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Dark zone of the Greenland Ice Sheet controlled by distributed biologically-active impurities.

https://arctichealth.org/en/permalink/ahliterature291280
Source
Nat Commun. 2018 03 14; 9(1):1065
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
03-14-2018
Author
Jonathan C Ryan
Alun Hubbard
Marek Stibal
Tristram D Irvine-Fynn
Joseph Cook
Laurence C Smith
Karen Cameron
Jason Box
Author Affiliation
Centre for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, UK.
Source
Nat Commun. 2018 03 14; 9(1):1065
Date
03-14-2018
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Keywords
Environmental monitoring
Greenland
Ice Cover
Abstract
Albedo-a primary control on surface melt-varies considerably across the Greenland Ice Sheet yet the specific surface types that comprise its dark zone remain unquantified. Here we use UAV imagery to attribute seven distinct surface types to observed albedo along a 25?km transect dissecting the western, ablating sector of the ice sheet. Our results demonstrate that distributed surface impurities-an admixture of dust, black carbon and pigmented algae-explain 73% of the observed spatial variability in albedo and are responsible for the dark zone itself. Crevassing and supraglacial water also drive albedo reduction but due to their limited extent, explain just 12 and 15% of the observed variability respectively. Cryoconite, concentrated in large holes or fluvial deposits, is the darkest surface type but accounts for
Notes
Cites: IEEE Trans Pattern Anal Mach Intell. 1986 Jun;8(6):679-98 PMID 21869365
Cites: Proc Natl Acad Sci U S A. 2015 Jan 27;112(4):1001-6 PMID 25583477
Cites: Front Microbiol. 2015 Mar 24;6:225 PMID 25852678
Cites: Proc Natl Acad Sci U S A. 2014 Jun 3;111(22):7964-7 PMID 24843158
Cites: Nature. 2013 Jun 6;498(7452):51-9 PMID 23739423
Cites: FEMS Microbiol Ecol. 2012 Mar;79(3):638-48 PMID 22092588
Cites: Science. 2008 Jul 4;321(5885):111-3 PMID 18599784
Cites: Nat Commun. 2016 Jun 22;7:11968 PMID 27329445
Cites: ISME J. 2012 Dec;6(12):2302-13 PMID 23018772
PubMed ID
29540720 View in PubMed
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Source
Sci Am. 2007 Apr;296(4):16, 19
Publication Type
Article
Date
Apr-2007
Author
Biello David
Source
Sci Am. 2007 Apr;296(4):16, 19
Date
Apr-2007
Language
English
Publication Type
Article
Keywords
Climate
Greenhouse Effect
Greenland
Ice Cover
PubMed ID
17479619 View in PubMed
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High-Resolution in Situ Measurement of Nitrate in Runoff from the Greenland Ice Sheet.

https://arctichealth.org/en/permalink/ahliterature292354
Source
Environ Sci Technol. 2017 Nov 07; 51(21):12518-12527
Publication Type
Journal Article
Date
Nov-07-2017
Author
Alexander D Beaton
Jemma L Wadham
Jon Hawkings
Elizabeth A Bagshaw
Guillaume Lamarche-Gagnon
Matthew C Mowlem
Martyn Tranter
Author Affiliation
National Oceanography Centre , European Way, Southampton, SO14 3ZH, U.K.
Source
Environ Sci Technol. 2017 Nov 07; 51(21):12518-12527
Date
Nov-07-2017
Language
English
Publication Type
Journal Article
Keywords
Greenland
Ice Cover
Nitrates
Rivers
Seasons
Abstract
We report the first in situ high-resolution nitrate time series from two proglacial meltwater rivers draining the Greenland Ice Sheet, using a recently developed submersible analyzer based on lab-on-chip (LOC) technology. The low sample volume (320 µL) required by the LOC analyzer meant that low concentration (few micromolar to submicromolar), highly turbid subglacial meltwater could be filtered and colorimetrically analyzed in situ. Nitrate concentrations in rivers draining Leverett Glacier in southwest Greenland and Kiattuut Sermiat in southern Greenland exhibited a clear diurnal signal and a gradual decline at the commencement of the melt season, displaying trends that would not be discernible using traditional daily manual sampling. Nitrate concentrations varied by 4.4 µM (±0.2 µM) over a 10 day period at Kiattuut Sermiat and 3.0 µM (±0.2 µM) over a 14 day period at Leverett Glacier. Marked changes in nitrate concentrations were observed when discharge began to increase. High-resolution in situ measurements such as these have the potential to significantly advance the understanding of nutrient cycling in remote systems, where the dynamics of nutrient release are complex but are important for downstream biogeochemical cycles.
PubMed ID
28954516 View in PubMed
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Climate change: Rethinking the sea-ice tipping point

https://arctichealth.org/en/permalink/ahliterature276019
Source
Nature. 2011 Mar 3;471(7336):47-48
Publication Type
Article
Date
Mar-3-2011
Author
Serreze, MC
Source
Nature. 2011 Mar 3;471(7336):47-48
Date
Mar-3-2011
Language
English
Publication Type
Article
Keywords
Climate change
Ice Cover
Sea ice
Abstract
Summer sea-ice extent in the Arctic has decreased greatly during recent decades. Simulations of twenty-first-century climate suggest that the ice can recover from artificially imposed ice-free summer conditions within a couple of years.
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Present and past dynamics of Inughuit resource spaces.

