ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Insights from Antarctica on volcanic forcing during the Common Era (2014)
    Macmillan Publishers Limited
    In:  EPIC3Nature Climate Change, Macmillan Publishers Limited, 4(8), pp. 693-697, ISSN: 1758-678X
    Details
    Publication Date: 2016-11-14
    Description: Assessments of climate sensitivity to projected greenhouse gas concentrations underpin environmental policy decisions, with such assessments often based on model simulations of climate during recent centuries and millennia1, 2, 3. These simulations depend critically on accurate records of past aerosol forcing from global-scale volcanic eruptions, reconstructed from measurements of sulphate deposition in ice cores4, 5, 6. Non-uniform transport and deposition of volcanic fallout mean that multiple records from a wide array of ice cores must be combined to create accurate reconstructions. Here we re-evaluated the record of volcanic sulphate deposition using a much more extensive array of Antarctic ice cores. In our new reconstruction, many additional records have been added and dating of previously published records corrected through precise synchronization to the annually dated West Antarctic Ice Sheet Divide ice core7, improving and extending the record throughout the Common Era. Whereas agreement with existing reconstructions is excellent after 1500, we found a substantially different history of volcanic aerosol deposition before 1500; for example, global aerosol forcing values from some of the largest eruptions (for example, 1257 and 1458) previously were overestimated by 20–30% and others underestimated by 20–50%.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 2
    facet.materialart.
    Unknown
    Characterization and formation of melt layers in polar snow : observations and experiments from West Antarctica (2010)
    International Glaciological Society
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © International Glaciological Society, 2005. This article is posted here by permission of International Glaciological Society for personal use, not for redistribution. The definitive version was published in Journal of Glaciology 51 (2005): 307-312, doi:10.3189/172756505781829395.
    Description: Surface melting rarely occurs across most of the Antarctic ice sheet, away from the warmer coastal regions. Nonetheless, isolated melt features are preserved in the firn and ice in response to infrequent and short-lived melting events. An understanding of the formation and occurrence of these melt layers will help us to interpret records of past melt occurrences from polar ice cores such as the Siple Dome ice-core record from West Antarctica. A search in the near-surface firn in West Antarctica found that melt features are extremely rare, and consist of horizontal, laterally continuous, one to a few millimeter thick, ice layers with few air bubbles. The melt layers found date from the 1992/93 and 1991/92 summers. Field experiments to investigate changes in stratigraphy taking place during melt events reproduced melt features as seen in the natural stratigraphy. Melting conditions of varying intensity were created by passively heating the near-surface air for varying lengths of time inside a clear plastic hotbox. Melt layers formed due entirely to preferential flow and subsequent refreezing of meltwater from the surface into near-surface, fine-grained, crust layers. Continuous melt layers were formed experimentally when positive-degree-day values exceeded 18C-day, a value corresponding well with air-temperature records from automatic weather station sites where melt layers formed in the recent past.
    Description: This research was supported by NASA grant NAG5-7776 and by US National Science Foundation grant OPP-9814485 to The Pennsylvania State University, and by a NASA Earth System Science Fellowship to S.B. Das.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 3
    facet.materialart.
    Unknown
    Constraining the recent mass balance of Pine Island and Thwaites glaciers, West Antarctica, with airborne observations of snow accumulation (2014)
    Copernicus Publications on behalf of the European Geosciences Union
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cryosphere 8 (2014): 1375-1392, doi:10.5194/tc-8-1375-2014.
    Description: In Antarctica, uncertainties in mass input and output translate directly into uncertainty in glacier mass balance and thus in sea level impact. While remotely sensed observations of ice velocity and thickness over the major outlet glaciers have improved our understanding of ice loss to the ocean, snow accumulation over the vast Antarctic interior remains largely unmeasured. Here, we show that an airborne radar system, combined with ice-core glaciochemical analysis, provide the means necessary to measure the accumulation rate at the catchment-scale along the Amundsen Sea coast of West Antarctica. We used along-track radar-derived accumulation to generate a 1985–2009 average accumulation grid that resolves moderate- to large-scale features (〉25 km) over the Pine Island–Thwaites glacier drainage system. Comparisons with estimates from atmospheric models and gridded climatologies generally show our results as having less accumulation in the lower-elevation coastal zone but greater accumulation in the interior. Ice discharge, measured over discrete time intervals between 1994 and 2012, combined with our catchment-wide accumulation rates provide an 18-year mass balance history for the sector. While Thwaites Glacier lost the most ice in the mid-1990s, Pine Island Glacier's losses increased substantially by 2006, overtaking Thwaites as the largest regional contributor to sea-level rise. The trend of increasing discharge for both glaciers, however, appears to have leveled off since 2008.
