes and to compare the results with other geological and historical findings. The overall results indicate a high-stand during the Little Ice Age, up to −21 m (and extra rises due to manmade river avulsion), with a −28 m low-stand during the Medieval Climate Anomaly, while presently the CSL stands at −26.5 m. A comparison of the CSL curve with other lake systems and proxy records suggests that the main sea-level oscillations are essentially paced by solar irradiance. Although the major controller of the long-term CSL changes is driven by climatological factors, the seismicity of the basin creates local changes in base level. These local base-level changes should be considered in any CSL reconstruction.

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