Kinematic Model of Development of Eastern Areas of the Gakkel Mid-Ocean Ridge in the Eurasian Basin of the Arctic Ocean

Oceanology ◽  
2019 ◽  
Vol 59 (1) ◽  
pp. 133-142
Author(s):  
Al. A. Schreider ◽  
A. A. Schreider ◽  
A. E. Sazhneva ◽  
M. S. Kluev ◽  
A. L. Brehovskih
2018 ◽  
Vol 32 (1) ◽  
pp. 15-32 ◽  
Author(s):  
Qiang Wang ◽  
Claudia Wekerle ◽  
Sergey Danilov ◽  
Dmitry Sidorenko ◽  
Nikolay Koldunov ◽  
...  

Abstract The freshwater stored in the Arctic Ocean is an important component of the global climate system. Currently the Arctic liquid freshwater content (FWC) has reached a record high since the beginning of the last century. In this study we use numerical simulations to investigate the impact of sea ice decline on the Arctic liquid FWC and its spatial distribution. The global unstructured-mesh ocean general circulation model Finite Element Sea Ice–Ocean Model (FESOM) with 4.5-km horizontal resolution in the Arctic region is applied. The simulations show that sea ice decline increases the FWC by freshening the ocean through sea ice meltwater and modifies upper ocean circulation at the same time. The two effects together significantly increase the freshwater stored in the Amerasian basin and reduce its amount in the Eurasian basin. The salinification of the upper Eurasian basin is mainly caused by the reduction in the proportion of Pacific Water and the increase in that of Atlantic Water (AW). Consequently, the sea ice decline did not significantly contribute to the observed rapid increase in the Arctic total liquid FWC. However, the changes in the Arctic freshwater spatial distribution indicate that the influence of sea ice decline on the ocean environment is remarkable. Sea ice decline increases the amount of Barents Sea branch AW in the upper Arctic Ocean, thus reducing its supply to the deeper Arctic layers. This study suggests that all the dynamical processes sensitive to sea ice decline should be taken into account when understanding and predicting Arctic changes.


2015 ◽  
Vol 132 ◽  
pp. 128-152 ◽  
Author(s):  
Bert Rudels ◽  
Meri Korhonen ◽  
Ursula Schauer ◽  
Sergey Pisarev ◽  
Benjamin Rabe ◽  
...  

1999 ◽  
Vol 21 (1-4) ◽  
pp. 3-27 ◽  
Author(s):  
Bert Rudels ◽  
Göran Björk ◽  
Robin D Muench ◽  
Ursula Schauer

2019 ◽  
Author(s):  
Nataliya Zhurbas ◽  
Natalia Kuzmina

Abstract. Data of CTD transects across continental slope of the Eurasian Basin and the St. Anna Trough performed during NABOS (Nansen and Amundsen Basins Observing System) project in 2003–2015 are used to assess transport and propagation features of the Atlantic Water (AW) in the Arctic Ocean. Estimates of θ-S indices and volume flow rate of the current carrying the AW in the Eurasian Basin were obtained. The assessments were based on the analysis of CTD data including 33 sections in the Eurasian Basin, 4 transects in the St. Anna Trough and 2 transects in the Makarov Basin; additionally a CTD transect of the PolarStern-1996 expedition (PS-96) was considered. Using spatial distributions of temperature, salinity, and density on the transects and applying θ-S analysis, the variability of thermohaline pattern on the AW pathway along the slope of Eurasian Basin was investigated. The Fram Strait branch of the Atlantic Water (FSBW) was satisfactorily identified on all transects, including two transects in the Makarov Basin (along 159° E), while the сold waters, which can be associated with the influence of the Barents Sea branch of the Atlantic water (BSBW), on the transects along 126° E, 142° E and 159° E, were observed in the depth range below 800 m and had a negligible effect on the spatial structure of isopycnic surfaces. Special attention was paid to the variability of the volume flow rate of the AW propagating along the continental slope of the Eurasian Basin. The geostrophic volume flow rate was calculated using the dynamic method. An interpretation of the spatial and temporal variability of hydrological parameters characterizing the flow of the AW in the Eurasian Basin is presented. The geostrophic volume flow rate decreases significantly farther away from the areas of the AW inflow to the Eurasian Basin. Thus, the geostrophic estimate of the volume rate for the AW flow in the Makarov Basin at 159° E was found to be more than an order of magnitude smaller than the estimates of the volume flow rate in the Eurasian Basin, implying that the major part of the AW entering the Arctic Ocean circulates cyclonically within the Nansen and Amundsen Basins. There is an absolute maximum of θmax (AW core temperature) in 2006–2008 time series and a maximum in 2013, but only at 103° E. Salinity S(θmax) (AW core salinity) time series display an increase of the AW salinity in 2006–2008 and 2013 (at 103° E) that can be referred to as a AW salinization in the early 2000-ies. The maxima of θmax and S(θmax) in 2006–2008 and 2013 were accompanied by the volume flow rate highs. Additionally the time average volume rates were calculated for the FSBW flow (in the longitude range 31–92° E), for the BSBW flow in the St. Anna Trough and for a combined FSBW and BSBW flow in longitude range 94–107° E. A detailed discussion of the results is presented.


