The issue of glacier margin delineation is nicely illustrated by the image above (Sentinel-2, acquired 19 March 2022). The southwest quadrant of the image is obscured by clouds. North of the Reusch Crater, most of the white pixels depict patchy snow cover, excepting the two remaining portions of the Northern Ice Field (NIF; labeled). The NIF southern and eastern margins are partially visible due to ablation adjacent to the near-vertical ice wall, a typical situation observed days-weeks after snowfall events.
South of the crater, Furtwängler Glacier is only ice mass entirely within the caldera, shown within the red ellipse on the image above - and likely appearing slightly larger than reality, due adjacent snow. The white arc on the image south of the crater is entirely snow, extending from west of Uhuru Peak (yellow triangle) to east of Gilman's Point (green triangle). The southern margin of this arc coincides with the steep caldera rim; snow on the north side is shaded from sun during the boreal winter, yet almost entirely ablated on the south side.
The white patches high on the southern slope, above the yellow lines, are primarily glaciers: Kersten Glacier fragments directly south of Uhuru, the tiny Decken's Glacier finger to the east, and remnants of Rebmann Glacier just left of the label. Lower on the slope, below the yellow lines, we see a mixture of both snow-covered rock, and glacier fragments with snow cover.
Although the southern glacier margins cannot be precisely located on this image, it reveals that recession has continued despite relatively snowy conditions in recent years. For example, compare the image above with this view from July 2009.
With luck, we'll be back on Kibo in September, for a first-hand look at changes since our last fieldwork in February 2020 (including a Red Bull film).
