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Bad Ronald
2010-Dec-10, 01:21 AM
It seems in some places Titan's oceans are receding at a meter a year. Plus Titan`s methane seas seem to be near the poles & not so much near the equator.

What's the story with Titan's "hydrological" cycle & oceans?

Thoughts & ideas about this welcome.

baric
2010-Dec-10, 02:37 AM
Titan's standard surface temperature is actually quite close to the triple point of methane. Therefore, small seasonal changes in temperature can trigger larger-than-expected cycles involving methane.

John Jaksich
2010-Dec-12, 12:46 PM
It seems in some places Titan's oceans are receding at a meter a year. Plus Titan`s methane seas seem to be near the poles & not so much near the equator.

What's the story with Titan's "hydrological" cycle & oceans?

Thoughts & ideas about this welcome.


Titan is known to have seasons---but to the best of my knowledge there are no seas nor oceans to speak of but large bodies of hydrocarbon liquid--the bodies are known to ebb and flow somewhat--- (similar to a lake) and it is known that methane and ethane precipitate from the atmosphere. I will post my sources in subsequent post

John Jaksich
2010-Dec-12, 01:07 PM
If you have access to the following paper:


AN ESTIMATE OF THE CHEMICAL COMPOSITION OF TITANíS LAKES
Daniel Cordier, Olivier Mousis, Jonathan I. Lunine, Panayotis Lavvas, and Veronique Vuitton



It seems to be accepted to Icarus: here is a link to the preprint server:

http://arxiv.org/abs/0911.1860

There some discussion on the composition of Titan's lakes at the poles and at the equator.

John Jaksich
2010-Dec-12, 01:18 PM
In another paper---also on the pre-print server--there is some discussion on the weather cycle

Here is the abstract: (Title: Observations of a Stationary Mid-Latitude Cloud System on Titan

Authors: M. Adamkovics, J.W Barnes, M. Hartung, & I de Pater



Accepted for publication in Icarus, 10.1016/j.icarus.2010.03.006


arXiv:1003.2657v1 [astro-ph.EP] 12 Mar 2010
Abstract: We report the observation of a cloud system on Titan that remained localized
near 40◦ S latitude and 60◦ W longitude for at least 34 hours. Ground-based observations obtained
with the SINFONI imaging spectrograph at the Very Large Telescope over 4 consecutive nights
recorded the lifetime and altitude of the unresolved cloud system. Concomitant measurements
made by Cassini/VIMS over 3 hours resolved changes in the altitude and opacity of individual
regions within the system during this time. Clouds are measured from 13 to 37 km altitude with
optical depths per pixel ranging from τ =0.13 to 7. Short timescale rise times are consistent with
previous measurements of the evolution of mid-latitude clouds; however the long timescale local-
ization of the cloud structure is unexplained. We speculate about the role of meso-scale circulation
in relation to cloud formation



Let me know if this is hefpful.

John Jaksich
2010-Dec-12, 01:31 PM
Last post for now:


the following link seems to be the most extensive--of late---

http://arxiv.org/abs/0907.2255


Authors are the same as above. M. Adamkovics, J.W Barnes, M. Hartung, & I de Pater


Title:
Evidence for condensed-phase methane enhancement over Xanadu on Titan



Here is a snippet from the paper:



We present evidence for condensed phase methane precipitation near Xanadu using nine nights of observations from the SINFONI integral-field spectrograph at the Very Large Telescope and imaging analysis with empirical surface subtraction. Radiative transfer models are used to support the imaging technique by simulating the spectrometer datacubes and testing for variations in both the surface reflectivity spectrum and atmospheric opacity. We use the models and observations together to argue against artifacts that may arise in the image analysis. High phase angle observations from Cassini/VIMS are used to test against surface scattering artifacts that may be confused with sources of atmospheric opacity. Although changes in the surface reflectivity spectrum can reproduce observations from a particular viewing geometry on a given night, multiple observations are best modeled by condensed-phase methane opacity near the surface. These observations and modeling indicate that the condensed-phase methane opacity observed with this technique occurs predominantly near Xanadu and is most likely due to precipitation.



accepted for publication in Planetary and Space Science

baric
2010-Dec-12, 02:36 PM
Thank you very much for the links, John!