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National Aeronautics and Space Administration

Goddard Space Flight Center

ALT

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Data Processing

Data Processing

To calculate precise ice surface elevations and changes in elevation, the altimeter range measurements need to be referenced to a common datum and corrected for tracker misalignment of the waveform due to inter-pulse variations, atmospheric delays, solid earth and ocean tides, and slope-induced errors. The corrected altimeter range measurement is then subtracted from a precision orbit to calculate a corrected surface height. The follwing table shows the corrections, in order of their magnitude, used in the data processing flow:

Correction Name Description Magnitude (m) Manner applied to surface height
Slope Correction Corrects for slope-induced errors. 0 to 150 (-)
Retracking Corrects for tracker lag. -15 to 15 (-)
Tropospheric Refraction Corrects for signal delay due to pressure variations and water vapor in the troposphere. 1.5 to 2.5 (+)
Ionospheric Refraction Corrects for signal delay due to charged particles in the ionosphere. .02 to .10 (+)
Tides (ocean and solid earth) Removes earth and ocean dynamics. -3 to 3 (-)