scholarly journals Bathymetry and oceanic flow structure at two deep passages crossing the Lomonosov Ridge

2017 ◽  
Author(s):  
Göran Björk ◽  
Martin Jakobsson ◽  
Karen Assmann ◽  
Leif Andersson ◽  
Johan Nilsson ◽  
...  
Keyword(s):  
Water Exchange ◽  
The Arctic ◽  
Morphological Evidence ◽  
Lomonosov Ridge ◽  
Hydrographic Data ◽  
Bathymetric Survey ◽  
Water Properties ◽  
Makarov Basin ◽  
Topographical Feature ◽  
Sill Depth

Abstract. The Lomonosov Ridge represents a major topographical feature in the Arctic Ocean which has a large effect on the water circulation and the distribution of water properties. This study presents detailed bathymetric survey data along with hydrographic data at two deep passages across the ridge: A southern passage (80–81° N) where the ridge crest meets the Siberian continental slope and a northern passage around 84.5° N. The southern channel is characterized by smooth and flat bathymetry around 1600–1700 m with a sill depth slightly shallower than 1700 m. A hydrographic section across the channel reveals an eastward flow with Amundsen Basin properties in the southern part and a westward flow of Makarov Basin properties in the northern part. The northern passage includes an approximately 72 km long and 33 km wide trough which forms an intra basin in the Lomonosov Ridge morphology (the Oden Trough). The eastern side of Oden Trough is enclosed by a narrow and steep ridge rising 500–600 m above a generally 1600 m deep trough bottom. The deepest passage (the sill) is 1470 m deep and located on this ridge. Hydrographic data show irregular temperature and salinity profiles indicating that water exchange occurs as midwater intrusions bringing water properties from each side of the ridge in well-defined but irregular layers. There is also morphological evidence that some rather energetic flows may occur in the vicinity of the sill. A well expressed deepening near the sill may be the result of seabed erosion by bottom currents.

scholarly journals Bathymetry and oceanic flow structure at two deep passages crossing the Lomonosov Ridge

Ocean Science ◽  
2018 ◽  
Vol 14 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Göran Björk ◽  
Martin Jakobsson ◽  
Karen Assmann ◽  
Leif G. Andersson ◽  
Johan Nilsson ◽  
...  
Keyword(s):  
Water Exchange ◽  
The Arctic ◽  
Morphological Evidence ◽  
Lomonosov Ridge ◽  
Hydrographic Data ◽  
Bathymetric Survey ◽  
Water Properties ◽  
Makarov Basin ◽  
Topographical Feature ◽  
Sill Depth

Abstract. The Lomonosov Ridge represents a major topographical feature in the Arctic Ocean which has a large effect on the water circulation and the distribution of water properties. This study presents detailed bathymetric survey data along with hydrographic data at two deep passages across the ridge: a southern passage (80–81∘ N), where the ridge crest meets the Siberian continental slope, and a northern passage around 84.5∘ N. The southern channel is characterized by smooth and flat bathymetry around 1600–1700 m with a sill depth slightly shallower than 1700 m. A hydrographic section across the channel reveals an eastward flow with Amundsen Basin properties in the southern part and a westward flow of Makarov Basin properties in the northern part. The northern passage includes an approximately 72 km long and 33 km wide trough which forms an intra-basin in the Lomonosov Ridge morphology (the Oden Trough). The eastern side of the Oden Trough is enclosed by a narrow and steep ridge rising 500–600 m above a generally 1600 m deep trough bottom. The deepest passage (the sill) is 1470 m deep and located on this ridge. Hydrographic data show irregular temperature and salinity profiles indicating that water exchange occurs as midwater intrusions bringing water properties from each side of the ridge in well-defined but irregular layers. There is also morphological evidence that some rather energetic flows may occur in the vicinity of the sill. A well expressed deepening near the sill may be the result of seabed erosion by bottom currents.

scholarly journals Evolution of the Deep Water in the Canadian Basin in the Arctic Ocean

