KaRIn on SWOT: Characteristics of Near-Nadir Ka-Band Interferometric SAR Imagery

The principal instrument of the NASA/CNES wideswath altimetry mission Surface Water and Ocean Topography (SWOT) is the Ka-band Radar Interferometer (KaRIn), a bistatic synthetic aperture radar (SAR) system operating on near-nadir swaths on both sides of the satellite track. There are limited reports on backscattering from natural surfaces at this short wavelength and particular observation geometry. Near-field backscattering measurements on water, as well as the first interferometric airborne SAR acquisitions at Ka-band covering the 0.6 degrees-3.9 degrees incidence range of KaRIn, were therefore conducted. The experimental results confirm expected characteristics of near-nadir Ka-band interferometric SAR imagery, such as strong water/land radiometric contrast (typically in the order of 10 dB) and very high interferometric coherence on water.