Retrieval of Snow Depth on Arctic Sea Ice From Surface‐Based, Polarimetric, Dual‐Frequency Radar Altimetry
Rosemary Willatt, Julienne Strœve, Vishnu Nandan, Thomas Newman, Robbie Mallett, Stefan Hendricks, Robert Ricker, James B. Mead, Polona Itkin, Rasmus Tonboe, David N. Wagner, Gunnar Spreen, Glen E. Liston, Martin Schneebeli, Daniela Krampe, Michel Tsamados, Oguz Demir, Jeremy Wilkinson, Matthias Jaggi, Lu Zhou, Marcus Huntemann, Ian Raphael, Arttu Jutila, Marc Oggier
Abstract
Abstract Snow depth on sea ice is an Essential Climate Variable and a major source of uncertainty in satellite altimetry‐derived sea ice thickness. During winter of the MOSAiC Expedition, the “KuKa” dual‐frequency, fully polarized Ku‐ and Ka‐band radar was deployed in “stare” nadir‐looking mode to investigate the possibility of combining these two frequencies to retrieve snow depth. Three approaches were investigated: dual‐frequency, dual‐polarization and waveform shape, and compared to independent snow depth measurements. Novel dual‐polarization approaches yielded r 2 values up to 0.77. Mean snow depths agreed within 1 cm, even for data sub‐banded to CryoSat‐2 SIRAL and SARAL AltiKa bandwidths. Snow depths from co‐polarized dual‐frequency approaches were at least a factor of four too small and had a r 2 0.15 or lower. r 2 for waveform shape techniques reached 0.72 but depths were underestimated. Snow depth retrievals using polarimetric information or waveform shape may therefore be possible from airborne/satellite radar altimeters.