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| Titel |
Ice Loss and Glacial Isostatic Adjustment Adjacent to the Drake Passage: 2003 - 2009 using GPS and GRACE |
| VerfasserIn |
Erik Ivins, Michael Watkins, Dah-Ning Yuan, Reinhard Dietrich, Gino Casassa, Axel Rülke |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250036957
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| Zusammenfassung |
| Accelerating ice mass losses are well-documented in the Southern Patagonian Icefield (SPI)
as well as in the northern Antarctic Peninsula (NAP). New GRACE data that allow continuity
with past mass change measurements therefore bear heavily on answering this question.
GRACE is an especially potent method because these data do not require independent
measurements of both the surface mass balance components and glacial fluxes. Annual rates
snow accumulation and glacier out-flux may both be increasing in the NAP, and there may be
particularly large uncertainty in the rate at which precipitation varies. Here we report mass
trends determined using a relatively new GRACE global-mascon treatment (GM) that
provides enhanced spatial resolution. For both the glaciers of NAP and NPI+SPI we
employ a cap sub-ensemble embedded within a global-mascon grid that models both
terrestrial geodetic uplift data and GRACE determined mass changes. The use of GPS
data allows ‘in situ’ correction for and glacial isostatic adjustment (GIA) ‘errors’
in determining present-day changes (PDC). Signals owing to both are contained
in the crustal motion and space gravimetric data. We solve for 250 km and 200
km Gauss-smoothed and GIA-corrected water equivalent height (WHE) rate that
minimizes chi-squared differences to both GPS and GRACE data in both NAP and
NPI+SPI, respectively. Mantle viscosity was estimated in Antarctica for the first time.
Bounds on the elastic lithosphere thicknesses for the two regions are similar: 20
< h < 45 km, but distinctly different for mantle viscosity for south Patagonia (4.0 Ã
1018 < η < 8.0 à 1018 Pa sec) versus the NAP (9.5 à 1018 < η < 5.5 à 1019 Pa
sec). Antarctic Peninsula ice mass loss is solved for: -41.5 Gt/yr in this process
combined data-model optimization. Patagonian losses during the observing period
Jan 2003 to March 2009 are -26 ± 6 Gt/yr and for the NAP: -41.5 ± 10 Gt/yr.
We conclude that both the NAP and the NPI+SPI are now sustaining long-term
inter-decadal ice loss and may be transitioning to a new warmer climate configuration. |
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