Universität zu Köln

Le Gall, A., Malaska, M. J., Lorenz, R. D., Janssen, M. A., Tokano, T., Hayes, A. G., Mastrogiuseppe, M., Lunine, J. I., Veyssiere, G., Encrenaz, P. and Karatekin, O. (2016). Composition, seasonal change, and bathymetry of Ligeia Mare, Titan, derived from its microwave thermal emission. J. Geophys. Res.-Planets, 121 (2). S. 233 - 252. WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 2169-9100

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Abstract

For the last decade, the passive radiometer incorporated in the Cassini RADAR has recorded the 2.2cm wavelength thermal emission from Titan's seas. In this paper, we analyze the radiometry observations collected from February 2007 to January 2015 over one of these seas, Ligeia Mare, with the goal of providing constraints on its composition, bathymetry, and dynamics. In light of the depth profile obtained by Mastrogiuseppe et al. (2014) and of a two-layer model, we find that the dielectric constant of the sea liquid is <1.8, and its loss tangent is 3.6-2.1+4.3x10-5. Both results point to a composition dominated by liquid methane rather than ethane. A high methane concentration suggests that Ligeia Mare is primarily fed by methane-rich precipitation and/or ethane has been removed from it (e.g., by crustal interaction). Our result on the dielectric constant of the seafloor is less constraining <mml:mfenced open=2.9-0.9+0.9, but we favor a scenario where the floor of Ligeia Mare is covered by a sludge of compacted and possibly nitrile-rich organic material formed by the deposition of photochemical haze or by rain washing of the nearby shores. We use these results to produce a low-resolution bathymetry map of the sea. We also estimate the temperature variation of the bulk sea between February 2007 and July 2013 to be <2K, which provides a constraint on its net evaporative cooling currently being explored in ocean circulation models. Lastly, we suggest a lag in the summer warming of the northern polar terrains.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Le Gall, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Malaska, M. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lorenz, R. D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Janssen, M. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tokano, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hayes, A. G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mastrogiuseppe, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lunine, J. I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Veyssiere, G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Encrenaz, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Karatekin, O. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-285124
DOI:	10.1002/2015JE004920
Journal or Publication Title:	J. Geophys. Res.-Planets
Volume:	121
Number:	2
Page Range:	S. 233 - 252
Date:	2016
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	2169-9100
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CHEMICAL-COMPOSITION; LIQUID ETHANE; CASSINI RADAR; SURFACE; LAKES; NITROGEN; METHANE; DISSOLUTION; SOLUBILITY; ATMOSPHERE Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/28512