Lecture 17 Flashcards
How is mass balance measured?(altimetry)
Radar or lasar altimetry. Satellite or plane emits radio waves or laser beam, and measure the time it takes to reflect back
Gives distance from surface
repeats measurements to see how height changes
Problems of altimetry
- Can only detect relatively large changes
- Doesn’t work well with steep topograhpy
- Can’t account for density differences
What can gravity measurements be useful for and why is it not the most accurate
- Regional averages, but can’t be used for finer scale measurements of individual glaciers.
- Changes in gravity will change the distance of satellites
How is the glacier mass balance impacted by climate change?(High temp; air and ocean)
-High temps(air and ocean)
- Polar glaciers, not affected by air but significantly
affected by warming oceans
- Temperate glaciers - greatly affected by air and
ocean
How is the glacier mass balance impacted by climate change?(More precipitation)
Often increased accumulation in winter due to high water vapor content in atmosphere
How is the glacier mass balance impacted by climate change?( Feedback mechanism for more melt, and more snow)
- More melt -> lower albedo -> more energy absorbed
- More snow -> Higher albedo -> less energy absorbed
What would cause a glacier to have a greater driving stress?
Greater density of ice
Glacier dynamics: Basal sliding/ type of glacier it is important for
Whole thickness of ice slides over bedrock on a thin layer of water
Temperate glacier because base is close to 0 C
When will a glacier slide in terms of driving stress and basal drag
When driving stress is > basal drag
Glacier dynamics: internal deformation/ type of glacier it is important for
Under huge pressure, ice crystals rearrange parallel to surface of glacier and begin to slide over on another
Most important in polar glaciers bc base is under 0 C
When will a glacier deform in terms of driving stress and internal strength of ice
Driving stress > internal strength of ice glacier will deform
