Ablation zone

The part of a glacier where melting, sublimation, and other losses exceed annual snow gains, producing a negative annual mass balance.

Glacier mass balance: The difference between a glacier’s gains and losses of mass over a specified period. The ablation zone is defined by negative annual mass balance.
Ablation stakes: Marked stakes inserted into glacier ice or snow to measure surface lowering or accumulation. Stake readings directly measure ice and snow loss within the zone.
Glacier retreat: The landward or upslope withdrawal of a glacier’s terminus as its ice extent decreases. Persistent losses in the ablation zone can reduce glacier length and area.
Jakobshavn Glacier: A major outlet glacier in western Greenland, also known as Sermeq Kujalleq. Its changing surface and terminus illustrate losses in a large, fast-flowing glacier.
Debris-covered glacier: A glacier whose surface is partly covered by rock debris transported by ice. Debris can suppress or enhance melt, making ablation-zone change difficult to predict.
Accumulation zone: The part of a glacier where annual gains, mainly snowfall, exceed losses. Its positive mass balance contrasts with the ablation zone’s net losses.
Glaciological mass-balance method: A method that estimates glacier mass change using field measurements of accumulation and ablation. Field surveys quantify losses across the ablation zone.
Glacier mass loss: A decrease in the total mass of a glacier over time. Ablation exceeding accumulation across a glacier contributes to net mass loss.
Mer de Glace: A valley glacier in the French Alps and the largest glacier in France. Its long record of retreat provides a visible case of glacier mass loss.
Supraglacial debris: Rock material lying on the surface of a glacier. Its thickness and distribution influence how much energy reaches glacier ice.

Linked from 6 pages