    Description: This research was supported at UW by NSF OPP grants ANT-0631973 (B Medley, I. Joughin, E. J. Steig, and H. Conway) and ANT-0424589 (B. Medley and I. Joughin). Work at WHOI was supported by NSF OPP grant ANT-0632031 and NASA grant NNX10AP09G (S. B. Das and A. S. Criscitiello). D. H. Bromwich and J. P. Nicolas were supported by NASA grant NN12XAI29G and NSF grant ANT-1049089.
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 4
    facet.materialart.
    Unknown
    Rise in frequency of surface melting at Siple Dome through the Holocene : evidence for increasing marine influence on the climate of West Antarctica (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): D02112, doi:10.1029/2007JD008790.
    Description: A new melt layer history from Siple Dome, West Antarctica, indicates notable late-Holocene summertime warming. Visual stratigraphic analyses of the 1004-m ice core identified 62 years with melt layers. Melting events began around 11.7 ka, followed by a period of no melting from 8.8–6.6 ka. Melt layer frequency increased from 6.6 ka to the present, with the 1000-year-average melt layer frequency reaching a maximum of 2% at 0.8 ka. We use our millennial-scale archive of melt events as a unique seasonal paleothermometer to elucidate changes in West Antarctic Holocene summer climate. Our calibration suggests the change in melt frequency from 0% to 2% may represent a summer temperature increase of ≥2°C from the middle to late Holocene. This temperature change cannot be explained entirely by local change in ice elevation or summer insolation and is in contrast to East Antarctic climate records, which show peak warmth in the early Holocene followed by stable or decreasing temperature. We interpret the rise in melt frequency as evidence of an increasing marine influence on the Ross Sea sector of West Antarctica. Although the surface elevation of Siple Dome has not changed greatly, the continued lateral retreat of the West Antarctic ice sheet from its Last Glacial Maximum configuration (across the outer continental shelf), and the delayed drawdown in ice thickness from the adjacent coastal Marie Byrd Land region, in conjunction with periods of increased cyclogenesis, perhaps related to variations in ENSO, would allow a moderated maritime climate to more easily reach West Antarctica.
    Description: This research was supported by NSF grant OPP-9814485 and NASA grant NAG5-7776 to Penn State University and by a NASA Earth System Science Graduate Fellowship and a WHOI Postdoctoral Scholar Fellowship to S. Das. Additional support to R. Alley at PSU is from NSF grants 0440899, 0440447, and 0424589 and the Comer Science and Education Foundation.
    Keywords: Siple Dome ; Melt layer record ; Antarctica Holocene climate
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 5
    facet.materialart.
    Unknown
    Molecular characterization of dissolved organic matter associated with the Greenland ice sheet (2010)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 74 (2010): 3768-3784, doi:10.1016/j.gca.2010.03.035.
    Description: Subsurface microbial oxidation of overridden soils and vegetation beneath glaciers and ice sheets may affect global carbon budgets on glacial-interglacial timescales. The likelihood and magnitude of this process depends on the chemical nature and reactivity of the subglacial organic carbon stores. We examined the composition of carbon pools associated with different regions of the Greenland ice sheet (subglacial, supraglacial, proglacial) in order to elucidate the type of dissolved organic matter (DOM) present in the subglacial discharge over a melt season. Electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry coupled to multivariate statistics permitted unprecedented molecular level characterization of this material and revealed that carbon pools associated with discrete glacial regions are comprised of different compound classes. Specifically, a larger proportion of protein-like compounds were observed in the supraglacial samples and in the early melt season (spring) subglacial discharge. In contrast, the late melt season (summer) subglacial discharge contained a greater fraction of lignin-like and other material presumably derived from underlying vegetation and soil. These results suggest (1) that the majority of supraglacial DOM originates from autochthonous microbial processes on the ice sheet surface, (2) that the subglacial DOM contains allochthonous carbon derived from overridden soils and vegetation as well as autochthonous carbon derived from in situ microbial metabolism, and (3) that the relative contribution of allochthonous and autochthonous material in subglacial discharge varies during the melt season. These conclusions are consistent with the hypothesis that, given sufficient time (e.g., overwinter storage), resident subglacial microbial communities may oxidize terrestrial material beneath the Greenland ice sheet.
    Description: This research was supported by: the National Science Foundation (CAREER-OCE- 0529101 (EBK), ARC-0520077 (SBD)), National Atmospheric and Space Administration (SBD), the WHOI Clark Arctic Research Initiative (EBK, SBD, MAC), the WHOI Ocean Ventures Fund (MPB), and the National and Science Engineering Research Council of Canada (MPB).
