The ESA CCI Sea Ice project will combine and extend ongoing research to develop improved and validated time series of ice concentration and ice thickness for use in climate research.
Since sea ice is a sensitive climate indicator with large seasonal and regional variability, the climate research community requires long-term and regular observations of these key ice parameters in both the Arctic and Antarctic. The ESA CCI Sea Ice project will deliver global data sets to support climate research and monitoring according to the GCOS requirements for generation of satellite-based data sets and products.
Users of sea ice thickness estimates also include commercial players planning ship and offshore operations in ice covered waters. As ice thickness influences loads on structures, it is much sought after during infrastructure design phases and when planning operations.
Advances in the processing of ERS and Envisat radar altimeter data has though shown that these instruments can be used to calculate low-resolution sea ice thickness data from measurements of ice freeboard. In addition to ERS and Envisat, in CCI Phase 2 estimates will also be derived from Cryosat-2 data.
Role of the Polar TEP
Operational processing chains will benefit from easier access to data, combined with access to scalable processing resources.
The Polar TEP is of special interest to the sea ice thickness CCI since the European radar altimeter data is an input both for ice sheet elevation change and sea ice thickness retrieval. Some of the processing steps are identical or easily adapted from one application to another. In addition functionality for sea ice related altimeter data processing (such as sea ice dedicated re-trackers and ice type detection from waveform shape) may also be implemented. Also the iceberg detection from radar altimeter data is based on the same input data and waveform characterisation as sea ice thickness retrieval as the “iceberg echoes” are recognised and discarded from the SIT processing.
Computationally, the heaviest part of the altimeter to SIT chain is the so called “retracking”. A retracker fits a mathematical model to the waveform, and using this model calculates the range representing the target surface.
Lastly, the developers of altimeter sea ice thickness retrieval algorithms would benefit from the TEP. Currently, researchers tend to build and test their tools on a local computer with data downloaded on a local disk. Having a TEP that would allow the testing of their modules (for example retrackers or freeboard to thickness conversion) jointly with other researchers, which would allow the researchers to share and demonstrate their ideas and novel tools within their research community much faster than is currently possible.
Furthermore the Polar TEP should include visualisation and data export tools for sea ice thickness. These will include averaging (both spatial and temporal) of processor outputs.