https://arctichealth.org/en/permalink/ahliterature295697
Source
Ambio. 2018 Apr; 47(Suppl 2):244-264
Publication Type
Journal Article
Date
Apr-2018
Author
Janne Flora
Kasper Lambert Johansen
Bjarne Grønnow
Astrid Oberborbeck Andersen
Anders Mosbech
Author Affiliation
Department of Anthropology, University of Copenhagen, Øster Farimagsgade 5, 1353, Copenhagen K, Denmark. jakf@bios.au.dk.
Source
Ambio. 2018 Apr; 47(Suppl 2):244-264
Date
Apr-2018
Language
English
Publication Type
Journal Article
Keywords
Animals
Greenland
Humans
Ice Cover
Weather
Abstract
Information from a collaborative GPS tracking project, Piniariarneq, involving 17 occupational hunters from Qaanaaq and Savissivik, Northwest Greenland, is used to explore the resource spaces of hunters in Avanersuaq today. By comparison with historical records from the time of the Thule Trading Station and the decades following its closure, we reveal a marked variability in resource spaces over time. It is argued that the dynamics of resources and resource spaces in Thule are not underlain by animal distribution and migration patterns, or changes in weather and sea ice conditions alone; but also by economic opportunities, human mobility, settlement patterns, particular historical events and trajectories, and not least by economic and political interests developed outside the region.
Notes
Cites: Ambio. 2018 Apr;47(Suppl 2):226-243 PMID 29516440
PubMed ID
29520751 View in PubMed
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A foundation of ecology rediscovered: 100 years of succession on the William S. Cooper plots in Glacier Bay, Alaska.

https://arctichealth.org/en/permalink/ahliterature295926
Source
Ecology. 2017 Jun; 98(6):1513-1523
Publication Type
Journal Article
Date
Jun-2017
Author
Brian Buma
Sarah Bisbing
John Krapek
Glenn Wright
Author Affiliation
Department of Natural Sciences, School of Arts and Sciences, University of Alaska, Southeast, 11120 Glacier Highway, Juneau, Alaska, 99801, USA.
Source
Ecology. 2017 Jun; 98(6):1513-1523
Date
Jun-2017
Language
English
Publication Type
Journal Article
Keywords
Alaska
Bays
Ecology
Ice Cover
Soil
Abstract
Understanding plant community succession is one of the original pursuits of ecology, forming some of the earliest theoretical frameworks in the field. Much of this was built on the long-term research of William S. Cooper, who established a permanent plot network in Glacier Bay, Alaska, in 1916. This study now represents the longest-running primary succession plot network in the world. Permanent plots are useful for their ability to follow mechanistic change through time without assumptions inherent in space-for-time (chronosequence) designs. After 100-yr, these plots show surprising variety in species composition, soil characteristics (carbon, nitrogen, depth), and percent cover, attributable to variation in initial vegetation establishment first noted by Cooper in the 1916-1923 time period, partially driven by dispersal limitations. There has been almost a complete community composition replacement over the century and general species richness increase, but the effective number of species has declined significantly due to dominance of Salix species which established 100-yr prior (the only remaining species from the original cohort). Where Salix dominates, there is no establishment of "later" successional species like Picea. Plots nearer the entrance to Glacier Bay, and thus closer to potential seed sources after the most recent glaciation, have had consistently higher species richness for 100 yr. Age of plots is the best predictor of soil N content and C:N ratio, though plots still dominated by Salix had lower overall N; soil accumulation was more associated with dominant species. This highlights the importance of contingency and dispersal in community development. The 100-yr record of these plots, including species composition, spatial relationships, cover, and observed interactions between species provides a powerful view of long-term primary succession.
PubMed ID
28558159 View in PubMed
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Climate science: The history of Greenland's ice.

https://arctichealth.org/en/permalink/ahliterature280937
Source
Nature. 2016 12 07;540(7632):202-203
Publication Type
Article
Date
12-07-2016
Author
Pierre-Henri Blard
Guillaume Leduc
Neil Glasser
Source
Nature. 2016 12 07;540(7632):202-203
Date
12-07-2016
Language
English
Publication Type
Article
Keywords
Climate
Greenland
Ice
Ice Cover
Science
Notes
Comment On: Nature. 2016 Dec 7;540(7632):252-25527929018
Comment On: Nature. 2016 Dec 7;540(7632):256-26027929005
Cites: Science. 2015 Jul 10;349(6244):aaa401926160951
Cites: Nature. 2016 Dec 7;540(7632):256-26027929005
Cites: Nature. 2016 Dec 7;540(7632):252-25527929018
PubMed ID
27929019 View in PubMed
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Environmental predictors of ice seal presence in the Bering Sea.

