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Satellite passive microwave sea-ice concentration data set intercomparison: closed ice and ship-based observations

ESA CCI algorithms are included in a systematic inter-comparison of 10 global sea-ice concentration from passive microwave observations for both the Arctic and the Antarctic - including, three new global sea-ice concentration (SIC) climate data records (CDRs), described in Lavergne et al.(2019).

Having compared against global year-round ship-based visual observations of the sea-ice cover and a global wintertime sea ice concentration data set for closed pack ice conditions, the study, led by S. Kern from the University of Hamburg found that the 10 products agree in terms of climate trends for both hemispheres at their native resolution, but differ quite dramatically in terms of sea ice extent and area.

Several factors explain the differences, relating to algorithm used, resolution, and weather filters. The authors urge users to use a filter to work consistently from one satellite to the next.

Fig 1: Northern hemisphere Arctic sea-ice area in winter.

The authors looked at the “minimum detected sea ice” for all 10 products. They found some products have jumps when changing satellite and that some filters interfere with the 15% limit, that is used in sea ice extent.

On the basis of this evaluation, the authors open a discussion about the overestimation of SIC in data products, with far-reaching consequences for surface heat flux estimations in winter.

Kern, S., Lavergne, T., Notz, D., Pedersen, L. T., Tonboe, R. T., Saldo, R., and Sørensen, A. M.: Satellite passive microwave sea-ice concentration data set intercomparison: closed ice and ship-based observations, The Cryosphere, 13, 3261–3307, https://doi.org/10.5194/tc-13-3261-2019, 2019.