Stand-alone single-frequency GPS ice velocity observations on Nordenskiöldbreen, Svalbard

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 mea...

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Bibliographic Details
Published in:The Cryosphere
Main Authors: Den Ouden, M. A. G., Reijmer, C. H., Pohjola, Veijo A., van de Wal, R. S. W., Oerlemans, J., Boot, W.
Format: Article in Journal/Newspaper
Language:English
Published: Uppsala universitet, Luft-, vatten- och landskapslära 2010
Subjects:
Physical Geography
Naturgeografi
Nordenskiöldbreen
Svalbard
The Cryosphere
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-138217
https://doi.org/10.5194/tc-4-593-2010
Description
Summary: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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