Microwave Imaging Radiometers by Aperture Synthesis Performance Simulator (Part 2): Instrument Modeling, Calibration, and Image Reconstruction Algorithms

The Synthetic Aperture Interferometric Radiometer Performance Simulator (SAIRPS) has been a three-year project sponsored by the European Space Agency (ESA) to develop a completely generic end-to-end performance simulator of arbitrary synthetic aperture interferometric radiometers. In a companion manuscript (Part I), the Radiative Transfer Module used to generate synthetic fully polarimetric brightness temperatures from 1 to 100 GHz, including land and ocean covers, as well as the atmosphere, is described in detail. In this manuscript (Part II), the instrument model, the calibration procedure, and the imaging algorithms are described. The instrument model includes the simulation of the array topology in terms of the number of antenna elements, the time-dependent position and orientation, and the arbitrary receivers’ topology which can be modified from a very generic one by connecting and disconnecting subsystems. All the parameters can be, one by one, defined either by mathematical functions or by input data files, including the frequency and temperature dependence. Generic calibration algorithms including an external point source, the flat target transformation, and the two-level correlated noise injection are described. Finally, different image reconstruction algorithms suitable for arbitrary array topologies have also been implemented and tested. Simulation results have been validated and selected results are presented.