ANALYSIS OF SATELLITE-ALTIMETER HEIGHT MEASUREMENTS ABOVE CONTINENTALICE SHEETS

In order to estimate the accuracy of altimetric height measurements ov er ice sheets, an altimeter wave-form simulator has been developed, an d different tracking methods have been tested. A large range of surfac e features, including large-scale and medium-scale features and micro- roughness have been taken into account for modeling of either surface- or volume-scattering. A large set of parameters affects the trailing edge of the radar wave form, so that re-tracking algorithms based on t he detection of its leading edge provide better retrievals of the surf ace height than those based on the analysis of the whole wave form. A volume component is clearly present in the radar wave forms; its effec t on the leading edge depends mostly on the snow grain-size (and there fore on the snow temperature) and on the pointing angle. However, on a verage, the induced error on the snow-surface height estimation should only be around 25 cm.