Surface roughness of Titan's hydrocarbon seas

摘要

We derive fields of solutions for the surface properties (roughness and permittivity) of the liquid hydrocarbon bodies Ligeia, Kraken and Punga Mare on Titan by applying the Radar Statistical Reconnaissance (RSR) technique to the Cassini RADAR observations in altimeter mode during the northern early summer. At the time of observation, Kraken and Ligeia were confined within root-mean-square heights of 1.5-2.5 mm (similar to wave heights of 6-10 mm), correlation lengths of 45-115 mm, and corresponding to effective slopes of 1.1-2.4 degrees. The latter extends up to 3.6-4.9 degrees if the rougher Punga is included. The lower bound of those ranges has to be considered if the composition of the seas is methane-dominant. These are the first measurements to simultaneously constrain both the vertical and horizontal roughness parameters of Titan's seas from the same observations. Our results are representative for the global properties of the sea-scaled portion of the studied tracks and suggest that quiet surfaces are a dominant trend over the seas during the northern early summer. Fields of rougher textures, if existent, might develop mainly over local patches and/or might not be sustained over significant periods of time. (C) 2017 The Author(s). Published by Elsevier B.V.