Dynamic Decomposition of Sub‐Daily Antarctic Sea‐Ice Concentration Change Using Passive Microwave Swath Observations

Abstract

Spaceborne radiometers have enabled global sea‐ice distribution observations since 1978, yet design choices associated with conventional daily averaged remote sensing products mean they do not resolve higher‐frequency variability that characterizes Antarctic sea ice. This study highlights the need for swath‐based sea‐ice concentration (SIC) and drift products to observe variability at sub‐daily timescales. We present operational motivations for such products and describe a methodological framework based on existing prototype data sets. By applying SIC retrieval algorithms directly to AMSR2 Level‐1R data in the Weddell Sea, the resulting concentration fields retain the native acquisition time of each satellite overpass. This avoids temporal averaging inherent in daily composites and allows observations to be interpreted as physically meaningful snapshots of the evolving ice cover. We further propose a method for dynamically decomposing SIC changes between successive swaths, revealing rapid variability in concentration and motion over ∼9 hr that is obscured in daily products. An ice‐type algorithm was also tested within the swath framework to address changes in pack ice where SIC is 100%. While operationally valuable, this approach interprets large radiometric changes as rapid category switching that appears unphysical over these short timescales. Several challenges remain before widespread implementation, including limited motion‐vector coverage in the marginal ice zone, inter‐swath radiometric variability, and uncertainties in ice‐type classification, underscoring the need for dedicated validation experiments. Swath‐derived data sets offer clear advantages for satellite validation and sea‐ice model evaluation by enabling direct comparison with sub‐daily model output and providing drift observations that better constrain rheological parameterizations and high‐frequency ice dynamics.