2006 ◽  
Vol 36 (5) ◽  
pp. 866-874 ◽  
Author(s):  
M-L. Timmermans ◽  
Chris Garrett
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
Bottom Layer ◽  
Canada Basin ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Geothermal Heat ◽  
Makarov Basin ◽  
The Arctic Ocean ◽  
Canadian Basin

Abstract An overflow of magnitude 0.25 Sv (Sv ≡ 106 m−3 s−1) has been predicted to enter the Makarov Basin (part of the Canadian Basin in the Arctic Ocean) from the Eurasian Basin via a deep gap in the dividing Lomonosov ridge. The authors argue that this overflow does not ventilate the deep Makarov Basin (below 2400 m) where the water is too warm and salty to be compatible with such a large cold fresh inflow. However, complete isolation of the homogeneous bottom layer of the Makarov Basin must be ruled out because changes there are too small to arise from more than a small fraction of the measured geothermal heat flux into the basin. A small cold fresh inflow of about 0.01 Sv from the Amundsen Basin seems to be required. This could occur if the gap in the dividing Lomonosov Ridge is shallower than previously thought. It could also occur if there is active mixing and dilution of the predicted overflow in the gap, leaving only a small fraction to descend into the deep Makarov Basin. Hydraulic theory and hydrographic observations are used to rule out any significant flow of dense water from the Makarov Basin into the deep Canada Basin, confirming previous hypotheses of isolation of the deep water in the Canada Basin.

Correlations between the Lomonosov Ridge, Marvin Spur and adjacent basins of the Arctic Ocean based on seismic data

2009 ◽  
Vol 472 (1-4) ◽  
pp. 309-322 ◽  
Author(s):  
A.E. Langinen ◽  
N.N. Lebedeva-Ivanova ◽  
D.G. Gee ◽  
Yu.Ya. Zamansky
Keyword(s):  
Arctic Ocean ◽  
Seismic Data ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
The Arctic Ocean

scholarly journals Changing sources and environmental factors reduce the rates of decline of organochlorine pesticides in the Arctic Atmosphere

2009 ◽  
Vol 9 (1) ◽  
pp. 515-540 ◽  
Author(s):  
S. Becker ◽  
C. J. Halsall ◽  
W. Tych ◽  
R. Kallenborn ◽  
M. Schlabach ◽  
...  
Keyword(s):  
Water Exchange ◽  
Significant Decline ◽  
Primary Sources ◽  
The Arctic ◽  
Secondary Sources ◽  
Increasing Trend ◽  
Cyclical Behaviour ◽  
Harmonic Regression ◽  
Arctic Atmosphere ◽  
Isomeric Ratios

Abstract. An extensive database of organochlorine (OC) pesticide concentrations measured at the Norwegian Arctic Monitoring Station was analysed to assess longer-term trends in the Arctic atmosphere. Dynamic Harmonic Regression (DHR) is employed to investigate the seasonal and cyclical behaviour of chlordanes, DDTs and hexachlorobenzene (HCB), and to isolate underlying inter-annual trends. Although a simple comparison of annual mean concentrations (1994–2005) suggest a decline for all of the OCs investigated, the longer-term trends identified by DHR only show a significant decline for p,p'-DDT. Indeed, HCB shows an increase from 2003–2005. This is thought to be due to changes in source types and the presence of impurities in current use pesticides, together with retreating sea ice affecting air-water exchange. Changes in source types were revealed by using isomeric ratios for the chlordanes and DDTs. Declining trends in ratios of trans-chlordane/cis-chlordane (TC/CC) indicate a shift from primary sources, to more ''weathered'' secondary sources, whereas an increasing trend in o,p'-DDT/p,p'-DDT ratios indicate a shift from use of technical DDT to dicofol. Continued monitoring of these OC pesticides is required to fully understand the influence of a changing climate on the behaviour and environmental cycling of these chemicals in the Arctic as well as possible impacts from ''new'' sources.

