Journal cover Journal topic
Earth System Science Data The Data Publishing Journal
Earth Syst. Sci. Data, 9, 849-860, 2017
https://doi.org/10.5194/essd-9-849-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
 
20 Nov 2017
Strong tidal variations in ice flow observed across the entire Ronne Ice Shelf and adjoining ice streams
Sebastian H. R. Rosier1, G. Hilmar Gudmundsson1, Matt A. King2, Keith W. Nicholls1, Keith Makinson1, and Hugh F. J. Corr1 1British Antarctic Survey, High Cross, Madingley Road, Cambridge, UK
2University of Tasmania, Hobart, Tasmania, Australia
Abstract. We present a compilation of GPS time series, including those for previously unpublished sites, showing that flow across the entire Ronne Ice Shelf and its adjoining ice streams is strongly affected by ocean tides. Previous observations have shown strong horizontal diurnal and semidiurnal motion of the ice shelf, and surface flow speeds of Rutford Ice Stream (RIS) are known to vary with a fortnightly (Msf) periodicity. Our new data set shows that the Msf flow modulation, first observed on RIS, is also found on Evans, Talutis, Institute, and Foundation ice streams, i.e. on all ice streams for which data are available. The amplitude of the Msf signal increases downstream of grounding lines, reaching up to 20 % of mean flow speeds where ice streams feed into the main ice shelf. Upstream of ice stream grounding lines, decay length scales are relatively uniform for all ice streams but the speed at which the Msf signal propagates upstream shows more variation. Observations and modelling of tidal variations in ice flow can help constrain crucial parameters that determine the rate and extent of potential ice mass loss from Antarctica. Given that the Msf modulation in ice flow is readily observed across the entire region at distances of up to 80 km upstream of grounding lines, but is not completely reproduced in any existing numerical model, this new data set suggests a pressing need to identify the missing processes responsible for its generation and propagation. The new GPS data set is publicly available through the UK Polar Data Centre at http://doi.org/10.5285/4fe11286-0e53-4a03-854c-a79a44d1e356.

Citation: Rosier, S. H. R., Gudmundsson, G. H., King, M. A., Nicholls, K. W., Makinson, K., and Corr, H. F. J.: Strong tidal variations in ice flow observed across the entire Ronne Ice Shelf and adjoining ice streams, Earth Syst. Sci. Data, 9, 849-860, https://doi.org/10.5194/essd-9-849-2017, 2017.
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Short summary
Tides can affect the flow of ice at hourly to yearly timescales. In some cases the ice responds at a different frequency than is found in the tidal forcing; for example, on Rutford Ice Stream the strongest response is at a fortnightly period. A new compilation of GPS data across the Ronne Ice Shelf and adjoining ice streams shows that this fortnightly modulation in ice flow is found across the entire region. Measurements of this kind can provide insights into ice rheology and basal processes.
Tides can affect the flow of ice at hourly to yearly timescales. In some cases the ice responds...
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