Surface roughness on the Greenland ice sheet from airborne laser altimetry

High resolution airborne laser altimetry is used to determine the small-scale surface relief in central Greenland and estimate the contribution from spatial noise to stratigraphic records. The standard deviation of the surface roughness is 1.6 cm water equivalent, corresponding to a standard deviation of annual layer thickness of 2.3 cm we. This estimate agrees with an independent assessment of the spatial variability (2.5 cm we) based on nine shallow ice cores. The agreement suggests that the statistical nature of the surface in central Greenland remains unchanged throughout the year. By conducting airborne altimetry around proposed drilling sites, the expected noise level in the core can be evaluated and sites selected where this level is lowest.