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Ice Sheet Motion. Speckle tracking. InSAR. Feature Retracking. Day 1. 100 m. Day 24. Day 1 Day 24. Day 1 Day 24. 10 m. 10 m. Velocity measurement techniques. Speckle Retracking. Speckle Geometry. Range direction only. Preprocessing. Doppler Overlap.

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ice sheet motion

Ice Sheet Motion

Speckle tracking

velocity measurement techniques


Feature Retracking

Day 1

100 m

Day 24

Day 1 Day 24

Day 1 Day 24

10 m

10 m

Velocity measurement techniques

Speckle Retracking

doppler overlap
Doppler Overlap

(See if you can use the image data to compute doppler spectra)

azimuth corrections
Azimuth Corrections
  • Azimuth pixel spacing goes as prf as well as orbit height, terrain elevation, look angle and latitude. Consequently two slightly different orbits will have slightly different azimuth spacings given approximately by

For a purely vertical separation, corresponding to about 14 m in height, the azimuth

Displacement will change about 3 parts in 10^6. There will be an accumulating

Error such that after about 500 km, the azimuth will be incorrect by a measurable

.3 pixels.

coherence streaks
Coherence Streaks

An early incorrect idea

ionospheric streaks
Ionospheric Streaks
  • For C-band Radarsat, A SAR footprint is illuminated for about 0.5 sec. The satellite travels about 3.5 km.
  • If the integrated electron density changes along the line of sight, while the footprint is illuminated, then the phase history built from about 600 pulses will be corrupted
  • The consequence is incorrect azimuth placement.
  • The effect is smaller in the range direction.
  • Idea tested by
    • Comparing streak density with ionospheric activity
    • Simulations using a phase screen
    • Relationships to streak density and magnetic poles

Option 3 – only ascending descending range products.

Option 1 – azimuth offset, range phase; azimuth offset, range offsets; ascending descending range;

Plug Vr into Vf and differentiate along flow direction

We assume that several terms are small: change in look direction is small; changes in flow directions are small for large glaciers over 0-30 km, Large scale strain rates not effected by surface slope.