Dynamics of Titan's thermosphere
Dynamics of Titan's thermosphere
We estimate the wind speeds in Titan’s thermosphere by considering the various terms of the wind equation, without actually solving it, with a view to anticipating what might be observed by the Cassini spacecraft in 2004. The winds, which are driven by horizontal pressure gradients produced by solar heating, are controlled in the Earth’s thermosphere by ion-drag and coriolis force, but in Titan’s thermosphere they are mainly controlled by the nonlinear advection and curvature forces. Assuming a day–night temperature difference of 20 K, we find that Titan’s thermospheric wind speed is typically 60 m s-1. In contrast, the Earth’s thermospheric winds, of order 50 m s-1, do not equalize day and night temperatures. We speculate on other factors, such as the electrodynamics of Titan’s thermosphere and the tides due to Saturn.
51-58
Rishbeth, H.
fb69f152-f92f-4579-95b2-532898a077d1
Mendillo, M.
0b4e45c2-16ab-4130-aace-eaf6e3f6b561
Yelle, R.
b40713f4-6d42-4670-8fe0-31ac54a623e2
2000
Rishbeth, H.
fb69f152-f92f-4579-95b2-532898a077d1
Mendillo, M.
0b4e45c2-16ab-4130-aace-eaf6e3f6b561
Yelle, R.
b40713f4-6d42-4670-8fe0-31ac54a623e2
Abstract
We estimate the wind speeds in Titan’s thermosphere by considering the various terms of the wind equation, without actually solving it, with a view to anticipating what might be observed by the Cassini spacecraft in 2004. The winds, which are driven by horizontal pressure gradients produced by solar heating, are controlled in the Earth’s thermosphere by ion-drag and coriolis force, but in Titan’s thermosphere they are mainly controlled by the nonlinear advection and curvature forces. Assuming a day–night temperature difference of 20 K, we find that Titan’s thermospheric wind speed is typically 60 m s-1. In contrast, the Earth’s thermospheric winds, of order 50 m s-1, do not equalize day and night temperatures. We speculate on other factors, such as the electrodynamics of Titan’s thermosphere and the tides due to Saturn.
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Published date: 2000
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Local EPrints ID: 9179
URI: http://eprints.soton.ac.uk/id/eprint/9179
PURE UUID: a869f9b9-564a-48d6-9722-79e7d6cc7316
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Date deposited: 24 Sep 2004
Last modified: 15 Mar 2024 04:55
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Author:
H. Rishbeth
Author:
M. Mendillo
Author:
R. Yelle
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