The objectives of the Sea Ice CCI are to twofold:
(1) Provide quality-controlled ice concentration data sets for the Arctic and Antarctic from 1979 to present, based on passive microwave data.
(2) Provide Arctic sea ice thickness data sets based on radar altimeter data from 1993 to present and with the best possible validation and error characterization.
The climate research community (through GCOS) requires daily sea-ice concentration products at an accuracy of 5%. Such accuracy is not available consistently throughout the year based using any of the available passive microwave algorithms to extract sea-ice concentration. The accuracy might be achievable during periods of the Arctic winter, but the melting season is introducing larger uncertainties in the sea-ice concentration resulting in the GCOS requirement only being partially fulfilled.
Different satellites and instruments have been used to acquire the passive microwave data and together with data quality issues (especially during the melting season) these constitute challenges that need addressing in order to establish the sea-ice ECV.
Advances in the processing of radar altimeter data has though shown that these instruments can be used calculate low resolution sea ice thickness from measurements of ice freeboard. By using known values of ice density, show thickness and snow density, ice thickness can be retrieved for the winter months from 1993 to present. Knowledge of the natural variability of sea-ice thickness is critical for their representation in global climate models. The prediction of future changes in Arctic sea ice, and consequent effect on the ocean and atmosphere, relies on global climate models properly reproducing changes in sea-ice thickness.