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David G. Barber - One of the best experts on this subject based on the ideXlab platform.

  • Shelfbreak current over the Canadian Beaufort Sea continental slope: Wind-driven events in January 2005
    Journal of Geophysical Research: Oceans, 2016
    Co-Authors: Igor Dmitrenko, Jennifer V. Lukovich, Sergei Kirillov, Alexandre Forest, Yves Gratton, Denis Volkov, William J. Williams, Claude Bélanger, David G. Barber
    Abstract:

    The shelfbreak current over the Beaufort Sea continental slope is known to be one of the most energetic features of the Beaufort Sea hydrography. In January 2005, three oceanographic moorings deployed over the Canadian (eastern) Beaufort Sea continental slope simultaneously recorded two consecutive shelfbreak current events with along-slope eastward bottom-intensified flow up to 120 cm s−1. Both events were generated by the local wind forcing associated with two Pacific-born cyclones passing north of the Beaufort Sea continental slope toward the Canadian Archipelago. Over the mooring array, the associated westerly wind exceeded 15 m s−1. These two cyclones generated storm surges along the Beaufort Sea coast with Sea surface height (SSH) rising up to 1.4 m following the two westerly wind maxima. We suggest that the westerly along-slope wind generated a surface Ekman onshore transport. The associated SSH increase over the shelf produced a cross-slope pressure gradient that drove an along-slope eastward geostrophic current, in the same direction as the wind. This wind-driven barotropic flow was superimposed on the background baroclinic bottom-intensified shelfbreak current that consequently amplified. Summer-fall satellite altimetry data for 1992–2013 show that the SSH gradient in the southeastern Beaufort Sea is enhanced over the upper continental slope in response to frequent storm surge events. Because the local wind forcing and/or Sea-ice drift could not explain the reduction of Sea-ice concentration over the Beaufort Sea continental slope in January 2005, we speculate that wind-driven Sea level fluctuations may impact the Sea-ice cover in winter.

  • Atmospheric forcing of the Beaufort Sea ice gyre: Surface-stratosphere coupling
    Journal of Geophysical Research, 2009
    Co-Authors: Jennifer V. Lukovich, M. G. Asplin, David G. Barber
    Abstract:

    [1] In a companion article we examined the nature of correspondence between synoptic weather patterns and reversals in the Beaufort Sea ice gyre. In this paper we extend this analysis to examine the role of stratospheric forcing on surface phenomena. Investigated in particular is the correspondence between reversals in stratospheric winds at 10 mbar during winter as defined by stratospheric sudden warmings (SSW) and mean Sea level pressure synoptic types in the Beaufort Sea region. Connections between stratospheric and surface events are characterized using relative vorticity and the square of strain computed at different pressure levels from the stratosphere to the surface in the Beaufort Sea region. We quantify the correspondence between stratospheric flow and surface phenomena through investigation of the frequency in synoptic types derived in a companion article during stratospheric sudden warming events. Investigation of stratospheric wind gradients averaged over the Beaufort Sea region demonstrates a prevalence in anticyclonic activity during SSWs that persists for approximately 20 days. Examination of the evolution in synoptic types in the Beaufort Sea region also shows an increase in the number of synoptic types associated with anticyclonic activity during SSWs.

  • Atmospheric controls on Sea ice motion in the southern Beaufort Sea
    Journal of Geophysical Research, 2006
    Co-Authors: Jennifer V. Lukovich, David G. Barber
    Abstract:

    [1] The Beaufort Sea ice gyre is characterized in winter months by an anticyclonic regime associated with Sea level pressure (SLP) highs. Previous studies have shown instances of a reversal in this regime in summer months with the arrival of SLP lows over the Beaufort Sea, while also demonstrating a link to variations in lower stratospheric potential vorticity. In this study we examine the role of relative vorticity in describing dynamic variability on weekly timescales from the surface to the middle stratosphere. Results from this analysis show that the Beaufort Gyre is characterized predominantly by anticyclonic activity throughout the year for the time interval considered (from 1979 to 2000), with a summer reversal to cyclonic activity, whose strength and duration varies between years. These reversals coincide with reversals in SLP based on a correlation analysis. Comparison of ice and atmospheric relative vorticity fields in the Beaufort Sea region (BSR) for all weeks from 1979 to 2000 indicates that Sea ice and lower tropospheric processes are anticorrelated at zero time lag. This is in contrast to relative vorticity fields at 10 mbar, which exhibit maximum correlation between stratospheric and Sea ice responses when 10 mbar leads ice relative vorticity by 2–6 weeks.

