The grounding line of the Antarctic Ice Sheet is that part where the glaciers exporting the ice down the continent loose contact to the ground and become a floating ice shelf. Examples of such ice shelves are the Ronne-Filchner Ice Shelf, the Ross Ice Shelf, and the Amery Ice Shelf.
Accurate knowledge of the grounding line is important for a correct calculation of a) the mass budget of the Antarctic ice sheet and the ice shelves, and b) the amount of melt water released into the ocean due to melt of the ice by the relatively warm water entering the caverns underneath the floating ice shelf.
The retrieval of the grounding line position is based using differential interferometric synthetic aperture radar (DInSAR). Basically one seeks to find the transition zone between the merely constantly downslope moving glacier on land and the floating ice shelf, which is influenced by ocean currents and tides and therefore shows a substantial, temporally variable vertical motion.
This data set (MEaSUREs version 2) is based on data of the following satellite SAR sensors: RADARSAT-1 und -2 SAR, ALOS Palsar, ERS1/2 SAR, COSMO SkyMed, und Sentinel-1A.
Details can be taken from the references down below.
Last update of the data set: November 4, 2016