[IGPP Everyone] [EPSS Everyone] Planetary Science Seminar: TODAY at NOON

[Kevin McKeegan]

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*PLANETARY SCIENCE SEMINAR*

*Thursday, April 26*

*noon in Slichter 3853*

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*Sean Faulk and Kynan Hughson*

*Dept. of Earth, Planetary, and Space Sciences*

*UCLA*



*Sean Faulk:  "**Surface-atmosphere connections on Titan"*

   Titan harbors a rich hydroclimate with geomorphological evidence of
surface runoff, subsurface reservoirs, and sediment transport by intense
rainstorms. Regional patterns in these surface features suggest
corresponding regional climatic influences, namely in the form of
precipitation from the atmosphere. A model coupling the atmosphere to a
surface hydrology scheme is therefore required to fully explore Titan’s
surface-atmosphere connections. Previous general circulation models (GCMs)
of Titan have successfully reproduced Titan’s climate but have neglected
basic representations of surface hydrology. I will present a new Titan GCM
that includes simple parameterizations of surface and subsurface flow,
infiltration, and groundwater evaporation, and discuss the resulting
large-scale climate dynamics. The model promotes poleward methane transport
by surface/subsurface flows into saturated high-latitude lowlands and
equatorward methane transport by the atmosphere into unsaturated
low-latitude highlands. Infiltration into unsaturated soils then dries the
lower latitudes. The model therefore reproduces Titan’s observed equatorial
desert and polar wetlands regions but within a more physically consistent
framework than past GCMs.



* Kynan Hughson: **"Will it bend? Probing the mechanical properties of the
shallow subsurface of Ceres from fractured terrains in its Nar Sulcus
region."*

   Nar Sulcus is a unique geomorphic terrain located in the southwest
quadrant of Yalode crater on Ceres’ southern hemisphere. Geological mapping
of the fractured terrain revealed that it contains two sets of mutually
perpendicular fractures that we interpret to be low angle normal faults.  We
test the hypothesis that the topography and morphology of the Nar Sulcus
normal faults are controlled primarily by a thin ice-rich elastic layer. We
do this by mapping the structures in Nar Sulcus from Dawn spacecraft
images, comparing their profiles to a single layer flexural-cantilever
model for normal faulting similar to the one developed by Kusznir et al.
(1991), and analyzing their displacement:length ratios using a method
similar to the technique described in Cowie and Scholz (1992). This
analysis, which is similar to the one conducted on the europan ice shell by
Nimmo and Schenk (2006), estimates the elastic thickness and remote stress
acting on the faults at Nar Sulcus.





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Kevin D. McKeegan
Professor of Cosmochemistry & Geochemistry
Dept. of Earth, Planetary, and Space Sciences
UCLA
Los Angeles, CA 90095-1567
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mckeegan at epss.ucla.edu
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