    Keywords: Glacier ; Ultrahigh resolution mass spectrometry ; FT-ICR ; Organic carbon ; DOM
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 6
    facet.materialart.
    Unknown
    Antarctic surface melting dynamics : enhanced perspectives from radar scatterometer data (2012)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): F02023, doi:10.1029/2011JF002126.
    Description: Antarctic ice sheet surface melting can regionally influence ice shelf stability, mass balance, and glacier dynamics, in addition to modulating near-surface physical and chemical properties over wide areas. Here, we investigate variability in surface melting from 1999 to 2009 using radar backscatter time series from the SeaWinds scatterometer aboard the QuikSCAT satellite. These daily, continent-wide observations are explored in concert with in situ meteorological records to validate a threshold-based melt detection method. Radar backscatter decreases during melting are significantly correlated with in situ positive degree-days as well as meltwater production determined from energy balance modeling at Neumayer Station, East Antarctica. These results support the use of scatterometer data as a diagnostic indicator of melt intensity (i.e., the relative liquid water production during melting). Greater spatial and temporal melting detected relative to previous passive microwave-based studies is attributed to a higher sensitivity of the scatterometer instrument. Continental melt intensity variability can be explained in part by the dynamics of the Southern Annular Mode and the Southern Oscillation Index, and extreme melting events across the Ross Ice Shelf region may be associated with El Niño conditions. Furthermore, we find that the Antarctic Peninsula accounts for only 20% of Antarctic melt extent but greater than 50% of the total Antarctic melt intensity. Over most areas, annual melt duration and intensity are proportional. However, regional and localized distinctions exist where the melt intensity metric provides greater insight into melting dynamics than previously obtainable with other remote sensing techniques.
    Description: Support for this research was provided by NASA grant NNX10AP09G and NSF grant ANT-063203.
    Description: 2012-11-17
    Keywords: Antarctica ; Melt intensity ; Remote sensing ; Surface melting
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: text/plain
    Format: application/postscript
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 7
    facet.materialart.
    Unknown
    Ice sheet record of recent sea-ice behavior and polynya variability in the Amundsen Sea, West Antarctica (2013)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 118 (2013): 118–130, doi:10.1029/2012JC008077.
    Description: Our understanding of past sea-ice variability is limited by the short length of satellite and instrumental records. Proxy records can extend these observations but require further development and validation. We compare methanesulfonic acid (MSA) and chloride (Cl–) concentrations from a new firn core from coastal West Antarctica with satellite-derived observations of regional sea-ice concentration (SIC) in the Amundsen Sea (AS) to evaluate spatial and temporal correlations from 2002–2010. The high accumulation rate (~39 g∙cm–2∙yr–1) provides monthly resolved records of MSA and Cl–, allowing detailed investigation of how regional SIC is recorded in the ice-sheet stratigraphy. Over the period 2002–2010 we find that the ice-sheet chemistry is significantly correlated with SIC variability within the AS and Pine Island Bay polynyas. Based on this result, we evaluate the use of ice-core chemistry as a proxy for interannual polynya variability in this region, one of the largest and most persistent polynya areas in Antarctica. MSA concentrations correlate strongly with summer SIC within the polynya regions, consistent with MSA at this site being derived from marine biological productivity during the spring and summer. Cl– concentrations correlate strongly with winter SIC within the polynyas as well as some regions outside the polynyas, consistent with Cl– at this site originating primarily from winter sea-ice formation. Spatial correlations were generally insignificant outside of the polynya areas, with some notable exceptions. Ice-core glaciochemical records from this dynamic region thus may provide a proxy for reconstructing AS and Pine Island Bay polynya variability prior to the satellite era.
    Description: This research was supported by an award from the Department of Energy Office of Science Graduate Fellowship Program (DOE SCGF) to ASC, a James E. and Barbara V. Moltz Research Fellowship to SBD, and by grants from NSF-OPP (#ANT-0632031 & #ANT-0631973); NSF-MRI (#EAR-1126217); NASA Cryosphere Program (#NNX10AP09G); and a WHOI Andrew W. Mellon Foundation Award for Innovative Research.
    Description: 2013-07-25
    Keywords: Sea ice ; Polynyas ; Antarctica ; Amundsen Sea ; Pine Island Bay ; Methanesulfonic acid
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 8
    facet.materialart.
    Unknown
    Airborne-radar and ice-core observations of annual snow accumulation over Thwaites Glacier, West Antarctica confirm the spatiotemporal variability of global and regional atmospheric models (2013)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 40 (2013): 3649–3654, doi:10.1002/grl.50706.
