Skip to main content
SearchLoginLogin or Signup

Investigating the evolution of Titan’s high altitude south polar HCN cloud

Presentation #208.04 in the session Titan I: Atmosphere (Oral Presentation)

Published onOct 23, 2023
Investigating the evolution of Titan’s high altitude south polar HCN cloud

Cassini’s 2012 detection of a giant HCN cloud 300 km above the south pole suggested much cooler temperatures than were expected for the fall stratosphere, but changes in Cassini’s orbit as well as the advancing winter darkness precluded detailed retrievals of temperature and vapor profiles until years later. We investigate the evolution of this cloud between 2012 and 2017 using TitanCARMA, a 1D cloud microphysical model, as well as imagery from Cassini’s ISS. We simulate the cloud by assuming it forms at 300 km around Ls = 30° and then descends until it reaches the lower stratosphere around Ls = 60°. Our simulations suggest that precipitation from this cloud could rapidly deplete the stratosphere of HCN vapor as HCN ice particles fall into the troposphere. Our simulations compare favorably to published observations of cloud properties, however these observations focus on the first Earth year after the cloud formed, with little published information regarding how the cloud evolved after 2013. We analyze ISS imagery between 2012 and 2017 to further constrain the horizontal and vertical extent of the cloud. These variables are vital to understanding the south polar cloud microphysics, dynamics, and radiative balance as well as the polar vortex dynamics.

No comments here