Jennifer V. Lukovich - One of the best experts on this subject based on the ideXlab platform.

  • Shelfbreak current over the Canadian Beaufort Sea continental slope: Wind-driven events in January 2005
    Journal of Geophysical Research: Oceans, 2016
    Co-Authors: Igor Dmitrenko, Jennifer V. Lukovich, Sergei Kirillov, Alexandre Forest, Yves Gratton, Denis Volkov, William J. Williams, Claude Bélanger, David G. Barber
    Abstract:

    The shelfbreak current over the Beaufort Sea continental slope is known to be one of the most energetic features of the Beaufort Sea hydrography. In January 2005, three oceanographic moorings deployed over the Canadian (eastern) Beaufort Sea continental slope simultaneously recorded two consecutive shelfbreak current events with along-slope eastward bottom-intensified flow up to 120 cm s−1. Both events were generated by the local wind forcing associated with two Pacific-born cyclones passing north of the Beaufort Sea continental slope toward the Canadian Archipelago. Over the mooring array, the associated westerly wind exceeded 15 m s−1. These two cyclones generated storm surges along the Beaufort Sea coast with Sea surface height (SSH) rising up to 1.4 m following the two westerly wind maxima. We suggest that the westerly along-slope wind generated a surface Ekman onshore transport. The associated SSH increase over the shelf produced a cross-slope pressure gradient that drove an along-slope eastward geostrophic current, in the same direction as the wind. This wind-driven barotropic flow was superimposed on the background baroclinic bottom-intensified shelfbreak current that consequently amplified. Summer-fall satellite altimetry data for 1992–2013 show that the SSH gradient in the southeastern Beaufort Sea is enhanced over the upper continental slope in response to frequent storm surge events. Because the local wind forcing and/or Sea-ice drift could not explain the reduction of Sea-ice concentration over the Beaufort Sea continental slope in January 2005, we speculate that wind-driven Sea level fluctuations may impact the Sea-ice cover in winter.

  • Atmospheric forcing of the Beaufort Sea ice gyre: Surface-stratosphere coupling
    Journal of Geophysical Research, 2009
    Co-Authors: Jennifer V. Lukovich, M. G. Asplin, David G. Barber
    Abstract:

    [1] In a companion article we examined the nature of correspondence between synoptic weather patterns and reversals in the Beaufort Sea ice gyre. In this paper we extend this analysis to examine the role of stratospheric forcing on surface phenomena. Investigated in particular is the correspondence between reversals in stratospheric winds at 10 mbar during winter as defined by stratospheric sudden warmings (SSW) and mean Sea level pressure synoptic types in the Beaufort Sea region. Connections between stratospheric and surface events are characterized using relative vorticity and the square of strain computed at different pressure levels from the stratosphere to the surface in the Beaufort Sea region. We quantify the correspondence between stratospheric flow and surface phenomena through investigation of the frequency in synoptic types derived in a companion article during stratospheric sudden warming events. Investigation of stratospheric wind gradients averaged over the Beaufort Sea region demonstrates a prevalence in anticyclonic activity during SSWs that persists for approximately 20 days. Examination of the evolution in synoptic types in the Beaufort Sea region also shows an increase in the number of synoptic types associated with anticyclonic activity during SSWs.

  • Atmospheric controls on Sea ice motion in the southern Beaufort Sea
    Journal of Geophysical Research, 2006
    Co-Authors: Jennifer V. Lukovich, David G. Barber
    Abstract:

    [1] The Beaufort Sea ice gyre is characterized in winter months by an anticyclonic regime associated with Sea level pressure (SLP) highs. Previous studies have shown instances of a reversal in this regime in summer months with the arrival of SLP lows over the Beaufort Sea, while also demonstrating a link to variations in lower stratospheric potential vorticity. In this study we examine the role of relative vorticity in describing dynamic variability on weekly timescales from the surface to the middle stratosphere. Results from this analysis show that the Beaufort Gyre is characterized predominantly by anticyclonic activity throughout the year for the time interval considered (from 1979 to 2000), with a summer reversal to cyclonic activity, whose strength and duration varies between years. These reversals coincide with reversals in SLP based on a correlation analysis. Comparison of ice and atmospheric relative vorticity fields in the Beaufort Sea region (BSR) for all weeks from 1979 to 2000 indicates that Sea ice and lower tropospheric processes are anticorrelated at zero time lag. This is in contrast to relative vorticity fields at 10 mbar, which exhibit maximum correlation between stratospheric and Sea ice responses when 10 mbar leads ice relative vorticity by 2–6 weeks.

