AltimetryHow it worksFrom pulse to measurements

Full deramp technique | Ocean waveforms | Ice waveforms | Land waveforms

3.1.2.3. Continental ice waveforms

a waveform over ice, and the parameters that can be extracted from it.
(Credits LEGOS/CNRS)

The echo waveform over ice enable to retreive several parameters:

• epoch at mid-height: this gives the time delay of the expected return of the radar pulse (estimated by the tracker algorithm), and thus the time the radar pulse took to travel the satellite-surface distance (or 'range') and back again.
• backscatter coefficient, sigma0.
• leading edge amplitude
• leading edge width: this is related to the penetration into the medium and the surface roughness of the target.
• trailing edge slope: this gives information on antenna mispointing, and also on the signal penetration into the medium.

All altimeter data for ice sheets must be post-processed to produce accurate surface elevation measurements. This post-processing is called 'retracking' and is required because the leading edge of the ice-sheet return waveform deviates from the on-board altimeter tracking gate, causing an error in the telemetered range measurement.