The formation and evolution of Titan's winter polar vortex

Nicholas A. Teanby*, Bruno Bézard, Sandrine Vinatier, Melody Sylvestre, Conor A. Nixon, Patrick G.J. Irwin, Remco J. De Kok, Simon B. Calcutt, F. Michael Flasar

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

25 Citations (Scopus)

Abstract

Saturn's largest moon Titan has a substantial nitrogen-methane atmosphere, with strong seasonal effects, including formation of winter polar vortices. Following Titan's 2009 northern spring equinox, peak solar heating moved to the northern hemisphere, initiating south-polar subsidence and winter polar vortex formation. Throughout 2010-2011, strengthening subsidence produced a mesospheric hot-spot and caused extreme enrichment of photochemically produced trace gases. However, in 2012 unexpected and rapid mesospheric cooling was observed. Here we show extreme trace gas enrichment within the polar vortex dramatically increases mesospheric long-wave radiative cooling efficiency, causing unusually cold temperatures 2-6 years post-equinox. The long time-frame to reach a stable vortex configuration results from the high infrared opacity of Titan's trace gases and the relatively long atmospheric radiative time constant. Winter polar hot-spots have been observed on other planets, but detection of post-equinox cooling is so far unique to Titan.

Original languageEnglish
Article number1586
JournalNature Communications
Volume8
Issue number1
DOIs
Publication statusPublished - 1 Dec 2017
Externally publishedYes

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