Universität zu Köln

Dott, Anne-Cathrine ORCID: 0009-0002-8605-639X (2025). Modeling the Spatiotemporal Surface Temperature Variations of Io and Europa: Io`s SO2 Sublimation Atmosphere and Constraints on the Moons` Polar Heat Fluxes. PhD thesis, Universität zu Köln.

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Abstract

Io is the innermost of Jupiter's four Galilean moons and the most volcanically active body in our Solar System. It has a SO$_2$ atmosphere with column densities on the order of $\sim$$10^{16}$ cm$^{-2}$. The volcanic ejecta cover Io's surface with yellowish SO$_2$ surface frost. The gas injection as well as the sublimation of the surface frost are considered to be the main causes of Io's atmosphere. However, what controls the spatial and temporal structure of Io's atmosphere and to what proportion the atmosphere is driven by volcanoes or sublimation, is a question with a considerable history. We develop a time dependent surface temperature model including thermal inertia and the exact celestial geometry to model the radiation driven global structure and temporal evolution of Io's atmosphere. We show that many observations can be explained by assuming a purely sublimation driven atmosphere and that the SO$_2$ column density not only depends on the latitude, but also has a diurnal, seasonal and longitudinal variation. In addition we are able to estimate Io's polar heat fluxes, that are neccesary to explain the moon's anomalously warm poles. The second-innermost Galilean moon Europa harbours a subsurface water ocean and is one of the most promising candidates for extraterrestrial life. In our study we use our radiative thermal transport model expanded by a Bond albedo map to investigate Europa's short and large scale spatiotemporal surface temperature variations that are observed to be not affected by the Eclipse by Jupiter but local albedo variations. It provides insights into the heat transport mechanisms on Europa and offers a framework for future studies on, e.g., spacecraft data from JUICE and Europa Clipper. Additionally, the estimation of Europa’s polar heat fluxes provides an important basis for tidal heating models and the estimation of Europa’s ice shell thickness.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Dott, Anne-Cathrine anne-cathrine.dott@uni-koeln.de https://orcid.org/0009-0002-8605-639X UNSPECIFIED
URN:	urn:nbn:de:hbz:38-790710
Date:	2025
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Geosciences > Institute for Geophysics and Meteorology
Subjects:	Earth sciences
Uncontrolled Keywords:	Keywords Language Numerical modeling using a thermal model including thermal inertia to model Io's surface temperature. UNSPECIFIED Investigation of spatiotemporal variations of Io's sublimation atmosphere and estimate on the moon's polar heat flux. UNSPECIFIED Modeling the surface temperature variations of Europa using a Bond albedo map and constraints on the polar heat fluxes. UNSPECIFIED
Date of oral exam:	30 September 2025
Referee:	Name Academic Title Roth, Lorenz Prof. Dr. Tezkan, Bülent Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/79071