What units of measurement are used for measuring a glacier?

Answer 1

There are many ways to do this. The ice sheets are very remote places, so remote sensing methods are heavily relied upon. Satellite altimeters very precisely measure the distance between the satellite and the surface of the earth, and a temporal record gives changes in the elevation of the land, and therefore the ice sheet (with terms such as isostatic rebound accounted for). Passive microwave sensors are extremely good at detecting the onset of melt in the spring. They measure radiation emitted from the ice sheet in the microwave part of the spectrum, which is very sensitive to the transition from ice to water. This gives useful information about the spatial and temporal characteristics of ice melt, especially onset. Also, visible sensors can be used to some extent.

Much of the remaining work is done on the ground. Since melt water has to go somewhere, runoff is measured at the edge of glaciers at certain spots near the ice edge, and this provides a useful gauge of how melt is changing through time. Mass balance studies are also carried out on the ice sheet through snow pits and transects, for example, to see how the surface is changing in spot measurement. Radars are sometimes used on the ground to give an image of the ice sheet and can be compared to past data.

All of this data is often integrated into computer models that simulate, given these data and others such as heat fluxes and precipitation, how the ice sheet has been behaving and is likely to change in the future. Ground data serves as the validation for this.

Answer 2

That depends what aspect of the glacier you want to measure. For example:

• Length or width might be measured in meters or kilometers.
• Volume might be measured in cubic meters.
• Temperature might be measured in Kelvin, or in degrees centigrade.

Answer 3

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Answer 4

They keep track and check every few years