57A185
Spatial and temporal characterization of sea-ice
deformation
Jennifer Hutchings, Andrew Roberts, Cathleen Geiger, Jacqueline
Richter-Menge
Corresponding author: Jennifer Hutchings –
jenny@iarc.uaf.edu
We investigate sea-ice deformation observed with
GPS-instrumented ice-drifting buoys deployed during late winter through summer
in the Beaufort Sea. The Sea Ice Experiment: Dynamic Nature of the Arctic
(SEDNA) was designed to investigate the relationship between strain rate, stress
and thickness redistribution of Arctic pack ice. In this presentation we focus
on one of the four objectives of SEDNA: ‘characterize the relationship
between, and coherence of, stress and strain rate at 10 km and 100 km’.
Two nested arrays of six GPS buoys each, which were deployed in late March 2007,
served as a backbone for the experiment. The two arrays were hexagons with
initial widths of 140 and 20 km. We assess whether there is a scaling
relationship between strain rate and the ice area over which the strain rate is
measured. Our findings demonstrate localization of strain rate, with increased
variability in the strain-rate field as spatial resolution increases. There are
changes in strain-rate power across scales related to the passage of weather
systems. During quiescent anti-cyclonic periods there is more power at the small
scale. With the passage of cyclones there is enhanced power at the large scale.
Coherence of strain rate between the two arrays is investigated with
cross-wavelet analysis. This shows a seasonal evolution in the coherence, which
is probably related to disconnection in the ice pack, reducing stress transfer,
during the progression through spring. Finally we present a coordinated
strain-rate and in situ measured stress time series, and identify the coherence
between strain rate (at two spatial scales) and internal ice stress, and how
this evolves in time. All these investigations provide information relevant to
the characterization of sea-ice rheological models and will be released as a
dataset designed for model validation.
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