Titan's tropical storms in an evolving atmosphere

Caitlin Griffith, Christopher P. McKay, Francesca Ferri

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

The Huygens probe landed in a damp lake bed fed by fluvial channels, indicative of past rainfall. Such washes, interspersed with vast dunes, are typical of Titan's tropical landscape. Yet, Cassini-Huygens measurements reveal a highly stable tropical atmosphere devoid of deep convective storms, and the formation of washes in dune fields is not understood. Here we examine the effects of seasonal variations in humidity, surface heating, and dynamical forcing on the stability of Titan's troposphere. We find that during the probe landing, the middle troposphere was weakly unstable to convection, consistent with the tenuous cloud detected at 21 km. Yet the tropical atmosphere, at any season, is too stable to produce deep convective storms. Convection in the tropics remains weak and confined to altitudes below ∼30 km, unless the humidity is increased below 9 km altitude. Solar heating is insufficient to significantly humidify the tropical atmosphere. The large polar lakes are seasonably stable, and the methane column abundance measured by Huygens typical of the tropical atmosphere. Our study indicates the presence of distinct polar and equatorial climates. It also suggests that fluvial features in the tropics do not result from recent seasonal rainstorms, and thereby supports other origins such as geological seepage, cryovolcanism, or a wetter climate in the past.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume687
Issue number1
StatePublished - Nov 1 2008

Fingerprint

tropical storms
Titan
atmospheres
dunes
atmosphere
troposphere
tropical regions
climate
humidity
beds (geology)
rainstorms
convection
Huygens probe
probe
solar heating
seepage
dune field
landing
rainstorm
lake

Keywords

  • Analytical
  • Convection-methods
  • Individual (Titan)-radiative transfer
  • Planets and satellites

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Titan's tropical storms in an evolving atmosphere. / Griffith, Caitlin; McKay, Christopher P.; Ferri, Francesca.

In: Astrophysical Journal, Vol. 687, No. 1, 01.11.2008.

Research output: Contribution to journalArticle

Griffith, Caitlin ; McKay, Christopher P. ; Ferri, Francesca. / Titan's tropical storms in an evolving atmosphere. In: Astrophysical Journal. 2008 ; Vol. 687, No. 1.
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