scholarly journals Mass wasting at the Siberian termination of Lomonosov Ridge, Arctic Ocean

2020 ◽  
Author(s):  
Ursula Schlager ◽  
Wilfried Jokat ◽  
Estella Weigelt
Keyword(s):  
Arctic Ocean ◽  
Ice Sheets ◽  
Seismic Stratigraphy ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Mass Wasting ◽  
Swath Bathymetry ◽  
Seismic Amplitudes ◽  
Drill Holes ◽  
Mass Volume

<p>The Lomonosov Ridge is an 1800 km long continental sliver in the center of the Arctic Ocean. Beside its tectonic relevance it hosts glaciogenic features caused either by deep reaching icebergs or grounded ice sheets as well as indications for mass wastings. Systematic swath bathymetry acquired in 2014 provided an almost complete image of these shallow disturbances from almost 84˚ N to the foot of the Laptev margin.</p><p>Several arcuate transverse features are present on both sides of the crest of the eastern part of Lomonosov Ridge between 81˚ and 84˚ N. Eight of them are 2.1-10.2 km wide, 1.7-8.2 km long, 125-851 m deep, with height of headwall between 58-207 m and a slid mass volume of 0.09-7.58 km<sup>3</sup>. Due to the absence of scientific drill holes only a tentative seismic stratigraphy can be used for a rough age estimate of the mass wasting. All but one show a glide plane on top of a pronounced stratigraphic seismic horizon with strong seismic amplitudes. We will introduce the different geometries and statistics of these mass wasting features.</p>

scholarly journals Early to middle Eocene history of the Arctic Ocean from Nd-Sr isotopes in fossil fish debris, Lomonosov Ridge

2009 ◽  
Vol 24 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. D. Gleason ◽  
D. J. Thomas ◽  
T. C. Moore ◽  
J. D. Blum ◽  
R. M. Owen ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Middle Eocene ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Sr Isotopes ◽  
Fossil Fish ◽  
The Arctic Ocean ◽  
History Of

scholarly journals Changing sources and environmental factors reduce the rates of decline of organochlorine pesticides in the Arctic atmosphere

2012 ◽  
Vol 12 (9) ◽  
pp. 4033-4044 ◽  
Author(s):  
S. Becker ◽  
C. J. Halsall ◽  
W. Tych ◽  
R. Kallenborn ◽  
M. Schlabach ◽  
...  
Keyword(s):  
Water Exchange ◽  
Significant Decline ◽  
Primary Sources ◽  
The Arctic ◽  
Secondary Sources ◽  
Increasing Trend ◽  
Cyclical Behaviour ◽  
Harmonic Regression ◽  
Arctic Atmosphere ◽  
Isomeric Ratios

Abstract. An extensive database of organochlorine (OC) pesticide concentrations measured at the Norwegian Arctic monitoring station at Ny-Ålesund, Svalbard, was analysed to assess longer-term trends in the Arctic atmosphere. Dynamic Harmonic Regression (DHR) is employed to investigate the seasonal and cyclical behaviour of chlordanes, DDTs and hexachlorobenzene (HCB), and to isolate underlying inter-annual trends. Although a simple comparison of annual mean concentrations (1994–2005) suggest a decline for all of the OCs investigated, the longer-term trends identified by DHR only show a significant decline for p,p'-DDT. Indeed, HCB shows an increase from 2003–2005. This is thought to be due to changes in source types and the presence of impurities in current use pesticides, together with retreating sea ice affecting air-water exchange. Changes in source types were revealed by using isomeric ratios for the chlordanes and DDTs. Declining trends in ratios of trans-chlordane/cis-chlordane (TC/CC) indicate a shift from primary sources, to more "weathered" secondary sources, whereas an increasing trend in o,p'-DDT/p,p'-DDT ratios indicate a shift from use of technical DDT to dicofol. Continued monitoring of these OC pesticides is required to fully understand the influence of a changing climate on the behaviour and environmental cycling of these chemicals in the Arctic as well as possible impacts from "new" sources.

