REMOTE SENSING OF THE CRYOSPHERE: EXERCISES

1. Glacier outlines:Without conferring with your classmates, mark on the following imageswhere you would consider the glacier outline to be:

A.

B.

C.

Now, compare your outlines with others. How do they differ? Where do they differ? Provide some reasons for the differences. What additional information might you use to improve the accuracy of your area estimates? How would quantify the uncertainty in a glacier area estimate?

A) should all be similarB) Differences may be caused by snow cover and shadowingC) Differences may be caused by debris cover

Additional information:- in situ measurements - DEM for surface slopes- Multispectral band composite image (e.g. Landsat 543)- Velocity map to show which debris-covered parts are flowing

2. Electromagnetic SpectrumBelow is a schematic of the electromagnetic spectrum. For each of the categories in the table, describe possible cryosphere satellites and applications (you should be able to come up with ~3 applications for each wavelength). Underline one application for each wavelength; for that application, describe some advantages and disadvantages of using this sensor.

Wavelength

Satellite/Sensor

Applications

Advantages

Disadvantages

Visible

Historical photosLandsatMODISASTERSentinel-2

extent/mappingStructuresDEMvelocity

High res. No images incloud, night, or winter

Thermal Infrared

LandsatThermal cams

Microwave

SSMISMAP

Radar

Sentinel-1TerraSarXRadarsatERS 1/2

3. Structural MappingThe following two images show Byrd Glacier, Antarctica passing through the Transantarctic Mountains and entering the western margin of the Ross Ice Shelf. The first image (a) is an optical image acquired by Canada’s RADARSAT satellite.

Identify and highlight glaciological structures that you can identify on either image. What differences are due to sensor type?

A.

B.

Shear zones are much more defined in SAR imagesBuried crevasses are visible in SAR image (radar penetration intosnow)

4. Feature tracking for ice velocityPart of the experimental design of a project to measure glacier velocities by feature tracking requires choosing satellite imagery at an appropriate time interval, given a sensor’s ground range resolution and the expected ice speed. Complete the following tableto suggest appropriate time intervals in days for a robust velocity estimate, given different range resolutions and maximum glacier velocities.

Ground range resolution (m)Glacier velocity

(m/yr)3 m 15 m 30 m

50 m/yr23 days 115 days 250 days

300 m/yr4 days 18 days 37 days

2000 m/yr1 day 3-4 days 7 days