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  • 1
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    The penetrative mixing in the Laptev Sea coastal polynya pycnocline layer (2013)
    Elsevier
    In:  Continental Shelf Research, 63 . pp. 34-42.
    Details
    Publication Date: 2019-09-23
    Description: The large recurrent areas of open water and/or thin ice (polynyas) producing cold brine-enriched waters off the fast-ice edge are evident in the Laptev Sea in winter time. A number of abrupt positively correlated transitions in temperature and salinity were recorded in the bottom and intermediate layers at a mooring station in the West New Siberian (WNS) polynya in February-March 2008. Being in the range of -0.5 degrees C and -1.6 psu these changes are induced by horizontal motions across the polynya and correspond to temperature and salinity horizontal gradients in the range of 0.3-1.0 degrees C/10 km and 1.4-3.5 psu/10 km, respectively. The events of distinct freshening and temperature decrease coincide with a northward current off the fast-ice edge, while southward currents brought saltier and warmer waters at intermediate depths. We suggest that the observed transitions are connected to altering pycnocline depths across the polynya. The source of relatively fresher waters at the intermediate depths in polynya is supposed to originate from penetrative mixing of surface low salinity waters to intermediate water depth. Several forcing processes that could be responsible for a penetrative mixing through the density interface in polynya are discussed. These are penetrative convection and shear-driven mixing that originates from two-layer water dynamics and/or baroclinic tidal motions. The heavily ridged seaward fast-ice edge could produce an additional source of turbulent mixing even through a shear-free density interface due to the increased roughness at the ice-water interface
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.csr.2013.04.040
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Wind-driven diversion of summer river runoff preconditions the Laptev Sea coastal polynya hydrography: Evidence from summer-to-winter hydrographic records of 2007–2009 (2010)
    Elsevier
    In:  Continental Shelf Research, 30 (15). pp. 1656-1664.
    Details
    Publication Date: 2019-09-23
    Description: This paper examines the role of atmospheric forcing in modifying the pathways of riverine water on the Laptev Sea shelf, using summer-to-winter hydrographic surveys from 2007 to 2009. Over the two consecutive winter seasons of 2007–2008 and 2008–2009 in the area of the winter coastal polynya, our data clearly link winter surface salinity fields to the previous summer conditions, with substantially different winter salinity patterns preconditioned by summer atmospheric forcing. In the summer of 2007, dominant along-shore westerly winds in the cyclonic regime force the Lena River runoff to flow eastward. In contrast, in the summer of 2008, dominant along-shore easterly winds over the East Siberian Sea and on-shore northerly winds over the Laptev Sea in the anticyclonic regime lock the riverine water in the vicinity of the Lena Delta. Over the coastal polynya area in the southeastern Laptev Sea these patterns precondition a surface salinity difference of 8–16 psu between the winters of 2008 and 2009. Overall, this indicates a residence time of at least half a year for riverine water on the Laptev Sea shelf. Future climate change associated with an enhanced summer cyclonicity over the eastern Arctic may turn more riverine water eastward along the eastern Siberian coast, resulting in weaker vertical density stratification over the Laptev Sea shelf, with possible impact on the efficiency of vertical mixing and polynya dense water production.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.csr.2010.06.012
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Thermohaline intrusions in the northern Laptev Sea (in Russian) (2008)
    Arkticheskiy i Antarkticheskiy Nauchno-Issledovatel'skiy Institut (Arctic and Antarctic Research Institute)
    In:  In: Raspresnennye vody i presnyy rezerv Severnogo Ledovitogo okeana (Freshened waters and freshwater reserve of the Arctic Ocean, in Russian). Trudy AANII (Proceedings of AARI), 448 . Arkticheskiy i Antarkticheskiy Nauchno-Issledovatel'skiy Institut (Arctic and Antarctic Research Institute), St. Peterburg, Rossiya, pp. 205-216.
    Details
    Publication Date: 2015-04-22
    Type: Book chapter , PeerReviewed
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    OceanRep: Book chapter
  • 4
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    Barents Sea upstream events impact the properties of Atlantic water inflow into the Arctic Ocean: evidence from 2005-2006 downstream observations (2009)
    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 56 (4). pp. 513-527.
    Details
    Publication Date: 2019-12-31
    Description: Inflow of Atlantic water (AW) from Fram Strait and the Barents Sea into the Arctic Ocean conditions the intermediate (100–1000 m) waters of the Arctic Ocean Eurasian margins. While over the Siberian margin the Fram Strait AW branch (FSBW) has exhibited continuous dramatic warming beginning in 2004, the tendency of the Barents Sea AW branch (BSBW) has remained poorly known. Here we document the contrary cooling tendency of the BSBW through the analysis of observational data collected from the icebreaker Kapitan Dranitsyn over the continental slope of the Eurasian Basin in 2005 and 2006. The CTD data from the R.V. Polarstern cruise in 1995 were used as a reference point for evaluating external atmospheric and sea-ice forcing and oxygen isotope analysis. Our data show that in 2006 the BSBW core was saltier (by ∼0.037), cooler (by ∼0.41 °C), denser (by ∼0.04 kg/m3), deeper (by 150–200 m), and relatively better ventilated (by 7–8 μmol/kg of dissolved oxygen, or by 1.1–1.7% of saturation) compared with 2005. We hypothesize that the shift of the meridional wind from off-shore to on-shore direction during the BSBW translation through the Barents and northern Kara seas results in longer surface residence time for the BSBW sampled in 2006 compared with samples from 2005. The cooler, more saline, and better-ventilated BSBW sampled in 2006 may result from longer upstream translation through the Barents and northern Kara seas where the BSBW was modified by sea-ice formation and interaction with atmosphere. The data for stable oxygen isotopes from 1995 and 2006 reveals amplified brine modification of the BSBW core sampled downstream in 2006, which supports the assumption of an increased upstream residence time as indicated by wind patterns and dissolved oxygen values.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.dsr.2008.11.005
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Eurasian Arctic shelf hydrography: exchange and residence time of southern Laptev Sea waters (2009)
    Elsevier
    In:  Continental Shelf Research, 29 (15). pp. 1815-1820.
