Sentinel-3 FRM for Land ice
Over glaciers and ice sheets, satellite altimetry is mainly used for two purposes:
- To serve as absolute reference elevations of the snow/ice surface for deriving digital elevation models (DEMs) or for accurately correcting positioning biases in DEMs from other sources;
- To repeatedly measure surface elevation so precisely that ice thickness changes can be detected and mapped in space and time.
These two main applications put different demands on the satellite data. For the first purpose, a widespread coverage of data is needed over a relatively short amount of time, so that the snow/ice surface has not changed in the meantime. For the second purpose, precise repetition of ground-tracks (or frequent crossovers) might be as important as the elevation accuracy itself.
In the St3TART project, the Land Ice team will review existing measurement programs and instrumented stations on land ice in the Arctic and Antarctic, in context of validating the Copernicus Sentinel-3 altimetry measurements within the requirements for Fiducial Reference Measurements (FRM). Suitable FRM validation data will be identified and optimum procedures will be described for characterizing the performance of Copernicus Sentinel-3 measurements over various types of land ice, also keeping in mind the challenging environmental and logistical conditions of observational sites.
The review of existing FRMs and relevant validation efforts will form the basis for developing a roadmap for operational validation of Copernicus Sentinel-3 STM over land ice, considering existing in situ FRMs, candidate stations/data that can be upgraded or documented to become FRMs, as well as needs for new instruments and campaigns to develop future FRMs that could benefit the Copernicus Sentinel-3 validation.
- IGE/University of Grenoble