scholarly journals Modelling seasonal circulation and thermohaline structure of the Caspian Sea

Ocean Science ◽  
2014 ◽  
Vol 10 (3) ◽  
pp. 459-471 ◽  
Author(s):  
M. Gunduz ◽  
E. Özsoy
Keyword(s):  
Caspian Sea ◽  
Cyclonic Circulation ◽  
Sea Surface ◽  
Eastern Coast ◽  
The Caspian Sea ◽  
Mesoscale Dynamics ◽  
Mesoscale Structures ◽  
Seasonal Circulation ◽  
Current Systems ◽  
Mixing And Transport

Abstract. The wind- and buoyancy-driven seasonal circulation of the Caspian Sea is investigated for a better understanding of its basin-wide and mesoscale dynamics, mixing and transport. The model successfully reproduces the following basic elements of the circulation: the southward-flowing current systems along the eastern and western coasts, the upwelling along the eastern coast, the cyclonic circulation in the Middle Caspian Sea (MCS), especially in winter, and the cyclonic and anticyclonic cells of circulation in the South Caspian Sea (SCS). The observed seasonal variability of sea level and sea surface temperature (SST) is well reproduced. Mesoscale structures, not always evident from hydrographic observations, are identified.

scholarly journals Modelling Seasonal Circulation and Thermohaline Structure of the Caspian Sea

2014 ◽  
Vol 11 (1) ◽  
pp. 259-292 ◽  
Author(s):  
M. Gunduz ◽  
E. Özsoy
Keyword(s):  
Caspian Sea ◽  
Cyclonic Circulation ◽  
Sea Surface ◽  
Eastern Coast ◽  
The Caspian Sea ◽  
Mesoscale Structures ◽  
Seasonal Circulation ◽  
Current Systems ◽  
Meso Scale ◽  
Mixing And Transport

Abstract. The wind and buoyancy driven seasonal circulation of the Caspian Sea is investigated for a better understanding of its basin-wide and meso-scale dynamics, mixing and transport. The model successfully reproduces the following basic elements of the circulation: the southward flowing current systems along the eastern and western coasts, the upwelling along the eastern coast, the cyclonic circulation in the Middle Caspian Sea (MCS) especially in winter, and the cyclonic and anticyclonic cells of circulation in the South Caspian Sea (SCS). The observed seasonal variability of sea level and sea surface temperature (SST) is well reproduced. Mesoscale structures, not always evident from hydrographic observations, are identified.

On the type locality of the steppe ribbon racer, Psammophis lineolatus (Brandt, 1838) (Serpentes: Lamprophiidae)

2020 ◽  
Vol 324 (2) ◽  
pp. 262-272
Author(s):  
I.V. Doronin ◽  
T.N. Dujsebayeva ◽  
K.M. Akhmedenov ◽  
A.G. Bakiev ◽  
K.N. Plakhov
Keyword(s):  
Caspian Sea ◽  
Type Specimen ◽  
Type Locality ◽  
Eastern Coast ◽  
Zoological Museum ◽  
Western Coast ◽  
The Caspian Sea ◽  
Original Species ◽  
Academy Of Sciences ◽  
Made In

The article specifies the type locality of the Steppe Ribbon Racer. The holotype Coluber (Taphrometopon) lineolatus Brandt, 1838 is stored in the reptile collection of the Zoological Institute of the Russian Academy of Sciences (ZISP No 2042). Literature sources provide different information about the type locality. A mistake has been made in the title of the work with the original species description: the western coast of the sea was indicated instead of the eastern one. The place of capture was indicated as “M. Caspium” (Caspian Sea) on the label and in the reptile inventory book of the Zoological Museum of the Academy of Sciences. The specimen was sent to the museum by G.S. Karelin. The “1842” indicated on the labels and in the inventory book cannot be the year of capture of the type specimen, just as the “1837” indicated by A.M. Nikolsky. In 1837, Karelin was in Saint Petersburg and in 1842 in Siberia. Most likely, 1837 is the year when the collection arrived at the Museum, and 1842 is the year when the information about the specimen was recorded in the inventory book (catalog) of the Zoological Museum of the Academy of Sciences. In our opinion, the holotype was caught in 1932. From Karelin’s travel notes of the expedition to the Caspian Sea in 1832, follows that the snake was recorded in two regions adjacent to the eastern coast of the Caspian Sea – Ungoza Mountain (“Mangyshlak Mountains”) and site of the Western Chink of Ustyurt between Zhamanairakty and Kyzyltas Mountains (inclusive) on the northeast coast of Kaydak Sor (“Misty Mountains”). In our article, Karelin’s route to the northeastern coast of the Caspian Sea in 1832 and photographs of these localities are given. The type locality of Psammophis lineolatus (Brandt, 1838) should be restricted to the Mangystau Region of the Kazakhstan: Ungoza Mountain south of Sarytash Gulf, Mangystau (Mangyshlak) Penninsula (44°26´ N, 51°12´ E).

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.

