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Improved Arctic Sea Ice Freeboard Retrieval from Satellite Altimetry Using Optimized Sea Surface Decorrelation Scales

Landy, JC; Bouffard, J; Wilson, C; Rynders, S; Aksenov, Y; Tsamados, M; (2021) Improved Arctic Sea Ice Freeboard Retrieval from Satellite Altimetry Using Optimized Sea Surface Decorrelation Scales. Journal of Geophysical Research: Oceans , Article e2021JC017466. 10.1029/2021jc017466. (In press).

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Abstract

A growing number of studies are concluding that the resilience of the Arctic sea ice cover in a warming climate is essentially controlled by its thickness. Satellite radar and laser altimeters have allowed us to routinely monitor sea ice thickness across most of the Arctic Ocean for several decades. However, a key uncertainty remaining in the sea ice thickness retrieval is the error on the sea surface height (SSH) which is conventionally interpolated at ice floes from a limited number of lead observations along the altimeter’s orbital track. Here, we use an objective mapping approach to determine sea surface height from all proximal lead samples located on the orbital track and from adjacent tracks within a neighborhood of 30-220 (mean 105) kilometers. The patterns of the SSH signal’s zonal, meridional, and temporal decorrelation length scales are obtained by analyzing the covariance of historic CryoSat-2 Arctic lead observations, which match the scales obtained from an equivalent analysis of high-resolution sea ice-ocean model fields. We use these length scales to determine an optimal SSH and error estimate for each sea ice floe location. By exploiting leads from adjacent tracks, we can increase the sea ice radar freeboard precision estimated at orbital crossovers by up to 20%. In regions of high SSH uncertainty, biases in CryoSat-2 radar freeboard can be reduced by 25% with respect to coincident airborne validation data. The new method is not restricted to a particular sensor or mode, so it can be generalized to all present and historic polar altimetry missions.

Type: Article
Title: Improved Arctic Sea Ice Freeboard Retrieval from Satellite Altimetry Using Optimized Sea Surface Decorrelation Scales
DOI: 10.1029/2021jc017466
Publisher version: https://doi.org/10.1029/2021JC017466
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Satellite Altimetry, Arctic Ocean, Sea Ice, Sea Surface Height, Freeboard, CryoSat-2
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/10139077
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