https://arctichealth.org/en/permalink/ahliterature269641
Source
PLoS One. 2014;9(9):e106998
Publication Type
Article
Date
2014
Author
Jennifer L Miksis-Olds
Laura E Madden
Source
PLoS One. 2014;9(9):e106998
Date
2014
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Ice Cover
Seals, Earless
Abstract
Ice seals overwintering in the Bering Sea are challenged with foraging, finding mates, and maintaining breathing holes in a dark and ice covered environment. Due to the difficulty of studying these species in their natural environment, very little is known about how the seals navigate under ice. Here we identify specific environmental parameters, including components of the ambient background sound, that are predictive of ice seal presence in the Bering Sea. Multi-year mooring deployments provided synoptic time series of acoustic and oceanographic parameters from which environmental parameters predictive of species presence were identified through a series of mixed models. Ice cover and 10 kHz sound level were significant predictors of seal presence, with 40 kHz sound and prey presence (combined with ice cover) as potential predictors as well. Ice seal presence showed a strong positive correlation with ice cover and a negative association with 10 kHz environmental sound. On average, there was a 20-30 dB difference between sound levels during solid ice conditions compared to open water or melting conditions, providing a salient acoustic gradient between open water and solid ice conditions by which ice seals could orient. By constantly assessing the acoustic environment associated with the seasonal ice movement in the Bering Sea, it is possible that ice seals could utilize aspects of the soundscape to gauge their safe distance to open water or the ice edge by orienting in the direction of higher sound levels indicative of open water, especially in the frequency range above 1 kHz. In rapidly changing Arctic and sub-Arctic environments, the seasonal ice conditions and soundscapes are likely to change which may impact the ability of animals using ice presence and cues to successfully function during the winter breeding season.
Notes
Cites: Can J Zool. 1975 Mar;53(3):227-311125867
Cites: Science. 2005 Apr 8;308(5719):22115821083
Cites: Science. 2006 Sep 22;313(5794):1768-7016990545
Cites: J Acoust Soc Am. 2008 Apr;123(4):1952-6218397003
Cites: PLoS One. 2008;3(12):e406519115006
Cites: J Exp Biol. 2014 Mar 1;217(Pt 5):726-3424574387
Cites: PLoS One. 2011;6(12):e2857222163314
Cites: Proc Biol Sci. 2012 Sep 7;279(1742):3622-3122673354
Cites: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2013 Jun;199(6):491-50723563644
Cites: Physiology (Bethesda). 2013 Sep;28(5):276-8323997187
Cites: PLoS One. 2013;8(10):e7933724205381
Cites: J Acoust Soc Am. 2010 Sep;128(3):EL144-920815431
PubMed ID
25229453 View in PubMed
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Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987.

https://arctichealth.org/en/permalink/ahliterature276504
Source
Sci Data. 2016;3:160032
Publication Type
Article
Date
2016
Author
Niels J Korsgaard
Christopher Nuth
Shfaqat A Khan
Kristian K Kjeldsen
Anders A Bjørk
Anders Schomacker
Kurt H Kjær
Source
Sci Data. 2016;3:160032
Date
2016
Language
English
Publication Type
Article
Keywords
Greenland
Ice Cover
Models, Theoretical
Reproducibility of Results
Abstract
Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978-1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25?m gridded DEM and a 2?m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10?m horizontally and 6?m vertically while the precision is better than 4?m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps.
Notes
Comment On: Science. 2012 Aug 3;337(6094):569-7322859486
Comment On: Nature. 2015 Dec 17;528(7582):396-40026672555
PubMed ID
27164457 View in PubMed
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The Dynamics of Greenland's Glacial Fjords and Their Role in Climate.

https://arctichealth.org/en/permalink/ahliterature274749
Source
Ann Rev Mar Sci. 2015;7:89-112
Publication Type
Article
Date
2015
Author
Fiamma Straneo
Claudia Cenedese
Source
Ann Rev Mar Sci. 2015;7:89-112
Date
2015
Language
English
Publication Type
Article
Keywords
Climate change
Environmental Monitoring - methods
Estuaries
Greenland
Ice Cover
Abstract
Rapid mass loss from the Greenland Ice Sheet has sparked interest in its glacial fjords for two main reasons: Increased submarine melting of glaciers terminating in fjords is a plausible trigger for glacier retreat, and the anomalous freshwater discharged from Greenland is transformed by fjord processes before being released into the large-scale ocean. Knowledge of the fjords' dynamics is thus key to understanding ice sheet variability and its impact on climate. Although Greenland's fjords share some commonalities with other fjords, their deep sills and deeply grounded glaciers, the presence of Atlantic and Polar Waters on the continental shelves outside the fjords' mouths, and the seasonal discharge at depth of large amounts of surface melt make them unique systems that do not fit existing paradigms. Major gaps in understanding include the interaction of the buoyancy-driven circulation (forced by the glacier) and shelf-driven circulation, and the dynamics in the near-ice zone. These must be addressed before appropriate forcing conditions can be supplied to ice sheet and ocean/climate models.
PubMed ID
25149564 View in PubMed
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248 records – page 1 of 25.