Building a Record of Surface Elevations of the Continental Ice Sheets from Satellite Radar Altimetry.
Anita C. Brenner(1) , John P. DiMarzio(2) , and H. Jay Zwally(3)
10210 Greenbelt Road,
Lanham, MD 20706,
(2) SGT, Code 614, Greenbelt, MD 20771, United States
(3) NASA, Code 614, Greenbelt, MD 20771, United States
Obtaining surface elevations over the continental ice sheets from satellite radar altimetry includes special challenges caused by the specific nature of the ice sheet surfaces in contrast to ocean surfaces. Special algorithms are required to account for the surface slopes and undulations, variations in surface reflection, and penetration of the signal into the snow surface. This presentation addresses these unique challenges and how we have overcome them to create a consistent record of ice sheet elevations from satellite radar altimetry. Specifically this will address the effect of the slope-induced error and our methodology for correcting the measurement; the effect of penetration and sub-surface volume scattering, the evolution of waveform shape fitting and retracking algorithms to determine the location of the surface return, and inter-mission biases calculated using both the ERS-1 and 2 tandem mission data and ICESat time-coincident laser altimeter measurements. Using consistent methodologies, NASA/GSFC has built a database including all ice sheet elevations retrieved from radar altimeters on Seasat, Geosat, ERS-1, ERS-2, and Envisat.