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| Titel |
Co-registration and bias corrections of satellite elevation data sets for quantifying glacier thickness change |
| VerfasserIn |
C. Nuth, A. Kääb |
| 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 ; 5, no. 1 ; Nr. 5, no. 1 (2011-03-29), S.271-290 |
| Datensatznummer |
250002286
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| Publikation (Nr.) |
 copernicus.org/tc-5-271-2011.pdf |
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| Zusammenfassung |
| There are an increasing number of digital elevation models (DEMs) available
worldwide for deriving elevation differences over time, including vertical
changes on glaciers. Most of these DEMs are heavily post-processed or merged,
so that physical error modelling becomes difficult and statistical error
modelling is required instead. We propose a three-step methodological
framework for assessing and correcting DEMs to quantify glacier elevation
changes: (i) remove DEM shifts, (ii) check for elevation-dependent biases,
and (iii) check for higher-order, sensor-specific biases. A simple, analytic
and robust method to co-register elevation data is presented in regions where
stable terrain is either plentiful (case study New Zealand) or limited (case
study Svalbard). The method is demonstrated using the three global elevation
data sets available to date, SRTM, ICESat and the ASTER GDEM, and with
automatically generated DEMs from satellite stereo instruments of ASTER and
SPOT5-HRS. After 3-D co-registration, significant biases
related to elevation were found in some of the stereoscopic DEMs. Biases
related to the satellite acquisition geometry (along/cross track) were
detected at two frequencies in the automatically generated ASTER DEMs. The
higher frequency bias seems to be related to satellite jitter, most
apparent in the back-looking pass of the satellite. The origins of the more
significant lower frequency bias is uncertain. ICESat-derived elevations are
found to be the most consistent globally available elevation data set
available so far. Before performing regional-scale glacier elevation change
studies or mosaicking DEMs from multiple individual tiles (e.g. ASTER GDEM),
we recommend to co-register all elevation data to ICESat as a global vertical
reference system. |
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