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The novel SAR Interferometric mode(SARInM)of CryoSat-2 is designed to improve the accuracy,resolution and geolocation of height measurements over the steeper margins of ice sheets and ice caps.Over these areas,it employs the synthetic aperture radar(SAR)capability to reduce the size of the footprint.CryoSat-2 used the phase difference between its two antennas to estimate surface slope in the across-track direction and identify the point of closed approach directly.We used extensive coverage of Antarctica provided by the ICESat laser altimeter mission between 2003 and 2009 to assess the accuracy of SARInM data.We corrected for changes in elevations due to the interval between the acquisition of the ICESat and CryoSat-2 data(from July 2010 and December 2013).Two methods were used:(1)the ICESat point was compared with a DEM derived from CryoSat-2 data(Point-to-DEM; PtoDEM),and(2)the ICESat point was compared with a CryoSat-2 point directly(Point-to-Point; PtoP).