Late Summer Arctic Sea Ice Surface Roughness Signatures in C-Band SAR Data

In this study, we investigate the influence of Arctic sea ice surface roughness on full polarimetric C-band SAR features in the late summer season. Surface roughness measured from a helicopter-borne laser altimeter is compared to 14 individual SAR features holding a documented theoretical or empirical relation to surface roughness. Three C-band Radarsat-2 SAR scenes, covering a study area with both first-year ice and old ice surfaces with a variety of roughnesses are included in the study. Nine of the individual investigated SAR features were, in at least one of the scenes, correlated to laser altimeter measured root-mean-square height with a Spearman's correlation coefficient better than ±0.6. The strength of the correlation varied from scene to scene, and the between-scene variation was explained by differences in incidence angle, changes in the meteorological conditions, and changes in the microscale surface roughness of both the sea ice and the melt pond surfaces. We highlight that knowledge of temperature and weather history could improve the quality of surface roughness interpretation in SAR scenes in the late summer. The findings are important for improved interpretation of satellite SAR sea ice imagery, relevant to, e.g., shipping and detection of sea ice changes in the context of climate research and monitoring.