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| Titel |
Stand-alone single-frequency GPS ice velocity observations on Nordenskiöldbreen, Svalbard |
| VerfasserIn |
M. A. G. Ouden, C. H. Reijmer, V. Pohjola, R. S. W. Wal, J. Oerlemans  , W. Boot |
| 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 ; 4, no. 4 ; Nr. 4, no. 4 (2010-12-15), S.593-604 |
| Datensatznummer |
250001907
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| Publikation (Nr.) |
 copernicus.org/tc-4-593-2010.pdf |
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| Zusammenfassung |
| Precise measurements of ice-flow velocities are necessary for a proper
understanding of the dynamics of glaciers and their response to climate
change. We use stand-alone single-frequency GPS receivers for this purpose.
They are designed to operate unattended for 1–3 years, allowing
uninterrupted measurements for long periods with hourly temporal resolution.
We present the system and illustrate its functioning using data from 9 GPS
receivers deployed on Nordenskiöldbreen, Svalbard, for the period
2006–2009. The accuracy of the receivers is 1.62 m based on the standard
deviation in the average location of a stationary reference station (NBRef).
Both the location of NBRef and the observed flow velocities agree within one
standard deviation with DGPS measurements. Periodicity (6, 8, 12, 24 h) in
the NBRef data is largely explained by the atmospheric, mainly ionospheric,
influence on the GPS signal. A (weighed) running-average on the observed
locations significantly reduces the standard deviation and removes high
frequency periodicities, but also reduces the temporal resolution. Results
show annual average velocities varying between 40 and 55 m yr−1 at
stations on the central flow-line. On weekly to monthly time-scales we
observe a peak in the flow velocities (from 60 to 90 m yr−1) at the
beginning of July related to increased melt-rates. No significant lag is
observed between the timing of the maximum speed between different stations.
This is likely due to the limited temporal resolution after averaging in
combination with the relatively small distance (max. ±13 km) between
the stations. |
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