Polar motion of Titan forced by the atmosphere
In: Journal of Geophysical Research. American Geophysical Union: Richmond. ISSN 0148-0227; e-ISSN 2156-2202, more
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Titan;polar motion;atmosphere |
| Authors | | Top |
- Tokano, T.
- Van Hoolst, T., more
- Karatekin, O., more
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| Abstract |
Titan's atmosphere possesses an equatorial component of angular momentum, which can be transferred to the surface and can excite polar motion of Titan. The atmospheric excitation of Titan's polar motion is calculated using the wind and pressure data prediction from a general circulation model. The polar motion equation is solved considering Titan's triaxial shape and different hypothetical interior models. Titan's polar motion basically consists of a superposition of small diurnal wobbles and larger semiannual and annual wobbles caused by seasonal redistribution of wind and pressure pattern. If the entire interior of Titan is solid, the polar motion has total amplitudes of a few meters, but the diurnal and seasonal wobble may be intermingled due to preferential damping of the seasonal wobble by Saturn's gravitational torque. If instead there is a subsurface ocean underneath the crust, the wobble amplitude could be larger by an order of magnitude. If the crust is thin, a resonance between the seasonal and Chandler wobble further increases the polar motion amplitude and makes the polar motion path elliptical. The seasonal wobble of a crust lying on a subsurface ocean experiences damping by either gravitational and pressure torque or elastic torque, but the relative reduction of the polar motion amplitude by these torques is likely to be smaller than that of the length-of-day variations. |
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