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| Titel |
Antarctic ice mass balance from satellite geodesy: understanding the signal beyond linear trends |
| VerfasserIn |
Martin Horwath, Ingo Sasgen, Benoît Legrésy, Frederique Remy, Fabien Blarel, Jean-Michel Lemoine, Henryk Dobslaw, Zdeněk Martinec, Maik Thomas |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250052522
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| Zusammenfassung |
| Satellite geodetic methods have revolutionized our knowledge on present-day mass changes
of the Antarctic ice sheet. These methods include Synthetic Aperture Radar (SAR) for flow
velocities, satellite altimetry (ENVISAT, ICESat, CryoSat-2) for surface height changes and,
finally since 2002, GRACE (Gravity Recovery and Climate Experiment) for mass changes.
While SAR applications provide "snapshots" of ice flow variations, ENVISAT radar altimetry
and GRACE satellite gravimetry observe variations in geometry and mass, respectively, in
about a monthly resolution, or even higher. Most analyses have concentrated on linear trends.
In this context, interannual variations, notably due to fluctuations of the surface mass balance
(SMB), appear as noise which complicates the interpretation of trends and their
comparison over different time spans. Atmospheric modeling of SMB has been
employed to evaluate this interannual "noise" in the trend analysis. Meanwhile, the
space geodetic techniques are mature enough to monitor the non-linear interannual
variations.
In this presentation we compare interannual signals from GRACE satellite gravimetry,
ENVISAT radar altimetry (RA) and atmospheric modeling. We use ENVISAT RA results
from the Along-Track Repeat Satellite RA approach and precipitation-minus-evaporation
estimates from ECMWF as an approximation for SMB. As the main result, the three
approaches provide consistent pictures of SMB-related nonlinear interannual variations. This
consistency gives confidence in either approach and confirms, in particular, that the nonlinear
variations in the geodetic time series mainly reflect actual signals of the ice sheet. By
the ECMWF atmospheric modeling data, geodetically observed interannual SMB
variations in West Antarctica and along the Antarctic Peninsula can be related to global
atmospheric conditions of the El Niño Southern Oscillation (ENSO). A synthesis of the
three approaches promises to add value to either datasets, to aid their interpretation
and to stimulate further improvements of the individual approaches, and thus to
refine our abilities to monitor and understand ongoing changes in the cryosphere. |
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