SURFACE-ROUGHNESS ON THE GREENLAND ICE-SHEET FROM AIRBORNE LASER ALTIMETRY

High resolution airborne laser altimetry is used to determine the smal l-scale surface relief in central Greenland and estimate the contribut ion from spatial noise to stratigraphic records. The standard deviatio n of the surface roughness is 1.6 cm water equivalent, corresponding t o a standard deviation of annual layer thickness of 2.3 cm we. This es timate agrees with an independent assessment of the spatial variabilit y (2.5 cm we) based on nine shallow ice cores. The agreement suggests that the statistical nature of the surface in central Greenland remain s unchanged throughout the year. By conducting airborne altimetry arou nd proposed drilling sites, the expected noise level in the core can b e evaluated and sites Selected where this level is lowest.