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  • 1
    Publication Date: 2019-09-23
    Description: The water mass structure of the Arctic Ocean is remarkable, for its intermediate (depth range ~150–900 m) layer is filled with warm (temperature 〉0°C) and salty water of Atlantic origin (usually called the Atlantic Water, AW). This water is carried into and through the Arctic Ocean by the pan-Arctic boundary current, which moves cyclonically along the basins’ margins (Fig. 1). This system provides the largest input of water, heat, and salt into the Arctic Ocean; the total quantity of heat is substantial, enough to melt the Arctic sea ice cover several times over. By utilizing an extensive archive of recently collected observational data, this study provides a cohesive picture of recent large-scale changes in the AW layer of the Arctic Ocean. These recent observations show the warm pulse of AW that entered the Arctic Ocean in the early 1990s finally reached the Canada Basin during the 2000s. The second warm pulse that entered the Arctic Ocean in the mid-2000s has moved through the Eurasian Basin and is en route downstream. One of the most intriguing results of these observations is the realization of the possibility of uptake of anomalous AW heat by overlying layers, with possible implications for an already-reduced Arctic ice cover.
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Publication Date: 2022-01-31
    Description: This study is focused on the specific features of ocean–air interaction in the Laptev Sea, in the late summer, on the basis of recurrent measurements during four expeditions in the 2000s and 2010s, atmospheric reanalysis products, and satellite ice concentration data. It was established that in the “icy” years, the accumulation of heat in the upper ocean layer is insignificant for the subsequent ice formation. In the “ice-free” years, the accumulated heat storage in the upper mixed layer depends on the duration of open water and the distance of the point of interest to the nearest ice edge. In a broader context, we considered possible links between the average ice area/extent in the August–September–October (ASO) period, and in the December–January–February (DJF) period, for two representative Arctic regions; that is, the Eurasian segment, defined within the bounds 60–120° E, 65–80° N, and the American segment, defined within the bounds 150° E–150° W, 65–80° N. Significant “seasonal memory”, characterized by the consistent change of the ice cover parameters in sequential seasons, was revealed in the Eurasian segment between 2007 and 2017. No linkage on a seasonal time scale was found in the American segment. A possible explanation for the distinguished contrast between the two geographical regions is proposed
    Type: Article , PeerReviewed
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  • 3
    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
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  • 4
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    AWI
    In:  EPIC3POLEX, annual meeting, Potsdam (virtual meeting), Germany, 2020-09-29-2020-10-01Potsdam, AWI
    Publication Date: 2020-11-06
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 5
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    American Geophysical Union
    In:  EPIC3Journal of Geophysical Research: Oceans, American Geophysical Union, ISSN: 2169-9275
    Publication Date: 2018-09-20
    Description: Gradually decaying Arctic sea ice changes the boundary conditions at the surface, separating ocean and atmosphere. In recent years, substantial reductions in sea ice during winter have been observed in the Atlantic sector of the Arctic Ocean, which forms the gateway for warm water inflow from the midlatitudes. In this study, we used routine output from the Mercator Ocean global operational system (MOGOS) to assess the efficiency of winter thermohaline convection transporting heat from deep layers to the ocean surface along the Atlantic origin water (AW) pathway, between Svalbard and Franz Joseph Land in the Nansen Basin. Positive temperature extremes in the AW layer in midwinter promote favorable prerequisite conditions for deep‐reaching thermohaline convection, with explicit signs captured by the MOGOS. Balance equations with several assumptions for the compact region around the position (81.30°N, 31°E) of the long‐term (2004–2010) mooring demonstrated that winter heat loss at the ocean surface is mainly compensated by convective heat flux from the AW layer. Heat and salt fluxes, associated with horizontal advection, are compatible with convective fluxes, while contribution of ice formation/melt is substantially smaller. Conclusion about the dominant role of vertical convection in shaping thermohaline structure and reducing sea ice in winter is supported by correlation analysis of the MOGOS output and mooring‐based measurements. Unfavorable background conditions (thick and consolidated sea ice in combination with specific directions of ice drift) may significantly alter convection development, as demonstrated for two sequential years with substantially different external forcing.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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