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| Titel |
Titan's emergence from winter |
| VerfasserIn |
F. Michael Flasar, Richard Achterberg, Donald Jennings, Paul Schinder |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048899
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| Zusammenfassung |
| We summarize the changes in Titan’s thermal structure derived from Cassini CIRS and
radio-occultation data during the transition from winter to early spring. Titan’s surface, and
middle atmosphere show noticeable seasonal change, whereas that in most of the troposphere
is muted. This can be understood in terms of the relatively small radiative relaxation
time in the middle atmosphere and much larger time scale in the troposphere. The
surface exhibits seasonal change because the heat capacity in an annual skin depth
is much smaller than that in the lowest scale height of the troposphere. Surface
temperatures rise ~1 K at mid and high latitudes in the winter northern hemisphere and
cool in the southern hemisphere. Changes in in the middle atmosphere are more
complicated. Temperatures in the middle stratosphere (~1 mbar) increase by a few
kelvin at mid northern latitudes, but those at high latitudes first increase as that
region moves out of winter shadow, and then decrease. This probably results from
the combined effect of increased solar heating as the sun moves higher in the sky
and the decreased adiabatic warming as the sinking motions associated with the
cross-equatorial meridional cell weaken. Consistent with this interpretation, the warm
temperatures observed higher up at the winter polar stratopause cool significantly. |
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