Year: 2025
Type: preprint
Abstract: Sea-ice thickness is a key component of the global climate system, regulating the exchange of heat, moisture, and carbon between the atmosphere and ocean. Satellite radar altimetry has greatly advanced freeboard retrieval and, through freeboard-to-thickness conversion, our ability to estimate sea-ice thickness. Although the physical principle underlying radar-wave propagation through snow, and the associated need for a slow-down correction are universal in both hemispheres, existing retrieval schemes were developed and validated using Arctic snow climatologies; robust application to the Antarctic therefore requires Antarctic-specific snow thickness, density, and stratigraphy inputs. Here, we present a 14-year intercomparison of four satellite products (LEGOS, CCI, CSAO, and Cryo-TEMPO) derived from Envisat and CryoSat-2. All products reproduce the broad spatial pattern of higher freeboards in the Weddell and Ross seas and lower values in the Indian and Amundsen–Bellingshausen sectors. LEGOS consistently yields the largest radar and sea-ice freeboards, particularly over thick, snow-covered ice, whereas Cryo-TEMPO provides the smallest sea-ice freeboards. Using the CCI product as an independent reference, these differences are reported as relative offsets without inferring the absolute truth. Temporal analysis reveals a sensor-related step, with monthly mean radar freeboard increasing by 2–3 cm between Envisat/RA-2 and CryoSat-2/SIRAL, consistent with basin-scale mission intercomparisons. While inter-product correlations are moderate to high, persistent absolute offsets highlight the need to refine Antarctic snow climatologies, improve sensor cross-calibration, and update retrieval algorithms to reduce uncertainties in Antarctic sea-ice thickness.
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
OpenAlex ID: W4414200379
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