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  • 1
    Online Resource
    Online Resource
    Measurements beneath an Antarctic ice shelf using an autonomous underwater vehicle
    American Geophysical Union (AGU) ; 2006
    In:  Geophysical Research Letters Vol. 33, No. 8 ( 2006)
    Details
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 33, No. 8 ( 2006)
    Type of Medium: Online Resource
    ISSN: 0094-8276
    URL: Article
    DOI: 10.1029/2006GL025998
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2006
    detail.hit.zdb_id: 2021599-X
    detail.hit.zdb_id: 7403-2
    SSG: 16,13
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  • 2
    Online Resource
    Online Resource
    Interannual variability of Arctic sea ice export into the East Greenland Current
    American Geophysical Union (AGU) ; 2010
    In:  Journal of Geophysical Research: Oceans Vol. 115, No. C12 ( 2010-12)
    Details
    In: Journal of Geophysical Research: Oceans, American Geophysical Union (AGU), Vol. 115, No. C12 ( 2010-12)
    Abstract: Observations since the 1950s suggest that the Arctic climate system is changing in response to rising global air temperatures. These changes include an intensified hydrological cycle, Arctic sea ice decline, and increasing Greenland glacial melt. Here we use new δ 18 O data from the East Greenland Current system at Cape Farewell and Denmark Strait to determine the relative proportions of the freshwater components within the East Greenland Current and East Greenland Coastal Current. Through the comparison of these new data with historical studies, we gain insight into the changing Arctic freshwater balance. We detect three key shifts in the net freshwater component δ 18 O values, these are (1) a shift to lighter values in the late 1990s that possibly indicates an increased Greenland glacial melt or a reduced sea ice melt admixture and (2) a short‐term shift to a ∼10‰ heavier value in 2005 followed by (3) a shift back to the historic average value in 2008. The latter fluctuation reflects a short‐term dramatic rise and fall of sea ice meltwater addition into the East Greenland Current system. We infer that this anomalously large inclusion of sea ice meltwater resulted from a short‐term peak in Arctic sea ice export via Fram Strait. Our findings, therefore, suggest that the freshwater carried in the East Greenland Current system is susceptible to short‐term, high‐amplitude changes in the upstream freshwater balance, which may have important ramifications for the global thermohaline circulation through the suppression of deep water formation in the North Atlantic.
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2010JC006227
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2010
    detail.hit.zdb_id: 2033040-6
    detail.hit.zdb_id: 3094104-0
    detail.hit.zdb_id: 2130824-X
    detail.hit.zdb_id: 2016813-5
    detail.hit.zdb_id: 2016810-X
    detail.hit.zdb_id: 2403298-0
    detail.hit.zdb_id: 2016800-7
    detail.hit.zdb_id: 161666-3
    detail.hit.zdb_id: 161667-5
    detail.hit.zdb_id: 2969341-X
    detail.hit.zdb_id: 161665-1
    detail.hit.zdb_id: 3094268-8
    detail.hit.zdb_id: 710256-2
    detail.hit.zdb_id: 2016804-4
    detail.hit.zdb_id: 3094181-7
    detail.hit.zdb_id: 3094219-6
    detail.hit.zdb_id: 3094167-2
    detail.hit.zdb_id: 2220777-6
    detail.hit.zdb_id: 3094197-0
    SSG: 16,13
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  • 3
    Online Resource
    Online Resource
    Pathways and modification of warm water flowing beneath Thwaites Ice Shelf, West Antarctica
    American Association for the Advancement of Science (AAAS) ; 2021
    In:  Science Advances Vol. 7, No. 15 ( 2021-04-09)
    Details
    In: Science Advances, American Association for the Advancement of Science (AAAS), Vol. 7, No. 15 ( 2021-04-09)
    Abstract: Thwaites Glacier is the most rapidly changing outlet of the West Antarctic Ice Sheet and adds large uncertainty to 21st century sea-level rise predictions. Here, we present the first direct observations of ocean temperature, salinity, and oxygen beneath Thwaites Ice Shelf front, collected by an autonomous underwater vehicle. On the basis of these data, pathways and modification of water flowing into the cavity are identified. Deep water underneath the central ice shelf derives from a previously underestimated eastern branch of warm water entering the cavity from Pine Island Bay. Inflow of warm and outflow of melt-enriched waters are identified in two seafloor troughs to the north. Spatial property gradients highlight a previously unknown convergence zone in one trough, where different water masses meet and mix. Our observations show warm water impinging from all sides on pinning points critical to ice-shelf stability, a scenario that may lead to unpinning and retreat.
