Retrieval of Snow Depth on Arctic Sea Ice From Surface‐Based, Polarimetric, Dual‐Frequency Radar Altimetry
2023
Willatt, Rosemary | Stroeve, Julienne C. | Nandan, Vishnu | Newman, Thomas | Mallett, Robbie | Hendricks, Stefan | Ricker, Robert | Mead, James | Itkin, Polona | Tonboe, Rasmus | Wagner, David N. | Spreen, Gunnar | Liston, Glen | Schneebeli, Martin | Krampe, Daniela | Tsamados, Michel | Demir, Oguz | Wilkinson, Jeremy | Jaggi, Matthias | Zhou, Lu | Huntemann, Marcus | Raphael, Ian A. | Jutila, Arttu | Oggier, Marc | Ilmatieteen laitos | Finnish Meteorological Institute | 0000-0001-6115-1687
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 r2 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 r2 0.15 or lower. r2 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.
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