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| Titel |
Antarctic surface mass balance variations reflected by regional atmospheric modeling, satellite altimetry, and GRACE |
| VerfasserIn |
M. Horwath, M. R. van den Broeke, B. Legrésy, I. Sasgen, J. Bamber, F. Blarel |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068042
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| Zusammenfassung |
| Interannual variations of the Antarctic ice sheet due to surface mass balance (SMB)
fluctuations are important for estimates and interpretations of ice sheet mass balance.
Recent assessments mainly rely on atmospheric modeling, but SMB variations on an
ice-sheet scale are also reflected in satellite altimetry and GRACE satellite gravimetry
data.
All three approaches have their limitations. On the one hand, modeled interannual SMB
variations need observational validation, which has been limited by now. On the other hand,
the space-geodetic data do not exclusively reflect SMB phenomena, but also ice dynamics,
glacial isostatic adjustment, and errors. Moreover, quantifying ice mass changes from
altimetry requires assumptions on firn density and compaction. Finally, the spatial sensitivity
of GRACE is limited to a few hundred kilometers. Nonetheless, previous work has shown
promising qualitative agreement between interannual change patterns in ENVISAT radar
altimetry (RA) and GRACE and between regional-scale interannual signals from GRACE
and atmospheric modeling.
Here we present comprehensive comparisons between all three techniques for the
Antarctic ice sheet. We use the RACMO2/ANT high-resolution regional atmospheric model,
ENVISAT RA estimates from an advanced along-track repeat analysis, and GRACE
estimates from regional analyses based on different series of time-variable gravity field
solutions. The overlapping period of the three techniques is August 2002 to October
2010.
The high-resolution (27 km) spatial representations of interannual phenomena in
ENVISAT RA and RACMO2/ANT match well for many regions, and show good agreement
with the larger-scale patterns of mass varations determined with GRACE. We quantify this
agreement by statistical parameters. Next, we combine all three techniques to characterize
and quantify selected temporal SMB anomalies, such as an excess accumulation in West
Antarctica and Wilkes Land in September/October 2005. The presented overall agreement
indicates that, to a large extent, interannual signals in ENVISAT and GRACE are well
understood as temporal SMB variations represented by RACMO2/ANT. Remaining
differences between the three techniques help us to assess their limitations, and
may guide further improvement in observing and modeling SMB-related ice sheet
variations. |
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