2021 ◽  
Author(s):  
Marina Tarkhanova ◽  
Elena Golubeva

<p>The report discusses issues related to the influence of the increased discharge of Arctic rivers on the thermohaline structure of waters outside the Arctic shelf and, in particular, on the variability of Arctic Ocean heat content. The three-dimensional numerical model of the ocean and sea ice SibCIOM (Siberian Coupled Ice-Ocean Model), developed at the Institute of Computational Mathematics and Mathematical Geophysics SB RAS to study the climatic variability of the Arctic Ocean, and the NCEP/NCAR atmospheric reanalysis data are used.</p><p>To reveal the sensitivity of the model fields to the intensity of river runoff, numerical experiments assume the inclusion of variations in river discharge with unchanged remaining conditions, starting from 2000. The deviations of the monthly average values in a numerical experiment with increased discharge of individual Arctic rivers from the basic situation based on the monthly average climatic runoff assignment are considered.</p><p>An analysis of the numerical results obtained with increased discharge of the major Siberian rivers (Ob, Yenisei, Lena) by 1.3 times showed an increase in the Kara Sea's bottom temperature. This was followed by the warming of the subsurface layer of the waters propagating along the continental slope and increasing the heat content of the upper 200-meter layer of the Eastern Eurasian Basin. The heat preservation entering the deep-water part through the Kara Sea straits was facilitated by an increase in stratification's stability and a decrease of the mixed layer depth by 5-10 m on the continental slope of the Eurasian Basin. A similar process with a time delay (6-7 years) and on a smaller scale is developing on the Amerasian basin's continental slope and the Chukchi Sea shelf.</p><p>In the numerical experiment with an increased discharge of the Mackenzie River, deviations in the Beaufort Sea heat and freshwater content appear during the first two years. Still, their values are too small under the river's small discharge compared to the Siberian rivers' discharge.</p><p>The study is supported by the Russian Foundation for Basic Research, Grant No. 20-05-00536 A.</p>


2018 ◽  
Author(s):  
Andrey Pnyushkov ◽  
Igor Polyakov ◽  
Robert Rember ◽  
Vladimir Ivanov ◽  
Matthew B. Alkire ◽  
...  

Abstract. This study discusses along-slope volume, heat, and salt transports derived from observations collected in 2013–15 using a cross-slope array of six moorings ranging from 250 m to 3900 m in the eastern Eurasian Basin (EB) of the Arctic Ocean. These observations demonstrate that in the upper 780 m layer, the along-slope boundary current advected, on average, 5.1 ± 0.1 Sv of water, predominantly in the eastward (shallow-to-right) direction. Monthly net volume transports across the Laptev Sea slope vary widely, from ~ 0.3 ± 0.8 in April 2014 to ~ 9.9 ± 0.8 Sv in June 2014. 3.1 ± 0.1 Sv (or 60 %) of the net transport was associated with warm and salty intermediate-depth Atlantic Water (AW). Calculated heat transport for 2013–15 (relative to −1.8 °C) was 46.0 ± 1.7 TW, and net salt transport (relative to zero salinity) was 172 ± 6 Mkg/s. Estimates for AW heat and salt transports were 32.7 ± 1.3 TW (71 % of net heat transport) and 112 ± 4 Mkg/s (65 % of net salt transport). The variability of currents explains ~ 90 % of the variability of the heat and salt transports. The remaining ~ 10 % is controlled by temperature and salinity anomalies together with temporal variability of the AW layer thickness. The annual mean volume transports decreased by 25 % from 5.8 ± 0.2 Sv in 2013–14 to 4.4 ± 0.2 Sv in 2014–15 suggesting that changes of the transports at interannual and longer time scales in the eastern EB may be significant.


2019 ◽  
Vol 59 (1) ◽  
pp. 143-152
Author(s):  
Al. A. Schreider ◽  
A. A. Schreider ◽  
A. E. Sazhneva ◽  
M. S. Kluev ◽  
A. L. Brehovskih

The new map of linear magnetic anomalies axis for the mid-Arctic ridge east areas development in the Eurasian basin is made. The domestic geomagnetic investigations for the first time allow to determine paleomagnetic anomaly C25 and estimate the time of transfer rifting to spreading process as chrons С25r-С26n (57.656-59.237 ma). The eastablishing of Lomonosov ridge and Siberian margin splitting zone is made. The Euler pole for the splitting kinematic for first time calculated. The nocoinciding of conjugate isobaths related to process of sliding peripheral continental crust areas along lithosphere thrust plane for the first time is calculate.


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