EGUsphere

Copernicus Publications

Göttingen, Germany

10.5194/egusphere-2026-4530

Reconciling Arctic sea ice roughness across four observing platforms: a resolution transfer function and the stability of spectral shape over six decades

Yang

Lei

https://orcid.org/0000-0002-6503-0505

¹ Zhu

Lin

https://orcid.org/0000-0002-1985-356X

Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China

Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao 266101, China

05 11 2026

2026 1 24

2026

This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/

This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-4530/

The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-4530/egusphere-2026-4530.pdf

Sea ice roughness is measured by platforms whose spatial resolutions differ by two orders of magnitude, and the resulting estimates disagree by a factor of four, which has prevented the assembly of a consistent long-term record. Here we analyse ice topography from four platforms within a single broken power law spectral framework: submarine upward-looking sonar (5470 profiles, 43 cruises, 1960–2005), MOSAiC airborne laser scanning (55256 transects), under-ice remotely operated vehicle (ROV) multibeam (52264 transects from 36 dives), and ICESat-2 altimetry (25740 segments). The fourfold spread in the slope-to-amplitude ratio z2/z1 collapses onto a single resolution degradation curve, z2/z1 = 0.218 Δx-0.46 (R2 = 0.92), whose exponent follows analytically from the observed spectral shape rather than being fitted freely; the curve provides a transfer function for inter-calibrating roughness estimates between platforms with effective footprints of 0.5–20 m. The resolution-independent spectral parameters (β1 ≈ -0.5, β2 ≈ -2.2, λbreak ≈ 99 m) are consistent across all four platforms and both ice surfaces, and show no significant trend over the 45-year submarine record despite a halving of mean ice thickness, although that record can only exclude changes larger than about 160 % of the median exponent at 80 % power. Eighty-five paired surface–bottom observations spanning a full MOSAiC year show that the isostatic approximation holds at the derivative level (z2/z1 surface-to-bottom ratio 0.99 ± 0.14, against 0.28 for the amplitude z1), so under-ice morphology can be inferred from satellite surface measurements. That fidelity is seasonal: the ratio is 0.94 ± 0.07 from October to May but reverses to 1.14 ± 0.10 from June to September, when surface melt and basal melt together leave the surface sharper than the underside. Roughness amplitude and spectral shape therefore respond to forcing on different terms: z1 varies sevenfold over the seasonal cycle and has declined with the ice cover, while the shape parameters remain stable to within the tested bounds.