Zakharova, Elena A; Fleury, Sara; Guerreiro, Kévin; Willmes, Sascha; Rémy, Frédérique; Kouraev, Alexei V; Heinemann, Günther (2016): Monthly Arctic sea ice lead fraction in 0.5° x 0.5° resolution from SARAL/Altika altimeter, link to datasets in NetCDF 4 format [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.862882,

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Supplement to: Zakharova, EA et al. (2015): Sea ice leads detection using SARAL/AltiKa altimeter. Marine Geodesy, 38(sup1), 522-533, https://doi.org/10.1080/01490419.2015.1019655

Sea ice leads play an essential role in ocean-ice-atmosphere exchange, in ocean circulation, geochemistry, and in ice dynamics. Their precise detection is crucial for altimetric estimations of sea ice thickness and volume. This study evaluates the performance of the SARAL/AltiKa (Satellite with ARgos and ALtiKa) altimeter to detect leads and to monitor their spatio-temporal dynamics. We show that a pulse peakiness parameter (PP) used to detect leads by Envisat RA-2 and ERS-1,-2 altimeters is not suitable because of saturation of AltiKa return echoes over the leads. The signal saturation results in loss of 6–10% of PP data over sea ice. We propose a different parameter—maximal power of waveform—and define the threshold to discriminate the leads. Our algorithm can be applied from December until May. It detects well the leads of small and medium size from 200 m to 3–4 km. So the combination of the high-resolution altimetric estimates with low-resolution thermal infra-red or radiometric lead fraction products could enhance the capability of remote sensing to monitor sea ice fracturing.

Spatial Coverage: 65° N - 82° N, 180° E - 180° W

Spatial Resolution: 0.5° x 0.5°

Temporal Coverage: April 2013 to April 2016

Temporal Resolution: 1 month

Algorithm validity period: December - May. Comments: in November and June the lead fraction should be taken with caution. In July - October the algorithm fails.