scholarly journals Natural variability of the Arctic Ocean sea ice during the present interglacial

2020 ◽  
Vol 117 (42) ◽  
pp. 26069-26075
Author(s):  
Anne de Vernal ◽  
Claude Hillaire-Marcel ◽  
Cynthia Le Duc ◽  
Philippe Roberge ◽  
Camille Brice ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Natural Variability ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Arctic Sea ◽  
The Arctic Ocean ◽  
Open Question ◽  
The Impact

The impact of the ongoing anthropogenic warming on the Arctic Ocean sea ice is ascertained and closely monitored. However, its long-term fate remains an open question as its natural variability on centennial to millennial timescales is not well documented. Here, we use marine sedimentary records to reconstruct Arctic sea-ice fluctuations. Cores collected along the Lomonosov Ridge that extends across the Arctic Ocean from northern Greenland to the Laptev Sea were radiocarbon dated and analyzed for their micropaleontological and palynological contents, both bearing information on the past sea-ice cover. Results demonstrate that multiyear pack ice remained a robust feature of the western and central Lomonosov Ridge and that perennial sea ice remained present throughout the present interglacial, even during the climate optimum of the middle Holocene that globally peaked ∼6,500 y ago. In contradistinction, the southeastern Lomonosov Ridge area experienced seasonally sea-ice-free conditions, at least, sporadically, until about 4,000 y ago. They were marked by relatively high phytoplanktonic productivity and organic carbon fluxes at the seafloor resulting in low biogenic carbonate preservation. These results point to contrasted west–east surface ocean conditions in the Arctic Ocean, not unlike those of the Arctic dipole linked to the recent loss of Arctic sea ice. Hence, our data suggest that seasonally ice-free conditions in the southeastern Arctic Ocean with a dominant Arctic dipolar pattern, may be a recurrent feature under “warm world” climate.

scholarly journals Empirical Relationships between Remote-Sensing Reflectance and Selected Inherent Optical Properties in Nordic Sea Surface Waters for the MODIS and OLCI Ocean Colour Sensors

2020 ◽  
Vol 12 (17) ◽  
pp. 2774
Author(s):  
Marta Konik ◽  
Piotr Kowalczuk ◽  
Monika Zabłocka ◽  
Anna Makarewicz ◽  
Justyna Meler ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Large Scale ◽  
Field Work ◽  
The Arctic ◽  
Significant Shift ◽  
Form Complex ◽  
Water Properties ◽  
Remote Sensing Reflectance ◽  
Phytoplankton Communities

The Nordic Seas and the Fram Strait regions are a melting pot of a number of water masses characterized by distinct optical water properties. The warm Atlantic Waters transported from the south and the Arctic Waters from the north, combined with the melt waters contributing to the Polar Waters, mediate the dynamic changes of the year-to-year large-scale circulation patterns in the area, which often form complex frontal zones. In the last decade, moreover, a significant shift in phytoplankton phenology in the area has been observed, with a certain northward expansion of temperate phytoplankton communities into the Arctic Ocean which could lead to a deterioration in the performance of remote sensing algorithms. In this research, we exploited the capability of the satellite sensors to monitor those inter-annual changes at basin scales. We propose locally adjusted algorithms for retrieving chlorophyll a concentrations Chla, absorption by particles ap at 443 and 670 nm, and total absorption atot at 443 and 670 nm developed on the basis of intensive field work conducted in 2013–2015. Measured in situ hyper spectral remote sensing reflectance has been used to reconstruct the MODIS and OLCI spectral channels for which the proposed algorithms have been adapted. We obtained MNB ≤ 0.5% for ap(670) and ≤3% for atot(670) and Chla. RMS was ≤30% for most of the retrieved optical water properties except ap(443) and Chla. The mean monthly mosaics of ap(443) computed on the basis of the proposed algorithm were used for reconstructing the spatial and temporal changes of the phytoplankton biomass in 2013–2015. The results corresponded very well with in situ measurements.

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