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Ultee L, Felikson D, Minchew B, Stearns LA, Riel B. Helheim Glacier ice velocity variability responds to runoff and terminus position change at different timescales. Nat Commun 2022; 13:6022. [PMID: 36224175 PMCID: PMC9556534 DOI: 10.1038/s41467-022-33292-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 09/12/2022] [Indexed: 11/09/2022] Open
Abstract
The Greenland Ice Sheet discharges ice to the ocean through hundreds of outlet glaciers. Recent acceleration of Greenland outlet glaciers has been linked to both oceanic and atmospheric drivers. Here, we leverage temporally dense observations, regional climate model output, and newly developed time series analysis tools to assess the most important forcings causing ice flow variability at one of the largest Greenland outlet glaciers, Helheim Glacier, from 2009 to 2017. We find that ice speed correlates most strongly with catchment-integrated runoff at seasonal to interannual scales, while multi-annual flow variability correlates most strongly with multi-annual terminus variability. The disparate time scales and the influence of subglacial topography on Helheim Glacier’s dynamics highlight different regimes that can inform modeling and forecasting of its future. Notably, our results suggest that the recent terminus history observed at Helheim is a response to, rather than the cause of, upstream changes. Factors driving ice flow variability in Greenland vary by timescale. At seasonal scale, Helheim Glacier ice velocity responds most strongly to meltwater runoff. Glacier terminus position drives velocity variability at longer time scales.
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Affiliation(s)
- Lizz Ultee
- Dept. of Earth & Climate Sciences, Middlebury College, Middlebury, VT, USA. .,School of Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA. .,Dept. of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Denis Felikson
- Cryospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Goddard Earth Sciences Technology and Research II, Morgan State University, Baltimore, MD, USA
| | - Brent Minchew
- Dept. of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Leigh A Stearns
- Department of Geology, University of Kansas, Lawrence, KS, USA
| | - Bryan Riel
- Dept. of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.,School of Earth Sciences, Zhejiang University, 310027, Hangzhou, China
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Millan R, Rignot E, Mouginot J, Wood M, Bjørk AA, Morlighem M. Vulnerability of Southeast Greenland Glaciers to Warm Atlantic Water From Operation IceBridge and Ocean Melting Greenland Data. GEOPHYSICAL RESEARCH LETTERS 2018; 45:2688-2696. [PMID: 29937604 PMCID: PMC5993238 DOI: 10.1002/2017gl076561] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/14/2018] [Accepted: 02/18/2018] [Indexed: 05/02/2023]
Abstract
We employ National Aeronautics and Space Administration (NASA)'s Operation IceBridge high-resolution airborne gravity from 2016, NASA's Ocean Melting Greenland bathymetry from 2015, ice thickness from Operation IceBridge from 2010 to 2015, and BedMachine v3 to analyze 20 major southeast Greenland glaciers. The results reveal glacial fjords several hundreds of meters deeper than previously thought; the full extent of the marine-based portions of the glaciers; deep troughs enabling warm, salty Atlantic Water (AW) to reach the glacier fronts and melt them from below; and few shallow sills that limit the access of AW. The new oceanographic and topographic data help to fully resolve the complex pattern of historical ice front positions from the 1930s to 2017: glaciers exposed to AW and resting on retrograde beds have retreated rapidly, while glaciers perched on shallow sills or standing in colder waters or with major sills in the fjords have remained stable.
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Affiliation(s)
- R. Millan
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
| | - E. Rignot
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
- Jet Propulsion LaboratoryCaltechPasadenaCAUSA
| | - J. Mouginot
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
| | - M. Wood
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
| | - A. A. Bjørk
- Centre for GeoGenetics, Natural History Museum of DenmarkUniversity of CopenhagenCopenhagenDenmark
| | - M. Morlighem
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
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Khan SA, Aschwanden A, Bjørk AA, Wahr J, Kjeldsen KK, Kjær KH. Greenland ice sheet mass balance: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:046801. [PMID: 25811969 DOI: 10.1088/0034-4885/78/4/046801] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Over the past quarter of a century the Arctic has warmed more than any other region on Earth, causing a profound impact on the Greenland ice sheet (GrIS) and its contribution to the rise in global sea level. The loss of ice can be partitioned into processes related to surface mass balance and to ice discharge, which are forced by internal or external (atmospheric/oceanic/basal) fluctuations. Regardless of the measurement method, observations over the last two decades show an increase in ice loss rate, associated with speeding up of glaciers and enhanced melting. However, both ice discharge and melt-induced mass losses exhibit rapid short-term fluctuations that, when extrapolated into the future, could yield erroneous long-term trends. In this paper we review the GrIS mass loss over more than a century by combining satellite altimetry, airborne altimetry, interferometry, aerial photographs and gravimetry data sets together with modelling studies. We revisit the mass loss of different sectors and show that they manifest quite different sensitivities to atmospheric and oceanic forcing. In addition, we discuss recent progress in constructing coupled ice-ocean-atmosphere models required to project realistic future sea-level changes.
