Submillimeter Wave Instrument radiometry of the Jovian icy moons

Numerical simulation of the microwave thermal radiative transfer and Bayesian retrieval of the physical properties

¹ Max-Planck-Institut für Sonnensystemforschung Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
e-mail: ilyushin@mps.mpg.de
² Physical Faculty, Moscow State University, 119992 GSP-2 Lengory, Moscow, Russia
e-mail: ilyushin@phys.msu.ru
³ Institute of Radio-engineering and Electronics, ulitza Mokhovaya, 11/7 125009 Moscow, Russia

Received: 29 November 2019
Accepted: 6 October 2020

Abstract

Context. We address the issue of remote sensing of the surfaces of Galilean icy moons. We investigate the prospects for retrieval of the physical parameters of the surface of the Jovian icy moons from submillimeter wave radiometry data.

Aims. We show that the model parameters could not be completely retrieved from the polarized radiometry data, but some of their combinations can be effectively constrained.

Methods. The polarized radiative transfer in lossy porous ice was numerically simulated. A Bayesian maximum likelihood retrieval algorithm was developed and tested on the simulated data in a wide range of variation of the model parameters. The uncertainty of the retrievals was evaluated with the Cramer-Rao bounds. We established the combinations of model parameters that can be effectively constrained from the measured data.

Results. We reveal that the effective scatterer size can be reliably constrained for a range of values where the scattering asymmetry parameter uniquely depends on the wave parameter, and for relatively high values of the single scattering albedo, for which the scattering in the medium is significant. Similarly, the domains of reliable retrieval of the single scattering albedo and thermal skin depth are established.