24 Oct 2023
 | 24 Oct 2023

Linear Ice Fraction: Sea Ice Concentration Estimates from the ICESat-2 Laser Altimeter

Christopher Horvat, Ellen Buckley, Madelyn Stewart, Poom Yoosiri, and Monica M. Wilhelmus

Abstract. Sea ice coverage is a key indicator of changes in the global climate. Estimates of sea ice area and extent are primarily derived from satellite measurements of surface microwave emissions, from which local sea ice concentration (SIC) is derived. Passive microwave (PM) satellite sensors remain the sole global product for understanding SIC variability. Using a dataset of more than 27,000 high-resolution airborne optical images, we first examine biases in commonly-used products that emerge from challenges in sampling thin sea ice fractures and melt ponds on the sea ice surface. We show that the ICESat-2 (IS2) laser altimeter effectively samples these surface features and we develop a new, independent SIC product, which we term the Linear Ice Fraction (LIF). On monthly timescales, we show using an emulator that the LIF product offers an independent estimate of sea ice concentration over 60 % of the Arctic sea ice cover with similar-or-better error qualities compared to PM data. IS2 and its high-precision measurements of the sea ice surface  should be considered for augmenting PM-SIC measurements in the future.  

Christopher Horvat et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2312', Anonymous Referee #1, 28 Nov 2023
  • RC2: 'Comment on egusphere-2023-2312', Anonymous Referee #2, 06 Dec 2023

Christopher Horvat et al.

Christopher Horvat et al.


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Short summary
The decline of sea ice area variability is a leading indicator of climate change, and accurate measurement of sea ice area are of high importance. We develop new measurement of sea ice area coverage using the ICESat-2 laser altimeter, typically used to measure the height of the ice surface. The new method performs as well or better than typical passive microwave measurements, especially for sea ice populated with thin fractures in winter.