    Description: We use an airborne-radar method, verified with ice-core accumulation records, to determine the spatiotemporal variations of snow accumulation over Thwaites Glacier, West Antarctica between 1980 and 2009. We also present a regional evaluation of modeled accumulation in Antarctica. Comparisons between radar-derived measurements and model outputs show that three global models capture the interannual variability well (r 〉 0.9), but a high-resolution regional model (RACMO2) has better absolute accuracy and captures the observed spatial variability (r = 0.86). Neither the measured nor modeled accumulation records over Thwaites Glacier show any trend since 1980. Although an increase in accumulation may potentially accompany the observed warming in the region, the projected trend is too small to detect over the 30 year record.
    Description: This research was supported at UW by NSF OPP grants ANT-0631973 (B.M., I.J., E.J.S., and H.C.) and ANT-0424589 (B.M. and I.J.) and at WHOI by ANT-0632031 (S.B.D. and A.S.C.). D.H.B. and J.P.N. were supported by NASA grant NN12XAI29G. We acknowledge the work by the CReSIS team that went into developing the snow-radar system, which was partially supported with by NASA grant NNX10AT68G and by NSF OPP grant ANT-0424589 awarded to S.P.
    Description: 2014-01-26
    Keywords: West Antarctica ; Snow accumulation ; Airborne radar ; Firn
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: text/plain
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 9
    facet.materialart.
    Unknown
    Influence of ice-sheet geometry and supraglacial lakes on seasonal ice-flow variability (2013)
    Copernicus Publications on behalf of the European Geosciences Union
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in The Cryosphere 7 (2013): 1185-1192, doi:10.5194/tc-7-1185-2013.
    Description: Supraglacial lakes play an important role in establishing hydrological connections that allow lubricating seasonal meltwater to reach the base of the Greenland Ice Sheet. Here we use new surface velocity observations to examine the influence of supraglacial lake drainages and surface melt rate on ice flow. We find large, spatially extensive speedups concurrent with times of lake drainage, showing that lakes play a key role in modulating regional ice flow. While surface meltwater is supplied to the bed via a geographically sparse network of moulins, the observed ice-flow enhancement suggests that this meltwater spreads widely over the ice-sheet bed. We also find that the complex spatial pattern of speedup is strongly determined by the combined influence of bed and surface topography on subglacial water flow. Thus, modeling of ice-sheet basal hydrology likely will require knowledge of bed topography resolved at scales (sub-kilometer) far finer than existing data (several km).
    Description: This work was supported jointly by National Science Foundation’s Office of Polar Programs (NSF-OPP) and National Aeronautics and Space Administration’s (NASA) Cryospheric Sciences Program (and through ARC-0520382, ARC-1023382 and NNX10AI33G to I. Joughin; and ARC-0520077, ARC-1023364 and NNX10AI30G to S. B. Das and M. D. Behn). The Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Research Chairs Program (CRC) provided support for G. E. Flowers. Support for R. B. Alley was provided by NSF (ANT-0424589 and ARC- 0909335). Contributions by M. A. King were supported by NERC and an Australian Research Council Future Fellowship (project number FT110100207).
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 10
    facet.materialart.
    Unknown
    Satellite-based estimates of Antarctic surface meltwater fluxes (2014)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 40 (2013): 6148–6153, doi:10.1002/2013GL058138.
    Description: This study generates novel satellite-derived estimates of Antarctic-wide annual (1999–2009) surface meltwater production using an empirical relationship between radar backscatter from the QuikSCAT (QSCAT) satellite and melt calculated from in situ energy balance observations. The resulting QSCAT-derived melt fluxes significantly agree with output from the regional climate model RACMO2.1 and with independent ground-based observations. The high-resolution (4.45 km) QSCAT-based melt fluxes uniquely detect interannually persistent and intense melt (〉400 mm water equivalent (w.e.) year−1) on interior Larsen C Ice Shelf that is not simulated by RACMO2.1. This supports a growing understanding of the importance of a föhn effect in this region and quantifies the resulting locally enhanced melting that is spatially consistent with recently observed Larsen C thinning. These new results highlight important cryosphere-climate interactions and processes that are presently not fully captured by the coarser-resolution (27 km) regional climate model.
    Description: This research was supported by NASA Headquarters under the NASA Earth and Space Science Fellowship Program (grant NNX12AO01H), the NASA Cryospheric Sciences Program (grant NNX10AP09G), and the NSF Antarctic Sciences Section (grant ANT-063203).
    Description: 2014-06-04
    Keywords: Antarctica ; Surface melt ; Ice shelves ; Remote sensing
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: text/plain
    Format: application/pdf
    Format: application/postscript
    Format: application/msword
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...