SAR Interferometer Radar Altimeter (SIRAL)

SIRAL, the SAR Interferometer Radar Altimeter, is the Ku-band radar altimeter flown on CryoSat-2.^[1][2][3] It operates at 13.575 GHz, with WMO listing a 350 MHz bandwidth, and provides CryoSat-2 with a single-frequency radar-altimetry measurement system.^[1][2][3] SIRAL supports low-resolution nadir altimetry, SAR mode, and SAR interferometric mode using two cross-track-aligned antennas.^[1][2] Those modes let CryoSat-2 measure ice-sheet elevation and sea-ice freeboard while also supporting ocean dynamic topography, significant wave height, and wind speed over sea.^[1][2] Radar altimetry is demonstrated through SIRAL's CryoSat-2 service record.^[1]