Observations of a Stationary Mid-Latitude Cloud System on Titan

TL;DR

This study reports a long-lasting, localized mid-latitude cloud system on Titan observed over several days, combining ground-based and spacecraft data to analyze its altitude, opacity, and potential formation mechanisms.

Contribution

It provides detailed observations of a stationary cloud system on Titan, highlighting its persistence and raising questions about mesoscale circulation effects.

Findings

Clouds observed from 13 to 37 km altitude.

Cloud system remained localized for at least 34 hours.

Short-term cloud evolution consistent with previous studies.

Abstract

We report the observation of a cloud system on Titan that remained localized near 40S latitude and 60W longitude for at least 34 hours. Ground-based observations obtained with the SINFONI imaging spectrograph at the Very Large Telescope over 4 consecutive nights recorded the lifetime and altitude of the unresolved cloud system. Concomitant measurements made by Cassini/VIMS over 3 hours resolved changes in the altitude and opacity of individual regions within the system during this time. Clouds are measured from 13 to 37 km altitude with optical depths per pixel ranging from $\tau$=0.13 to 7. Short timescale rise times are consistent with previous measurements of the evolution of mid-latitude clouds; however the long timescale localization of the cloud structure is unexplained. We speculate about the role of meso-scale circulation in relation to cloud formation.