Abstract
Abstract. Antarctic sea ice kinematics plays a crucial role in shaping the
Southern Ocean climate and ecosystems. Satellite passive-microwave-derived
sea ice motion data have been used widely for studying sea ice motion and
deformation, and they provide daily global coverage at a relatively low spatial resolution (in the order of 60 km × 60 km). In the Arctic,
several validated datasets of satellite observations are available and used
to study sea ice kinematics, but far fewer validation studies exist for the
Antarctic. Here, we compare the widely used passive-microwave-derived
Antarctic sea ice motion product by Kimura et al. (2013) with buoy-derived
velocities and interpret the effects of satellite observational
configuration on the representation of Antarctic sea ice kinematics. We
identify two issues in the Kimura et al. (2013) product: (i) errors in two
large triangular areas within the eastern Weddell Sea and western Amundsen
Sea relating to an error in the input satellite data composite and (ii) a
more subtle error relating to invalid assumptions for the average sensing
time of each pixel. Upon rectification of these, performance of the daily
composite sea ice motion product is found to be a function of latitude,
relating to the number of satellite swaths incorporated (more swaths further
south as tracks converge) and the heterogeneity of the underlying satellite
signal (brightness temperature here). Daily sea ice motion vectors
calculated using ascending- and descending-only satellite tracks (with a
true ∼ 24 h timescale) are compared with the widely used
combined product (ascending and descending tracks combined together, with an
inherent ∼ 39 h timescale). This comparison reveals that
kinematic parameters derived from the shorter-timescale velocity datasets
are higher in magnitude than the combined dataset, indicating a high degree
of sensitivity to observation timescale. We conclude that the new
generation of “swath-to-swath” (S2S) sea ice velocity datasets,
encompassing a range of observational timescales, is necessary to advance
future research into sea ice kinematics.
Subject
Earth-Surface Processes,Water Science and Technology
Cited by
3 articles.
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