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Affiliation(s)
- Shfaqat A Khan
- DTU Space-National Space Institute, Technical University of Denmark, Department of Geodesy, Kgs. Lyngby, Denmark
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Veitch SA, Nettles M. Spatial and temporal variations in Greenland glacial-earthquake activity, 1993-2010. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012jf002412] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Humphrey NF, Harper JT, Pfeffer WT. Thermal tracking of meltwater retention in Greenland's accumulation area. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jf002083] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Seale A, Christoffersen P, Mugford RI, O'Leary M. Ocean forcing of the Greenland Ice Sheet: Calving fronts and patterns of retreat identified by automatic satellite monitoring of eastern outlet glaciers. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jf001847] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Khan SA, Liu L, Wahr J, Howat I, Joughin I, van Dam T, Fleming K. GPS measurements of crustal uplift near Jakobshavn Isbræ due to glacial ice mass loss. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jb007490] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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van den Broeke M, Bamber J, Ettema J, Rignot E, Schrama E, van de Berg WJ, van Meijgaard E, Velicogna I, Wouters B. Partitioning recent Greenland mass loss. Science 2010; 326:984-6. [PMID: 19965509 DOI: 10.1126/science.1178176] [Citation(s) in RCA: 693] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mass budget calculations, validated with satellite gravity observations [from the Gravity Recovery and Climate Experiment (GRACE) satellites], enable us to quantify the individual components of recent Greenland mass loss. The total 2000-2008 mass loss of approximately 1500 gigatons, equivalent to 0.46 millimeters per year of global sea level rise, is equally split between surface processes (runoff and precipitation) and ice dynamics. Without the moderating effects of increased snowfall and refreezing, post-1996 Greenland ice sheet mass losses would have been 100% higher. Since 2006, high summer melt rates have increased Greenland ice sheet mass loss to 273 gigatons per year (0.75 millimeters per year of equivalent sea level rise). The seasonal cycle in surface mass balance fully accounts for detrended GRACE mass variations, confirming insignificant subannual variation in ice sheet discharge.
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Farrell SL, Laxon SW, McAdoo DC, Yi D, Zwally HJ. Five years of Arctic sea ice freeboard measurements from the Ice, Cloud and land Elevation Satellite. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jc005074] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Joughin I, Howat IM, Fahnestock M, Smith B, Krabill W, Alley RB, Stern H, Truffer M. Continued evolution of Jakobshavn Isbrae following its rapid speedup. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008jf001023] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Ohmura A. Cryosphere during the twentieth century. GEOPHYSICAL MONOGRAPH SERIES 2004. [DOI: 10.1029/150gm19] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Affiliation(s)
- Paul R Epstein
- Center for Health and the Global Environment, Harvard Medical School, 333 Longwood Avenue, Boston, MA 02215, USA.
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Davis CH, McConnell JR, Bolzan J, Bamber JL, Thomas RH, Mosley-Thompson E. Elevation change of the southern Greenland ice sheet from 1978 to 1988: Interpretation. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900167] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Mosley-Thompson E, McConnell JR, Bales RC, Li Z, Lin PN, Steffen K, Thompson LG, Edwards R, Bathke D. Local to regional-scale variability of annual net accumulation on the Greenland ice sheet from PARCA cores. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900067] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Rignot E, Gogineni S, Joughin I, Krabill W. Contribution to the glaciology of northern Greenland from satellite radar interferometry. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900071] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bromwich DH, Chen QS, Bai LS, Cassano EN, Li Y. Modeled precipitation variability over the Greenland Ice Sheet. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900251] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wahr J, van Dam T, Larson K, Francis O. GPS measurements of vertical crustal motion in Greenland. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900154] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Thomas RH. Program for Arctic Regional Climate Assessment (PARCA): Goals, key findings, and future directions. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900042] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abdalati W, Krabill W, Frederick E, Manizade S, Martin C, Sonntag J, Swift R, Thomas R, Wright W, Yungel J. Outlet glacier and margin elevation changes: Near-coastal thinning of the Greenland ice sheet. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900192] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Thomas R, Csatho B, Davis C, Kim C, Krabill W, Manizade S, McConnell J, Sonntag J. Mass balance of higher-elevation parts of the Greenland ice sheet. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900033] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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McConnell JR, Lamorey G, Hanna E, Mosley-Thompson E, Bales RC, Belle-Oudry D, Kyne JD. Annual net snow accumulation over southern Greenland from 1975 to 1998. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900129] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wahr J, van Dam T, Larson K, Francis O. Geodetic measurements in Greenland and their implications. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jb000211] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
The ranges of infectious diseases and vectors are changing in altitude, along with shifts in plant communities and the retreat of alpine glaciers. Additionally, extreme weather events create conditions conducive to clusters of insect-, rodent- and water-borne diseases. Accelerating climate change carries profound threats for public health and society.