    Type of Medium: Online Resource
    ISSN: 2375-2548
    URL: Article
    DOI: 10.1126/sciadv.abd7254
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2021
    detail.hit.zdb_id: 2810933-8
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  • 4
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    Online Resource
    Warming of waters in an East Greenland fjord prior to glacier retreat: mechanisms and connection to large-scale atmospheric conditions
    Copernicus GmbH ; 2011
    In:  The Cryosphere Vol. 5, No. 3 ( 2011-09-09), p. 701-714
    Details
    In: The Cryosphere, Copernicus GmbH, Vol. 5, No. 3 ( 2011-09-09), p. 701-714
    Abstract: Abstract. Hydrographic data acquired in Kangerdlugssuaq Fjord and adjacent seas in 1993 and 2004 are used together with reanalysis from the NEMO ocean modelling framework to elucidate water-mass change and ice-ocean-atmosphere interactions in East Greenland. The hydrographic data show that the fjord contains warm subtropical waters and that fjord waters in 2004 were considerably warmer than in 1993. The ocean reanalysis shows that the warm properties of fjord waters in 2004 are related to a major peak in oceanic shoreward heat flux into a cross-shelf trough on the outer continental shelf. The heat flux into this trough varies according to seasonal exchanges with the atmosphere as well as from deep seasonal intrusions of subtropical waters. Both mechanisms contribute to high (low) shoreward heat flux when winds from the northeast are weak (strong). The combined effect of surface heating and inflow of subtropical waters is seen in the hydrographic data, which were collected after periods when along-shore coastal winds from the north were strong (1993) and weak (2004). The latter data were furthermore acquired during the early phase of a prolonged retreat of Kangerdlugssuaq Glacier. We show that coastal winds vary according to the pressure gradient defined by a semi-permanent atmospheric high-pressure system over Greenland and a persistent atmospheric low situated near Iceland. The magnitude of this pressure gradient is controlled by longitudinal variability in the position of the Icelandic Low.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    URL: Article
    DOI: 10.5194/tc-5-701-2011
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2011
    detail.hit.zdb_id: 2393169-3
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  • 5
    Online Resource
    Online Resource
    Increasing vertical mixing to reduce Southern Ocean deep convection in NEMO3.4
    Copernicus GmbH ; 2015
    In:  Geoscientific Model Development Vol. 8, No. 10 ( 2015-10-06), p. 3119-3130
    Details
    In: Geoscientific Model Development, Copernicus GmbH, Vol. 8, No. 10 ( 2015-10-06), p. 3119-3130
    Abstract: Abstract. Most CMIP5 (Coupled Model Intercomparison Project Phase 5) models unrealistically form Antarctic Bottom Water by open ocean deep convection in the Weddell and Ross seas. To identify the mechanisms triggering Southern Ocean deep convection in models, we perform sensitivity experiments on the ocean model NEMO3.4 forced by prescribed atmospheric fluxes. We vary the vertical velocity scale of the Langmuir turbulence, the fraction of turbulent kinetic energy transferred below the mixed layer, and the background diffusivity and run short simulations from 1980. All experiments exhibit deep convection in the Riiser-Larsen Sea in 1987; the origin is a positive sea ice anomaly in 1985, causing a shallow anomaly in mixed layer depth, hence anomalously warm surface waters and subsequent polynya opening. Modifying the vertical mixing impacts both the climatological state and the associated surface anomalies. The experiments with enhanced mixing exhibit colder surface waters and reduced deep convection. The experiments with decreased mixing give warmer surface waters, open larger polynyas causing more saline surface waters and have deep convection across the Weddell Sea until the simulations end. Extended experiments reveal an increase in the Drake Passage transport of 4 Sv each year deep convection occurs, leading to an unrealistically large transport at the end of the simulation. North Atlantic deep convection is not significantly affected by the changes in mixing parameters. As new climate model overflow parameterisations are developed to form Antarctic Bottom Water more realistically, we argue that models would benefit from stopping Southern Ocean deep convection, for example by increasing their vertical mixing.
