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| Titel |
Inferred basal friction and surface mass balance of the Northeast Greenland Ice Stream using data assimilation of ICESat (Ice Cloud and land Elevation Satellite) surface altimetry and ISSM (Ice Sheet System Model) |
| VerfasserIn |
E. Larour, J. Utke, B. Csatho, A. Schenk, H. Seroussi, M. Morlighem, E. Rignot, N. Schlegel, A. Khazendar |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 8, no. 6 ; Nr. 8, no. 6 (2014-12-15), S.2335-2351 |
| Datensatznummer |
250116392
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| Publikation (Nr.) |
 copernicus.org/tc-8-2335-2014.pdf |
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| Zusammenfassung |
| We present a new data assimilation method within the Ice Sheet System Model (ISSM) framework that is
capable of assimilating surface altimetry data from missions such as ICESat
(Ice Cloud and land Elevation Satellite)
into reconstructions of transient ice flow. The new method relies on
algorithmic differentiation to compute gradients of objective functions with
respect to model forcings. It is applied to the Northeast Greenland Ice
Stream, where surface mass balance and basal friction forcings are temporally
inverted, resulting in adjusted modeled surface heights that best fit
existing altimetry. This new approach allows for a better quantification of
basal and surface processes and a better understanding of the physical
processes currently missing in transient ice-flow models to better capture
the important intra- and interannual variability in surface altimetry. It
also demonstrates that large spatial and temporal variability is required in
model forcings such as surface mass balance and basal friction, variability
that can only be explained by including more complex processes such as
snowpack compaction at the surface and basal hydrology at the bottom of the
ice sheet. This approach is indeed a first step towards assimilating the
wealth of high spatial resolution altimetry data available from EnviSat,
ICESat, Operation IceBridge and CryoSat-2, and that which will be available in the
near future with the launch of ICESat-2. |
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