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Affiliation(s)
- P R Epstein
- Center for Health and the Global Environment, Harvard Medical School, 260 Longwood Avenue, Boston, MA 02115, USA.
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Changes in Greenland ice sheet elevation attributed primarily to snow accumulation variability. Nature 2000; 406:877-9. [PMID: 10972286 DOI: 10.1038/35022555] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The response of grounded ice sheets to a changing climate critically influences possible future changes in sea level. Recent satellite surveys over southern Greenland show little overall elevation change at higher elevations, but large spatial variability. Using satellite studies alone, it is not possible to determine the geophysical processes responsible for the observed elevation changes and to decide if recent rates of change exceed the natural variability. Here we derive changes in ice-sheet elevation in southern Greenland, for the years 1978-88, using a physically based model of firn densification and records of annual snow accumulation reconstructed from 12 ice cores at high elevation. Our patterns of accumulation-driven elevation change agree closely with contemporaneous satellite measurements of ice-sheet elevation change, and we therefore attribute the changes observed in 1978-88 to variability in snow accumulation. Similar analyses of longer ice-core records show that in this decade the Greenland ice sheet exhibited typical variability at high elevations, well within the long-term natural variability. Our results indicate that a better understanding of ice-sheet mass changes will require long-term measurements of both surface elevation and snow accumulation.
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Thomas R, Akins T, Csatho B, Fahnestock M, Gogineni P, Kim C, Sonntag J. Mass Balance of the Greenland Ice Sheet at High Elevations. Science 2000; 289:426-428. [PMID: 10903197 DOI: 10.1126/science.289.5478.426] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Comparison of ice discharge from higher elevation areas of the entire Greenland Ice Sheet with total snow accumulation gives estimates of ice thickening rates over the past few decades. On average, the region has been in balance, but with thickening of 21 centimeters per year in the southwest and thinning of 30 centimeters per year in the southeast. The north of the ice sheet shows less variability, with average thickening of 2 centimeters per year in the northeast and thinning of about 5 centimeters per year in the northwest. These results agree well with those from repeated altimeter surveys, except in the extreme south, where we find substantially higher rates of both thickening and thinning.
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Affiliation(s)
- R Thomas
- EG&G Services, Wallops Flight Facility, Building N-159, Wallops Island, VA 23337, USA. Jet Propulsion Laboratory, M/S 300-325, 4800 Oak Grove Drive, Pasadena, CA 91109, USA. Byrd Polar Research Center, Ohio State University, Columbus, OH 42310, USA. ESSIC, University of Maryland, College Park, MD 20742, USA. Radar Systems and Remote Sensing Laboratory, University of Kansas, Lawrence, KS 66045, USA
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Krabill W, Abdalati W, Frederick E, Manizade S, Martin C, Sonntag J, Swift R, Thomas R, Wright W, Yungel J. Greenland Ice Sheet: High-Elevation Balance and Peripheral Thinning. Science 2000; 289:428-430. [PMID: 10903198 DOI: 10.1126/science.289.5478.428] [Citation(s) in RCA: 331] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Aircraft laser-altimeter surveys over northern Greenland in 1994 and 1999 have been coupled with previously reported data from southern Greenland to analyze the recent mass-balance of the Greenland Ice Sheet. Above 2000 meters elevation, the ice sheet is in balance on average but has some regions of local thickening or thinning. Thinning predominates at lower elevations, with rates exceeding 1 meter per year close to the coast. Interpolation of our results between flight lines indicates a net loss of about 51 cubic kilometers of ice per year from the entire ice sheet, sufficient to raise sea level by 0.13 millimeter per year-approximately 7% of the observed rise.
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Affiliation(s)
- W Krabill
- Laboratory for Hydrospheric Processes, NASA Goddard Space Flight Center and EG&G Services, Wallops Flight Facility, Building N-159, Wallops Island, VA 23337, USA. Laboratory for Hydrospheric Processes, NASA Goddard Space Flight Center, Building 33, Room A225, Greenbelt, MD 20771, USA
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Hamilton GS, Whillans IM. Point measurements of mass balance of the Greenland Ice Sheet using precision vertical Global Positioning System (GPS) surveys. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jb900102] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Braaten DA. Direct measurements of episodic snow accumulation on the Antarctic polar plateau. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jd900099] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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McConnell JR, Mosley-Thompson E, Bromwich DH, Bales RC, Kyne JD. Interannual variations of snow accumulation on the Greenland Ice Sheet (1985-1996): new observations versus model predictions. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999jd901049] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Affiliation(s)
- P R Epstein
- Center for Health and the Global Environment, Harvard Medical School, Boston, MA 02115, USA.
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