    Type of Medium: Online Resource
    ISSN: 1991-9603
    URL: Article
    DOI: 10.5194/gmd-8-3119-2015
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2015
    detail.hit.zdb_id: 2456725-5
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  • 6
    Online Resource
    Online Resource
    Ice-shelf – ocean interactions at Fimbul Ice Shelf, Antarctica from oxygen isotope ratio measurements
    Copernicus GmbH ; 2008
    In:  Ocean Science Vol. 4, No. 1 ( 2008-03-05), p. 89-98
    Details
    In: Ocean Science, Copernicus GmbH, Vol. 4, No. 1 ( 2008-03-05), p. 89-98
    Abstract: Abstract. Melt water from the floating ice shelves at the margins of the southeastern Weddell Sea makes a significant contribution to the fresh water budget of the region. In February 2005 a multi-institution team conducted an oceanographic campaign at Fimbul Ice Shelf on the Greenwich Meridian as part of the Autosub Under Ice programme. This included a mission of the autonomous submarine Autosub 25 km into the cavity beneath Fimbul Ice Shelf, and a number of ship-based hydrographic sections on the continental shelf and adjacent to the ice shelf front. The measurements reveal two significant sources of glacial melt water at Fimbul Ice Shelf: the main cavity under the ice shelf and an ice tongue, Trolltunga, that protrudes from the main ice front and out over the continental slope into deep water. Glacial melt water is concentrated in a 200 m thick Ice Shelf Water (ISW) layer below the base of the ice shelf at 150–200 m, with a maximum glacial melt concentration of up to 1.16%. Some glacial melt is found throughout the water column, and much of this is from sources other than Fimbul Ice Shelf. However, at least 0.2% of the water in the ISW layer cannot be accounted for by other processes and must have been contributed by the ice shelf. Just downstream of Fimbul Ice Shelf we observe locally created ISW mixing out across the continental slope. The ISW formed here is much less dense than that formed in the southwest Weddell Sea, and will ultimately contribute a freshening (and reduction in δ18O) to the upper 100–150 m of the water column in the southeast Weddell Sea.
