Estimating snow depth over Arctic sea ice from calibrated dual-frequency radar freeboards

Snow depth on sea ice remains one of the largest uncertainties in sea ice thickness retrievals from satellite altimetry. Here we outline an approach for deriving snow depth that can be applied to any coincident freeboard measurements after calibration with independent observations of snow and ice fr...

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Bibliographic Details
Published in:The Cryosphere
Main Authors: I. R. Lawrence, M. C. Tsamados, J. C. Stroeve, T. W. K. Armitage, A. L. Ridout
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2018
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Online Access:https://doi.org/10.5194/tc-12-3551-2018
https://doaj.org/article/6f33b5fbe0e74415b9d51450d39b5f5c
Description
Summary:Snow depth on sea ice remains one of the largest uncertainties in sea ice thickness retrievals from satellite altimetry. Here we outline an approach for deriving snow depth that can be applied to any coincident freeboard measurements after calibration with independent observations of snow and ice freeboard. Freeboard estimates from CryoSat-2 (Ku band) and AltiKa (Ka band) are calibrated against data from NASA's Operation IceBridge (OIB) to align AltiKa with the snow surface and CryoSat-2 with the ice–snow interface. Snow depth is found as the difference between the two calibrated freeboards, with a correction added for the slower speed of light propagation through snow. We perform an initial evaluation of our derived snow depth product against OIB snow depth data by excluding successive years of OIB data from the analysis. We find a root-mean-square deviation of 7.7, 5.3, 5.9, and 6.7 cm between our snow thickness product and OIB data from the springs of 2013, 2014, 2015, and 2016 respectively. We further demonstrate the applicability of the method to ICESat and Envisat, offering promising potential for the application to CryoSat-2 and ICESat-2, which launched in September 2018.