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Arctic freeboard and snow depth from near-coincident CryoSat-2 and ICESat-2 (CRYO2ICE) observations: A first examination of winter sea ice during 2020-2022 (accepted)   
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  • Renée Mie Fredensborg Hansen,
  • Henriette Skourup,
  • Eero Rinne,
  • Knut Vilhelm Høyland,
  • Jack Christopher Landy,
  • Ioanna Merkouriadi,
  • Rene Forsberg
Renée Mie Fredensborg Hansen
Technical University of Denmark

Corresponding Author:[email protected]

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Henriette Skourup
National Space Insitute, DTU Space
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Eero Rinne
University Centre of Svalbard (UNIS)
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Knut Vilhelm Høyland
Norwegian University of Science and Technology
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Jack Christopher Landy
University of Tromsø - The Artic University of Norway
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Ioanna Merkouriadi
Finnish Meteorological Institute
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Rene Forsberg
Danmarks Tekniske Universitet
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Abstract

In the summer of 2020, ESA changed the orbit of CryoSat-2 to align periodically with NASA’s ICESat-2 mission, a campaign known as CRYO2ICE, which allows for near-coincident CryoSat-2 and ICESat-2 observations in space and time over the Arctic until summer 2022, where the CRYO2ICE Antarctic campaign was initiated. This study investigates the Arctic CRYO2ICE radar and laser freeboards acquired by CryoSat-2 and ICESat-2, respectively, during the winter seasons of 2020–2022, and derives snow depths from their differences along the orbits. Along-track snow depth observations can provide high-resolution snow depth distributions which are vital for air-ice-ocean heat and momentum transfer, understanding light transmission, and snow-ice-interactions. Generally, ICESat-2 is backscattered at a surface above the elevation of the CryoSat-2 signal. CRYO2ICE snow depths are thinner than the daily model- or passive-microwave-based snow depth composites used for comparison, with differences being most pronounced in the Atlantic and Pacific Arctic. Satellite-derived and model-based snow estimates show similar seasonal accumulation over FYI, but CRYO2ICE has limited seasonal accumulation over MYI which is linked to a slow increase in ICESat-2, and to some extent CryoSat-2, freeboards. We present a first estimation of along-track snow depth estimates with average uncertainty of 9 +/- 3 cm for 7-km segments, with random and systematic contributions of 7 and 4 cm. These observations show the potential for along-track dual-frequency observations of snow depth from the future Copernicus mission CRISTAL; but they also highlight uncertainties in radar penetration and the correlation length scales of snow topography that still require further research. 
12 Apr 2024Submitted to ESS Open Archive
16 Apr 2024Published in ESS Open Archive