Sentinel-2 supraglacial melt-pond water-index image (Galaxy Training Network — Introduction to Image Analysis, Earth-observation path)

A single-band, 16-bit ice-adapted normalised-difference water-index image of supraglacial melt ponds on the south-west Greenland ice sheet, prepared as the Earth-observation input for the Galaxy Training Network tutorial Introduction to Image Analysis using Galaxy (gxy.io/GTN:T00181). NDWIice = (blue − red)/(blue + red) (Williamson et al. 2018, doi:10.5194/tc-12-3045-2018), computed from a Sentinel-2 Level-2A scene (tile T22WEV, 2019-07-23) over the Russell–Leverett ablation zone and rescaled to 16-bit so that melt ponds are the bright objects — the Earth-observation analogue of the bright cell nuclei the tutorial uses. The same threshold → label → count steps then count melt ponds. Full provenance, the preprocessing pipeline, the Galaxy run, and validation against an independently published lake map are in the OSCARS–FIESTA example repository: annefou/fiesta-galaxy-meltponds-eo. Contains modified Copernicus Sentinel data 2019.