Which determines the mass balance of a glacier?

Which determines the mass balance of a glacier?

Mass balance of a glacier (also referred to as “surface mass balance”) is the difference between the snow accumulated in the winter and the snow and ice melted over the summer. Seasonal and net mass balance can be calculated by extrapolating these ablation, height, and density measurements across the glacier area.

What is meant by glacial mass balance what are the basic inputs and outputs?

Mass balance is the total sum of all the accumulation (snow, ice, freezing rain) and melt or ice loss (from calving icebergs, melting, sublimation) across the entire glacier. If glaciers have a mass balance that is in equilibrium with climate, then the inputs are equal to the outputs.

What conditions lead to a glacier with negative and positive mass balance?

If the amount of melting across the glacier increases, then the glacier will have a negative mass balance, and the glacier will shrink. If the amount of snow or ice that the glacier receives increases but the amount of melt stays the same, then the glacier will grow. The glacier will have a positive mass balance.

What is glacier mass budget?

The glacial budget refers to the balance between the amount of inputs versus outputs affecting the glacial system. The glacier loses mass as evaporation will increase due to warmer temperatures and there will be melting at the snout. This part of a glacier is known as the zone of ablation.

How does mass balance affect glacier movement?

Glaciers gaining more mass than they lose will be in positive mass balance and will advance. Glaciers gaining and losing approximately the same amount of snow and ice are thought of as ‘in equilibrium’, and will neither advance nor recede.

What is equilibrium line in glacier?

The line that separates the accumulation and ablation areas is called the equilibrium line. The elevation of the equilibrium line depends on temperature, precipitation and the surrounding landscape. If the climate conditions remained constant, neither the equilibrium line nor the glacier margin would change.

What is the mass balance of a glacier?

Mass balance of a glacier (also referred to as “surface mass balance”) is the difference between the snow accumulated in the winter and the snow and ice melted over the summer. If the mass of snow accumulated on a glacier exceeds the mass of snow and ice lost during summer months, the mass balance is positive.

What is a mass balance study?

Mass balance studies are the snow and ice accounting system for glaciers, quantifying this change to understand the relationship between climate change and glaciers. Mass balance of a glacier (also referred to as “surface mass balance”) is the difference between the snow accumulated in the winter and the snow and ice melted over the summer.

Is remote sensing the best way to measure glacier mass balance?

Remote sensing of glacier mass balance is obviously a good alternative, as it allows many glaciers to be assessed using desk-based studies. It is a cheap and simple alternative to arduous fieldwork, but ground truthing of mass balance measurements will always be necessary.

What are the processes of ablation for a glacier?

The Glaciers as a System figure above summarises the key processes of ablation for a glacier. Glaciers lose mass through processes of ablation. Surface ablation processes include surface melt, surface meltwater runoff, sublimation, avalanching and windblown snow.

What is the equilibrium line of a glacier?

What is negative mass balance glacier?

Mass balance is the total sum of all the accumulation (snow, ice, freezing rain) and melt or ice loss (from calving icebergs, melting, sublimation) across the entire glacier. If the amount of melting across the glacier increases, then the glacier will have a negative mass balance, and the glacier will shrink.

How do you calculate net mass balance?

The net mass balance b is calculated by manual extrapolation of the measured balance data at stakes and pits to the total glacier surface (Fig. 9.8). Specific net mass balance b is calculated by dividing the mass balance by the glacier area and given in millimeter water equivalent (mm w.e.).

Which of the four seasons controls the glacial Budget and is most responsible for glacial advance and retreat?

More winter snow and less summer melting obviously favors the advance of the equilibrium line (and of the glacier’s leading-edge (or terminus), but of these two variables, it is the summer melt that matters most to a glacier’s budget. Cool summers promote glacial advance and warm summers promote glacial retreat [5].

Why does glacier mass balance vary spatially?

Temporal changes in the spatial distribution of the mass balance result primarily from changes in accumulation and melt along the surface. As a consequence, variations in the mass of glaciers reflect changes in climate and the energy fluxes at the Earth’s surface.

What is the accumulation zone of a glacier?

On a glacier, the accumulation zone is the area above the firn line, where snowfall accumulates and exceeds the losses from ablation, (melting, evaporation, and sublimation).

Do advancing glaciers have a negative mass balance?

Glacier mass balance and atmospheric circulation. By NASA. Mass balance can be thought of as the ‘health of a glacier’; glaciers losing more mass than they receive will be in negative mass balance and so will recede. Glaciers gaining more mass than they lose will be in positive mass balance and will advance.

What is the difference between Kames and drumlins?

Drumlin: Hills made of reshaped glacial till (not bedrock like a roche moutonee. Kame [Scots”comb.” Pronounced like English “came”]: Hills of stratified drift that form when a stream deposits sediment in a hole in the glacial ice. Kettle lake: This is essentially the opposite of a kame.

What is glacier budget?

The glacial budget describes how ice accumulates and melts on a glacier which ultimately determines whether a glacier advances or retreats.

How do glaciers lose mass?

Glaciers gain mass through snowfall and lose mass through melting and sublimation (when water evaporates directly from solid ice). Glaciers that terminate in a lake or the ocean also lose mass through iceberg calving.