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Record Details

Record 69 of 4628
Antarctic Firn Compaction Rates from Repeat-Track Airborne Radar Data: I. Methods
External Online Source: doi:10.3189/2015AoG70A203
Author and Affiliation:
Medley, B.(NASA Goddard Space Flight Center, Greenbelt, MD United States)
Ligtenberg, S. R. M.(Utrecht Univ., Utrecht, Netherlands)
Joughin, I.(Washington Univ., Seattle, WA, United States)
Van Den Broeke, M. R.(Utrecht Univ., Utrecht, Netherlands)
Gogineni, S.(Kansas Univ., Lawrence, KS, United States)
Nowicki, S.(NASA Goddard Space Flight Center, Greenbelt, MD United States)
Abstract: While measurements of ice-sheet surface elevation change are increasingly used to assess mass change, the processes that control the elevation fluctuations not related to ice-flow dynamics (e.g. firn compaction and accumulation) remain difficult to measure. Here we use radar data from the Thwaites Glacier (West Antarctica) catchment to measure the rate of thickness change between horizons of constant age over different time intervals: 2009-10, 2010-11 and 2009-11. The average compaction rate to approximately 25m depth is 0.33ma(exp -1), with largest compaction rates near the surface. Our measurements indicate that the accumulation rate controls much of the spatio-temporal variations in the compaction rate while the role of temperature is unclear due to a lack of measurements. Based on a semi-empirical, steady-state densification model, we find that surveying older firn horizons minimizes the potential bias resulting from the variable depth of the constant age horizon. Our results suggest that the spatiotemporal variations in the firn compaction rate are an important consideration when converting surface elevation change to ice mass change. Compaction rates varied by up to 0.12ma(exp -1) over distances less than 6km and were on average greater than 20% larger during the 2010-11 interval than during 2009-10.
Publication Date: Oct 01, 2015
Document ID:
20160005218
(Acquired Apr 20, 2016)
Subject Category: EARTH RESOURCES AND REMOTE SENSING
Report/Patent Number: GSFC-E-DAA-TN31432
Document Type: Journal Article
Publication Information: Annals of Glaciology; Volume 56; No. 70; 155-166
Publisher Information: International Glaciological Society (IGS)
Contract/Grant/Task Num: NNG10HP19C; NNX09AR77G; NNX10AT68G; NSF-ANT-0631973; NSF-ANT-0424589
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD United States
Description: 12p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: ANTARCTIC REGIONS; ICE; ELEVATION; THICKNESS; STEADY STATE; AIRBORNE RADAR; RADIO ALTIMETERS; RADAR DATA; SNOW COVER; SPATIAL DISTRIBUTION; TEMPORAL DISTRIBUTION; DENSITY MEASUREMENT; VARIABILITY
Other Descriptors: ACCUMULATION; GROUND-PENETRATING RADAR; POLAR FIRN
Availability Source: Other Sources
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