Combined use of Cassini Radar active and passive measurements to characterize Titan morphology

Abstract

This paper focuses on the Titan surface parameters retrieval with emphasis on a combination of passive and active microwave measurements from Cassini spacecraft on the areas characterized by large liquid surfaces and neighboring land areas. The methodology consists of a combination of direct modeling and inversion algorithms. First, these surfaces have been described by means of a double layer model which considers an upper liquid hydrocarbons layer and a lower layer compatible with the radar response of the neighboring areas. This model is introduced into a Bayesian framework for the purpose of inferring the likely ranges of some parameters, in particular the optical thickness of the hypothesized liquid hydrocarbons layer and the wind speed. Second, the optical thickness information is used as an input to a forward radiative transfer model calculation to obtain simulated brightness temperatures. Comparison of the observed and computed brightness temperatures allows addressing the consistency of the observations from the two instruments.