Geostationary atmospheric sounding1 by formation flight aperture synthesis

This paper introduces a multi-satellite approach to passive microwave interferometric radiometry applied to geostationary atmospheric sounding at 53 GHz. The concept applies satellite formation flight to the currently operational interferometric techniques to extend the achievable microwave aperture sizes, leading to unprecedented spatial resolution for microwave radiometers. The presented configurations are capable of synthesising 14.4 m aperture and larger using SMOS-sized satellites, and spatial resolution better than 16.7 km at 53 GHz from the geostationary orbit. Two instrument concepts are proposed: Single-Element Companion concept and Array Duplicate concept, both of which are scalable, where the achievable spatial resolution is extendible and constrained only by the number of satellites in the constellation. The performance of both concepts are simulated, and the results show that the interferometer is highly sensitive to uncertainties in inter-satellite position measurements, where measurement errors as small as 6 mm result in 6.3 K root mean square error in radiometric accuracy.