Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009
Published mass balance estimates for the Antarctic Ice Sheet (AIS) lie between approximately +50 to -250 Gt/year for 1992 to 2009, which span a range equivalent to 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar-altimeter measurements of elevation ch...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20120002070 2023-05-15T13:43:16+02:00 Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009 Zwally, H. Jay Giovinetto, Mario B. Unclassified, Unlimited, Publicly available December 05, 2011 application/pdf http://hdl.handle.net/2060/20120002070 unknown Document ID: 20120002070 http://hdl.handle.net/2060/20120002070 Copyright, Distribution as joint owner in the copyright CASI Geophysics GSFC.CP.5737.2011 American Geophysial Union (AGU) 2011 Fall Meeting; 5-9 Dec. 2011; San Francisco, CA; United States 2011 ftnasantrs 2019-07-21T00:54:41Z Published mass balance estimates for the Antarctic Ice Sheet (AIS) lie between approximately +50 to -250 Gt/year for 1992 to 2009, which span a range equivalent to 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar-altimeter measurements of elevation change by European Remote-sensing Satellites (ERS) (+28 and -31 Gt/year) lie in the upper part, whereas estimates from the Input-minus-Output Method (IOM) and the Gravity Recovery and Climate Experiment (GRACE) lie in the lower part (-40 to -246 Gt/year). We compare the various estimates, discuss the methodology used, and critically assess the results. Although recent reports of large and accelerating rates of mass loss from GRACE=based studies cite agreement with IOM results, our evaluation does not support that conclusion. We find that the extrapolation used in the published IOM estimates for the 15 % of the periphery for which discharge velocities are not observed gives twice the rate of discharge per unit of associated ice-sheet area than the 85% faster-moving parts. Our calculations show that the published extrapolation overestimates the ice discharge by 282 Gt/yr compared to our assumption that the slower moving areas have 70% as much discharge per area as the faster moving parts. Also, published data on the time-series of discharge velocities and accumulation/precipitation do not support mass output increases or input decreases with time, respectively. Our modified IOM estimate, using the 70% discharge assumption and substituting input from a field-data compilation for input from an atmospheric model over 6% of area, gives a loss of only 13 Gt/year (versus 136 Gt/year) for the period around 2000. Two ERS-based estimates, our modified IOM, and a GRACE-based estimate for observations within 1992 to 2005 lie in a narrowed range of +27 to - 40 Gt/year, which is about 3% of the annual mass input and only 0.2 mm/year SLE. Our preferred estimate for 1992-2001 is - 47 Gt/year for West Antarctica, + 16 Gt/year for East Antarctica, and -31 Gt/year overall (+0.1 mm/year SLE), not including part of the Antarctic Peninsula (1.07 % of the AIS area) Other/Unknown Material Antarc* Antarctic Antarctic Peninsula Antarctica East Antarctica Ice Sheet West Antarctica NASA Technical Reports Server (NTRS) Antarctic The Antarctic Antarctic Peninsula East Antarctica West Antarctica |
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NASA Technical Reports Server (NTRS) |
op_collection_id |
ftnasantrs |
language |
unknown |
topic |
Geophysics |
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Geophysics Zwally, H. Jay Giovinetto, Mario B. Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009 |
topic_facet |
Geophysics |
description |
Published mass balance estimates for the Antarctic Ice Sheet (AIS) lie between approximately +50 to -250 Gt/year for 1992 to 2009, which span a range equivalent to 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar-altimeter measurements of elevation change by European Remote-sensing Satellites (ERS) (+28 and -31 Gt/year) lie in the upper part, whereas estimates from the Input-minus-Output Method (IOM) and the Gravity Recovery and Climate Experiment (GRACE) lie in the lower part (-40 to -246 Gt/year). We compare the various estimates, discuss the methodology used, and critically assess the results. Although recent reports of large and accelerating rates of mass loss from GRACE=based studies cite agreement with IOM results, our evaluation does not support that conclusion. We find that the extrapolation used in the published IOM estimates for the 15 % of the periphery for which discharge velocities are not observed gives twice the rate of discharge per unit of associated ice-sheet area than the 85% faster-moving parts. Our calculations show that the published extrapolation overestimates the ice discharge by 282 Gt/yr compared to our assumption that the slower moving areas have 70% as much discharge per area as the faster moving parts. Also, published data on the time-series of discharge velocities and accumulation/precipitation do not support mass output increases or input decreases with time, respectively. Our modified IOM estimate, using the 70% discharge assumption and substituting input from a field-data compilation for input from an atmospheric model over 6% of area, gives a loss of only 13 Gt/year (versus 136 Gt/year) for the period around 2000. Two ERS-based estimates, our modified IOM, and a GRACE-based estimate for observations within 1992 to 2005 lie in a narrowed range of +27 to - 40 Gt/year, which is about 3% of the annual mass input and only 0.2 mm/year SLE. Our preferred estimate for 1992-2001 is - 47 Gt/year for West Antarctica, + 16 Gt/year for East Antarctica, and -31 Gt/year overall (+0.1 mm/year SLE), not including part of the Antarctic Peninsula (1.07 % of the AIS area) |
format |
Other/Unknown Material |
author |
Zwally, H. Jay Giovinetto, Mario B. |
author_facet |
Zwally, H. Jay Giovinetto, Mario B. |
author_sort |
Zwally, H. Jay |
title |
Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009 |
title_short |
Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009 |
title_full |
Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009 |
title_fullStr |
Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009 |
title_full_unstemmed |
Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992 - 2009 |
title_sort |
assessment of antarctic ice-sheet mass balance estimates: 1992 - 2009 |
publishDate |
2011 |
url |
http://hdl.handle.net/2060/20120002070 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Antarctic The Antarctic Antarctic Peninsula East Antarctica West Antarctica |
geographic_facet |
Antarctic The Antarctic Antarctic Peninsula East Antarctica West Antarctica |
genre |
Antarc* Antarctic Antarctic Peninsula Antarctica East Antarctica Ice Sheet West Antarctica |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Antarctica East Antarctica Ice Sheet West Antarctica |
op_source |
CASI |
op_relation |
Document ID: 20120002070 http://hdl.handle.net/2060/20120002070 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766186462716362752 |