Radar ice sounding allows for the retrieval of ice depth and provides information on ba-sal topography, basal conditions, flow, and layering. In the prospect of a possible future satellite ice sounding mission, surface clutters are expected to severely hamper measurement of radar ech-oes from the depth due to the unfavourable observation geometry. Synthetic aperture radar (SAR) processing enables to attenuate surface clutters in the forward and backward directions, but not in the across-track directions. Thus, additional across-track clutter cancellation is a crucial step for extracting weaker subsurface radar echoes. ESA’s P-band POLarimetric Airborne Radar Ice Sounder (POLARIS), recently upgraded with a larger antenna of 4 m length, enables simultaneous reception of up to 4 sub-aperture channels in across-track. Laboratory of Electromagnetics and Acoustics of Swiss Fed. Institute of Tech., Lausanne, developed and built the radiator-elements of the enhanced POLARIS. Several datasets were acquired in the multi-channel configuration during the Feb. 2011 campaign over East Antarctica. The POLARIS instrument will be briefly introduced, followed by an overview of the sounding campaign. Finally, different surface clutter suppression approaches, based on topographic data, are presented and compared. Clutter rejection performance is quantified through comparison with original data.