J. R. Dietrich - One of the best experts on this subject based on the ideXlab platform.

  • CRUSTAL STRUCTURE AND TECTONICS OF THE SOUTHEASTERN Beaufort Sea CONTINENTAL-MARGIN
    Tectonics, 1994
    Co-Authors: Randell Stephenson, K. C. Coflin, Larry S. Lane, J. R. Dietrich
    Abstract:

    The structure of the southeast margin of the Canada Basin is synthesized from seismic reflection and refraction profiles in the southern Beaufort Sea and Mackenzie Delta, interpreted in conjunction with potential field data and the exploration seismic data base. The present margin was formed in the Jura-Cretaceous and comprises a complex pattern of rifted and transform faulted crustal segments. Thinning in the upper crust is bounded by the Eskimo Lakes Fault Zone (ELFZ), a series of extensional listric normal faults, and is controlled by preexisting structures. Lower crustal thinning and the transition to oceanic crust occurs outboard of the ELFZ. A thick (up to 16 km) Late Jurassic and younger synrift and postrift sedimentary succession overlies oceanic crust in the eastern part of the Canadian Beaufort Sea and thinned continental crust between the Mackenzie Delta and Alaska. Tertiary faulting in the sedimentary basin appears to be related to the crustal structure. Present-day seismicity in the southern Beaufort Sea is essentially limited to the area underlain by oceanic crust. Abrupt along-strike changes in crustal affinity and degree of thinning allow the recognition of a NW-trending transform fault. Regional gravity data, dominated by a series of coastline parallel highs, are used to extrapolate crustal features to the northeast along the Canadian polar continental margin. It is inferred that the Canadian polar margin consists of a number of 250-to-350-km-long stretched crustal segments separated by possible fracture zones. The orientation of the analogous tranform fault identified in the southeastern Beaufort Sea offers the possibility of kinematic constraints on models of ocean floor development within Canada Basin.

Sheldon Drobot - One of the best experts on this subject based on the ideXlab platform.

  • interannual variability in summer Beaufort Sea ice conditions relationship to winter and summer surface and atmospheric variability
    Journal of Geophysical Research, 2003
    Co-Authors: Sheldon Drobot, J A Maslanik
    Abstract:

    [1] Interannual variations in the Beaufort Sea summer ice cover influence climatic, ecological, and socioeconomic conditions. Utilizing an ice severity index based on the distance from Point Barrow, Alaska, to the ice edge and characteristics of the shipping Season, variations in summer ice conditions are examined from 1953 through 2000 with respect to variations in winter and summer surface and meteorological conditions. Although there is no significant trend in the ice severity index, ice conditions during the 1990s were less severe than in previous decades. Interannual variations in summer ice conditions are related to dynamical mechanisms in the preceding winter and dynamical and thermodynamical processes during summer. In winters preceding light ice summers, high pressure develops over Siberia, leading to increased ice transport across the Transpolar Drift Stream, while the Beaufort Gyre is diminished, resulting in decreased multiyear ice transport into the Beaufort Sea. Air temperatures are also elevated near the Alaskan North Slope, but there is little difference in winter air temperature over the Beaufort Sea. During light ice summers the Beaufort High is strongly defined over the Canadian Arctic Archipelago, enhancing easterly and northerly winds and advecting Sea ice out of the Beaufort Sea. Above-normal air temperatures also occur over much of the southern Beaufort Sea. Variations in Sea level pressure and winds that result in light and heavy ice summers are closely linked to positive and negative winter Arctic Oscillation/North Atlantic Oscillation phases, as well as negative and positive summer Arctic Oscillation/North Atlantic Oscillation phases.

G. W. K. Moore - One of the best experts on this subject based on the ideXlab platform.

  • Decadal variability and a recent amplification of the summer Beaufort Sea High
    Geophysical Research Letters, 2012
    Co-Authors: G. W. K. Moore
    Abstract:

    [1] The Beaufort Sea High (BSH), an anti-cyclone over the Beaufort Sea, is an important feature of the summer atmospheric circulation over the Arctic Ocean. For example, years characterized by low Arctic Sea ice extent are typically associated with the presence of a stronger BSH; with the opposite occurring during years with high Sea ice extent. In this paper, we show that there exists variability on the decadal time scale in the intensity and location of the summer BSH. We also show that there has been a trend towards a stronger summer BSH that began in the late 1990s. This trend is shown to be coincident with a tendency towards a reduction in cyclogenesis during the summer over the Beaufort Sea. We argue that that these trends are the result of a warming of the troposphere in the western Arctic and the concomitant reduction in baroclincity.