Ablation zone
Encyclopedia
Ablation zone refers to the low altitude area of a glacier
or ice sheet
where there is a net loss in ice mass due to melting, sublimation, evaporation, or calving
. The ablation zone is delineated by the equilibrium line altitude (ELA), or snow line
, which separates the ablation zone and the high altitude accumulation zone
. The ablation zone often contains meltwater
features such as supraglacial, englacial, and subglacial streams. The seasonally melting glacier deposits much sediment at its fringes in the ablation area. Ablation constitutes a key part of the glacier mass balance
.
Glacier mass balance is determined by the amount of snow and ice gained in the winter in the accumulation zone, and by the amount of ice melted or calved in the ablation zone. Often mass balance measurements are made in the ablation zone using snow stakes.
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
or ice sheet
Ice sheet
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² , thus also known as continental glacier...
where there is a net loss in ice mass due to melting, sublimation, evaporation, or calving
Ice calving
Ice calving, also known as glacier calving or iceberg calving, is a form of ice ablation or ice disruption. It is the sudden release and breaking away of a mass of ice from a glacier, iceberg, ice front, ice shelf, or crevasse...
. The ablation zone is delineated by the equilibrium line altitude (ELA), or snow line
Snow line
The climatic snow line is the point above which snow and ice cover the ground throughout the year. The actual snow line may seasonally be significantly lower....
, which separates the ablation zone and the high altitude accumulation zone
Accumulation zone
On a glacier, the accumulation zone is the area above the firn line, where snowfall accumulates and exceeds the losses from ablation, . The annual Glacier equilibrium line separates the accumulation and ablation zone annually...
. The ablation zone often contains meltwater
Meltwater
Meltwater is the water released by the melting of snow or ice, including glacial ice and ice shelfs over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing...
features such as supraglacial, englacial, and subglacial streams. The seasonally melting glacier deposits much sediment at its fringes in the ablation area. Ablation constitutes a key part of the glacier mass balance
Glacier mass balance
Crucial to the survival of a glacier is its mass balance, the difference between accumulation and ablation . Climate change may cause variations in both temperature and snowfall, causing changes in mass balance. Changes in mass balance control a glacier's long term behavior and is the most...
.
Glacier mass balance is determined by the amount of snow and ice gained in the winter in the accumulation zone, and by the amount of ice melted or calved in the ablation zone. Often mass balance measurements are made in the ablation zone using snow stakes.
