Spaceborne X-band synthetic aperture radars (SARs) represent a well-established tool for Earth remote sensing at very
high spatial resolution (order of meters). Until now, SAR has not been exploited for hydrological cycle modelling and
numerical weather forecast, however, there are scientific evidences that at X band and beyond: i) atmospheric
precipitation in liquid and ice phase affect SAR imagery and its intensity can be retrieved, ii) snow areal extent and mass
(water-equivalent) can be detected and estimated.
KydroSAT mission concept foresees a miniaturised fully-digital SAR at Ku and Ka band (KydroSAR), specifically
devoted to detecting and estimating atmospheric precipitation and surface snow; its baseline includes dual-polarization
capability, high orbit duty cycle (>75%), flexible ground resolution (5-150 m), and a large variable swath (50-150 km),
doubled with formation of two minisatellites both carrying a KydroSAR. Moreover, the mission concept foresees the
along-track convoy with the COSMO-SkyMed and SAOCOM SAR platforms, allowing the observation of the same
scene at L, X, Ku and Ka bands. The challenging requirements of this architecture require the development of new
technologies such as Digital Beam Forming and Direct Digital to RF Conversion.
In order to exploit the synergic approach of the KydroSAT convoy for precipitation, in this work we will simulate and
discuss the SAR response at X, Ku and Ka bands of the same scene, using the SAR forward model described in Mori et
al. (2017). Subsequently, an example retrieval of Snow Equivalent Water (SWE) by Ku-SAR will be given.