Coupling convectively driven atmospheric circulation to surface rotation: Evidence for active methane weather in the observed spin rate drift of Titan

Authors: Jonathan L. Mitchell

(Submitted on 30 Jul 2008)

Abstract: A large drift in the rotation rate of Titan observed by Cassini provided the first evidence of a subsurface ocean isolating the massive core from the icy crust. Seasonal exchange of angular momentum between the surface and atmosphere accounts for the magnitude of the effect, but observations lag the expected signal by a few years.

We argue this time lag is due to the presence of an active methane weather cycle in the atmosphere. An analytic model of the seasonal cycle of atmospheric angular momentum is developed and compared to time-dependent simulations of Titan's atmosphere with and without methane thermodynamics. The disappearance of clouds at the summer pole suggests the drift rate has already switched direction, signaling the change in season from solstice to equinox.

Comments: 16 pages, submitted to ApJ

Subjects: Astrophysics (astro-ph); Space Physics (physics.space-ph)

Cite as: arXiv:0807.4778v1 [astro-ph]

Submission history

From: Jonathan Mitchell [view email]

[v1] Wed, 30 Jul 2008 04:00:12 GMT (109kb)

http://arxiv.org/abs/0807.4778