FEATURES OF SNOW COVER OF SEMI-DESERTS AND DRY STEPPES OF THE CASPIAN SEA ACCORDING TO SATELLITE DATA FOR THE PERIOD 2001...2020

2021 ◽  
Vol 101 (2) ◽  
pp. 80-87
Author(s):  
A.G Terekhov ◽  
◽  
N.I. Ivkina ◽  
N.N. Abayev ◽  
A.V. Galayeva ◽  
...  
Keyword(s):  
Snow Cover ◽  
Caspian Sea ◽  
Snow Depth ◽  
Eastern Coast ◽  
The Caspian Sea ◽  
Dry Steppe ◽  
Natural Tendency ◽  
Second Mode ◽  
Continental Climate

The Snow Depth FEWS NET daily product was used to analyze snowy regime of the upper part of the River Emba basin from January 1 to April 30 for the period of 2001...2020. The Emba River basin is situated in Kazakhstan at the Eastern coast of the Caspian Sea. The area is characterized by the arid and extreme continental climate with dry-steppe and semi-desert landscapes. The population is small and the anthropogenic impact on the snow cover is minimal there. These conditions give an opportunity to identify the natural tendency in long-term changes of snow covering in semidesert zone of Kazakhstan. This paper describes the characteristics of the formation and destruction of the snow cover in the last 20 years. It was indicated that snowy regime has a trigger structure including two states; low-snowy regime and others years. It was shown that the snowy conditions are triggered. There are two modes, the first, as a low-snowy regime (up to 50 % of the entire sample) and the second mode includes other years. Significant variations of snow depth in various years masked many years’ tendencies of snow cover characteristics. But low-snowy regime was observed four times during five last years that can relate with modern decreasing snow covering in semi-desert zone of Kazakhstan.

Spatio-temporal variability of internal waves in the Caspian Sea

2020 ◽  
Author(s):  
Olga Lavrova ◽  
Andrey Kostianoy
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Internal Waves ◽  
Satellite Data ◽  
Caspian Sea ◽  
Bottom Topography ◽  
Sea Surface ◽  
Anthropogenic Factors ◽  
Landsat 8 ◽  
The Caspian Sea

<p>Internal waves (IWs) are an intrinsic feature of all density stratified water bodies: oceans, seas, lakes and reservoirs. IWs occur due to various causes. Among them are tides and inertial motions, variations in atmospheric pressure and wind, underwater earthquakes, water flows over bottom topography, anthropogenic factors, etc. In coastal areas of oceans and tidal seas,  IWs induced by tidal currents over shelf edge predominate. Such IWs are well-studied in multiple field, laboratory and numerical experiments. However, the data on IWs in non-tidal seas, such as the Black, Baltic and Caspian Seas, are scarce. Meanwhile, our multi-year satellite observations prove IWs to be quite a characteristic hydrophysical phenomenon of the Caspian Sea. The sea is considered non-tidal because tide height does not exceed 12 cm at the coastline. And yet surface manifestations of IWs are regularly observed in satellite data, both radar and visible. The goal of our study was to reveal spatial, seasonal and interannual variability of IW surface manifestations in the Caspian Sea in the periods of 1999-2012 and 2018-2019 from the analysis of satellite data. All available satellite radar and visible data were used, that is data from ERS1/2 SAR; Envisat ASAR; Sentinel-1A,1B SAR-C; Landsat-4,5 TM; Landsat-7 ETM+; Landsat-8 OLI; Sentinel-2A,2B MSI sensors. During the year, IWs were observed from the beginning of May to mid-September. In certain years, depending on hydrometeorological conditions, such as water heating, wind field, etc., no IWs could be seen in May or September. IWs regularly occur in the east of Middle Caspian and in the northeast of South Caspian. In North Caspian, due to its shallowness and absence of pronounced stratification, IWs are not generated, at least their surface signatures cannot be found in satellite data. In the west of the sea, IWs are scarcely observed, primarily at the beginning of the summer season. IW trains propagate toward the coast, their generation sites are mainly over the depths of 50-200 m.</p><p>According to the available data for the studied periods, the time of the first appearance of IW signatures differs significantly from year to year. For example, in 1999 and 2000 it happened only in July.</p><p>Since no in situ measurements were conducted in the sites of regular IW manifestations, an attempt  was made to establish the dependence of IW occurrence frequency  on seasonal and interannual variations of sea surface temperature, an indirect indicator of the depth of the diurnal or seasonal thermocline, that is where IW were generated. Sea surface temperature was also estimated from satellite data.</p><p>Another issue addressed in the work was the differentiation between the sea surface signatures of IWs in the atmosphere and the sea. The Caspian Sea is known for their close similarity in spatial characteristics.</p><p>The work was carried out with financial support of the Russian Science Foundation grant #19-77-20060.  Processing of satellite data was carried out by Center for Collective Use “IKI-Monitoring” with the use of “See The Sea” system, that was implemented in frame of Theme “Monitoring”, State register No. 01.20.0.2.00164.</p>

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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