Nab, Carmen Julia;
(2025)
The point of snow return: CryoSat-2 radar penetration over Arctic sea ice.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Accurate monitoring and modelling of Arctic sea ice thickness is vital to understanding the region’s effects on regional and global climates, shipping routes, and wildlife living on and under the ice. Satellite radar altimeters offer a valuable tool for estimating sea ice thickness, where the travel time of a radar pulse to the sea ice surface and back is measured to obtain the radar freeboard; a proxy for the height of the ice above the surrounding sea water. The method for converting radar freeboard estimates to sea ice thickness requires an assumption regarding the fractional depth of the snowpack penetrated by radar waves (α), which then return to the instrument. All current winter sea ice thickness retrieval methods assume full Ku-band radar penetration through the snowpack (α = 1). A growing body of research has shown this not to be the case in reality, with snow and weather properties affecting the ability of radar waves to penetrate the snowpack. Uncertainties in the radar freeboard and assumed radar penetration contribute to the overall error in calculated sea ice thickness, with an overestimation of α causing an overestimation in sea ice thickness, without competing biases. This thesis aims to improve our understanding of CryoSat-2 snow penetration over Arctic sea ice and its impact on seasonal ice thickness forecasts. The first two results chapters of this thesis focus on CryoSat-2's ability to penetrate the Arctic snowpack and retrieve the radar freeboard. The first results chapter represents the first calculation of α at synoptic timescales, whilst the second shows the possible improvements in capturing interannual sea ice thickness variability when using these α values in the thickness processing chain. The second results chapter introduces a novel methodology for evaluating the skill of sea ice thickness products. Finally, the last results chapter highlights the sensitivity of seasonal forecasts to the sea ice thickness parameterisation used in a data assimilation framework.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | The point of snow return: CryoSat-2 radar penetration over Arctic sea ice |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10205957 |
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