Simulated Ka- and Ku-band radar altimeter height and freeboard estimation on snow-covered Arctic sea ice Journal Article uri icon

Overview

abstract

  • Abstract. Owing to differing and complex snow geophysical properties, radar; waves of different wavelengths undergo variable penetration through; snow-covered sea ice. However, the mechanisms influencing radar altimeter; backscatter from snow-covered sea ice, especially at Ka- and Ku-band; frequencies, and the impact on the Ka- and Ku-band radar scattering horizon; or the “track point” (i.e. the scattering layer depth detected by the radar; re-tracker) are not well understood. In this study, we evaluate the Ka- and; Ku-band radar scattering horizon with respect to radar penetration and ice; floe buoyancy using a first-order scattering model and the Archimedes; principle. The scattering model is forced with snow depth data from the; European Space Agency (ESA) climate change initiative (CCI) round-robin data; package, in which NASA's Operation IceBridge (OIB) data and climatology are; included, and detailed snow geophysical property profiles from the Canadian; Arctic. Our simulations demonstrate that the Ka- and Ku-band track point; difference is a function of snow depth; however, the simulated track point; difference is much smaller than what is reported in the literature from the; Ku-band CryoSat-2 and Ka-band SARAL/AltiKa satellite radar altimeter; observations. We argue that this discrepancy in the Ka- and Ku-band track; point differences is sensitive to ice type and snow depth and its; associated geophysical properties. Snow salinity is first increasing the Ka-; and Ku-band track point difference when the snow is thin and then; decreasing the difference when the snow is thick (>0.1 m). A; relationship between the Ku-band radar scattering horizon and snow depth is; found. This relationship has implications for (1) the use of snow climatology; in the conversion of radar freeboard into sea ice thickness and (2) the; impact of variability in measured snow depth on the derived ice thickness.; For both (1) and (2), the impact of using a snow climatology versus the actual; snow depth is relatively small on the radar freeboard, only raising the; radar freeboard by 0.03 times the climatological snow depth plus 0.03 times; the real snow depth. The radar freeboard is a function of both radar; scattering and floe buoyancy. This study serves to enhance our understanding; of microwave interactions towards improved accuracy of snow depth and sea ice thickness retrievals via the combination of the currently operational and; ESA's forthcoming Ka- and Ku-band dual-frequency CRISTAL radar altimeter; missions.;

publication date

  • April 13, 2021

Date in CU Experts

  • June 28, 2021 10:05 AM

Full Author List

  • Tonboe RT; Nandan V; Yackel J; Kern S; Pedersen LT; Stroeve J

author count

  • 6

Other Profiles

Electronic International Standard Serial Number (EISSN)

  • 1994-0424

Additional Document Info

start page

  • 1811

end page

  • 1822

volume

  • 15

issue

  • 4