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| Titel |
An assessment of the ICE6G_C (VM5A) glacial isostatic adjustment model |
| VerfasserIn |
Anthony Purcell, Paul Tregoning, Amaury Dehecq |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124246
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| Publikation (Nr.) |
 EGU/EGU2016-3648.pdf |
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| Zusammenfassung |
| The recent release of the next-generation global ice history model, ICE6G_C(VM5a) [Peltier
et al., 2015, Argus et al. 2014] is likely to be of interest to a wide range of disciplines
including oceanography (sea level studies), space gravity (mass balance studies), glaciology
and, of course, geodynamics (Earth rheology studies).
In this presentation I will assess some aspects of the ICE6G_C(VM5a) model and the
accompanying published data sets. I will demonstrate that the published present-day radial
uplift rates are too high along the eastern side of the Antarctic Peninsula (by ∼8.6 mm/yr)
and beneath the Ross Ice Shelf (by ∼5 mm/yr).
Further, the published spherical harmonic coefficients - which are meant to represent the
dimensionless present-day changes due to glacial isostatic adjustment (GIA) - will be shown
to contain excessive power for degree ≥ 90, to be physically implausible and to not represent
accurately the ICE6G_C(VM5a) model.
The excessive power in the high degree terms produces erroneous uplift rates when the
empirical relationship of Purcell et al. [2011] is applied but, when correct Stokes’ coefficients
are used, the empirical relationship will be shown to produce excellent agreement with the
fully rigorous computation of the radial velocity field, subject to the caveats first noted by
Purcell et al. [2011].
Finally, a global radial velocity field for the present-day GIA signal, and corresponding
Stoke’s coefficients will be presented for the ICE6G_C ice model history using the VM5a
rheology model. These results have been obtained using the ANU group’s CALSEA software
package and can be used to correct satellite altimetry observations for GIA over oceans and
by the space gravity community to separate GIA and present-day mass balance change
signals without any of the shortcomings of the previously published data-sets. We denote the
new data sets ICE6G_ANU. |
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