    Details
    Publication Date: 2019-12-31
    Description: The hydrography of the Laptev Sea is significantly influenced by river water and sea-ice processes, which are highly variable over the annual cycle. Despite of an estuarine structure the inner and outer shelf regions are decoupled at times as documented by the stability of a warm intermediate layer formed during summer below the Lena River plume. We demonstrate that a remnant of this warm layer is preserved below the fast ice until the end of winter, while only slightly farther to the north, offshore of the land fast ice in the polynya region, the pycnocline is eroded and no signature of this layer is found. The warm intermediate layer (WIL) formed during summer can be used as tracer for Laptev Sea shelf waters throughout the winter. There by, residence times of southern Laptev Sea waters can be estimated to be at least from summer to the end of winter/spring of the following year. (C) 2009 Elsevier Ltd. All rights reserved.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1016/j.csr.2009.06.009
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Seasonal variability in Atlantic water off Spitsbergen (2009)
    Elsevier
    In:  Deep Sea Research Part I: Oceanographic Research Papers, 56 (1). pp. 1-14.
    Details
    Publication Date: 2016-11-01
    Description: A combination of 2-year-long mooring-based measurements and snapshot conductivity–temperature–depth (CTD) observations at the continental slope off Spitsbergen (81°30′N, 31°00′E) is used to demonstrate a significant hydrographic seasonal signal in Atlantic Water (AW) that propagates along the Eurasian continental slope in the Arctic Ocean. At the mooring position this seasonal signal dominates, contributing up to 50% of the total variance. Annual temperature maximum in the upper ocean (above 215 m) is reached in mid-November, when the ocean in the area is normally covered by ice. Distinct division into ‘summer’ (warmer and saltier) and ‘winter’ (colder and fresher) AW types is revealed there. Estimated temperature difference between the ‘summer’ and ‘winter’ waters is 1.2 °C, which implies that the range of seasonal heat content variations is of the same order of magnitude as the mean local AW heat content, suggesting an important role of seasonal changes in the intensity of the upward heat flux from AW. Although the current meter observations are only 1-year long, they hint at a persistent, highly barotropic current with little or no seasonal signal attached.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.dsr.2008.07.013
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Suspended particulate matter on the Laptev Sea shelf (Siberian Arctic) during ice-free conditions (2003)
    Elsevier
    In:  Estuarine, Coastal and Shelf Science, 57 (1-2). pp. 55-64.
    Details
    Publication Date: 2019-09-23
    Description: Optical turbidity surveys combined with pigment, plankton, and current measurements were used to investigate the vertical and horizontal dynamics of suspended particulate matter (SPM) in the Laptev Sea, one of the largest Siberian shelf seas, during the ice-free period. Optical measuring devices prove to be an excellent tool to measure SPM distribution in real time. SPM concentrations were quantified owing to the high correlation of water samples and optical backscatter. Thus, the formation and distribution of the bottom nepheloid layer, a layer of increased SPM concentration, and its significance for the sediment transport on the Laptev Sea shelf can be described. Two nepheloid layers exist in the eastern and central Laptev Sea. Formation and concentration of the surface layer are mainly related to the amount of phytoplankton and zooplankton occurrence. However, in the vicinity of the Lena Delta, the concentration is strongly dependent on riverine discharge. The bottom nepheloid layer is suggested to develop during and briefly after the spring breakup, when about 60% of the mean annual sediment input is discharged onto the shelf. SPM spreads over the shelf and is kept in suspension within the bottom layer. Especially during the ice-free period, almost no sedimentation takes place. However, bottom material is resuspended due to wind-induced increased bottom currents, mainly in paleo-river valleys and on shoals. Valleys act as transport conduits during the ice-free period and SPM is shifted within them. An intermediate layer near Stolbovoy Bank is probably caused by the displacement of the bottom layer from the topographic highs into the valleys. The combined turbidity and current measurements indicate that most of the sediment transport on the Laptev Sea shelf takes place in the bottom nepheloid layer.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/S0272-7714(02)00328-1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    Impact of flaw polynyas on the hydrography of the Laptev Sea (2005)
    Elsevier
    In:  Global and Planetary Change, 48 (1-3). pp. 9-27.
    Details
    Publication Date: 2019-09-23
    Description: Based on hydrological data from 1979 to 1999 the average long-term salinity of the flaw polynya in the Eastern Laptev Sea is estimated. A new method to evaluate ice production based on hydrological rather than sea-ice observations is proposed. Average annual ice production in the polynya ranges between 3 and 4 m. The probability of convective mixing penetrating down to the seafloor is highest in the regions of the flaw polynya, but does not exceed 20% in the Eastern and 70% in the Western Laptev Sea. Conductivity-temperature-depth (CTD) measurements and observations of currents carried out in April-May 1999 allowed us to investigate the surface circulation along the margins of the Laptev Sea flaw polynya. The convective nature of the surface currents, with velocities measured as high as 62 cm/s, is discussed. Currents are most likely part of circulation cells, which arise as a result of brine rejection due to intensive ice formation in the polynya. It is shown that the spatial alignment of sea ice crystals in the marginal part of the polynya is most likely a consequence of the quasi-stationary cellular circulation
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.gloplacha.2004.12.016
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