    Type of Medium: Online Resource
    ISSN: 1812-0792
    URL: Article
    DOI: 10.5194/os-4-89-2008
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2008
    detail.hit.zdb_id: 2183769-7
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  • 7
    Online Resource
    Online Resource
    Observations of oceanic mesoscale features and variability in the Canary Islands area from ERS-1 altimeter data, satellite infrared imagery and hydrographic measurements
    Informa UK Limited ; 2002
    In:  International Journal of Remote Sensing Vol. 23, No. 22 ( 2002-01), p. 4897-4916
    Details
    In: International Journal of Remote Sensing, Informa UK Limited, Vol. 23, No. 22 ( 2002-01), p. 4897-4916
    Type of Medium: Online Resource
    ISSN: 0143-1161 , 1366-5901
    URL: Article
    DOI: 10.1080/01431160110034681
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2002
    detail.hit.zdb_id: 1497529-4
    detail.hit.zdb_id: 754117-X
    SSG: 14
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  • 8
    Online Resource
    Online Resource
    Wind forcing of salinity anomalies in the Denmark Strait overflow
    Copernicus GmbH ; 2011
    In:  Ocean Science Vol. 7, No. 6 ( 2011-11-30), p. 821-834
    Details
    In: Ocean Science, Copernicus GmbH, Vol. 7, No. 6 ( 2011-11-30), p. 821-834
    Abstract: Abstract. The overflow of dense water from the Nordic Seas to the North Atlantic through Denmark Strait is an important part of the global thermohaline circulation. The salinity of the overflow plume has been measured by an array of current meters across the continental slope off the coast of Angmagssalik, southeast Greenland since September 1998. During 2004 the salinity of the overflow plume changed dramatically; the entire width of the array (70 km) freshened between January 2004 and July 2004, with a significant negative salinity anomaly of about 0.06 in May. The event in May represents a fresh anomaly of over 3 standard deviations from the mean since recording began in 1998. The OCCAM 1/12° Ocean General Circulation Model not only reproduces the 2004 freshening event (r=0.96, p〈0.01), but also correlates well with salinity observations over a previous 6 year period (r=0.54, p〈0.01), despite the inevitable limitations of a z-coordinate model in representing the mixing processes at and downstream of the Denmark Strait sill. Consequently the physical processes causing the 2004 anomaly and prior variability in salinity are investigated using the model output. Our results reject the hypotheses that the anomaly is caused by processes occurring between the overflow sill and the moorings, or by an increase in upstream net freshwater input. Instead, we show that the 2004 salinity anomaly is caused by an increase in volume flux of low salinity water, with a potential density greater than 27.60 kg m−3, flowing towards the Denmark Strait sill in the East Greenland Current. This is caused by an increase in southward wind stress upstream of the sill at around 75° N 20° W four and a half months earlier, and an associated strengthening of the East Greenland Current.
    Type of Medium: Online Resource
    ISSN: 1812-0792
    URL: Article
    DOI: 10.5194/os-7-821-2011
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2011
    detail.hit.zdb_id: 2183769-7
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  • 9
    Online Resource
    Online Resource
    On the outflow of dense water from the Weddell and Ross Seas in OCCAM model
    Copernicus GmbH ; 2012
    In:  Ocean Science Vol. 8, No. 3 ( 2012-06-14), p. 369-388
    Details
    In: Ocean Science, Copernicus GmbH, Vol. 8, No. 3 ( 2012-06-14), p. 369-388
    Abstract: Abstract. We describe the seasonal and interannual variability of volume transports in the Weddell and Ross Seas using the 1/12° 20-yr simulation of the OCCAM global ocean general circulation model. The average simulated full-depth cumulative volume transports were 28.5 ± 2.9 Sv (1 Sv ≡ 106 m3 s−1) and 13.4 ± 5.2 Sv, across the main export regions of the Weddell and Ross Seas, respectively. The values of mean outflow of Antarctic Bottom Water (AABW) (defined by neutral density γn ≥ 28.27 kg m−3) from the Weddell and Ross Seas of 10.6 ± 3.1 Sv and 0.5 ± 0.7 Sv, respectively, agree with the range reported in historical observational studies. The export of Weddell Sea dense water in OCCAM is primarily determined by the strength of the Weddell Gyre. Variability in AABW export is predominantly at periods of ~1 yr and 2–4 yr.
    Type of Medium: Online Resource
    ISSN: 1812-0792
    URL: Article
    DOI: 10.5194/os-8-369-2012
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2183769-7
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  • 10
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    Online Resource
    An Overview of the Synoptic Antarctic Shelf-Slope Interactions (SASSI) project for the International Polar Year
    Copernicus GmbH ; 2012
    In:  Ocean Science Vol. 8, No. 6 ( 2012-12-19), p. 1111-1116
    Details
    In: Ocean Science, Copernicus GmbH, Vol. 8, No. 6 ( 2012-12-19), p. 1111-1116
    Type of Medium: Online Resource
    ISSN: 1812-0792
    URL: Article
    DOI: 10.5194/os-8-1111-2012
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2012
    detail.hit.zdb_id: 2183769-7
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