Tracking Short-term Variations in the Haze Distribution of Titan's Atmosphere with SINFONI VLT

While it has long been known that Titan's haze and atmosphere are dynamic on seasonal timescales, recent results have revealed that they also exhibit significant subseasonal variations. Here, we report on observations of Titan acquired over an eight-month period between 2014 April and 2015 March with the Spectrograph for Integral Field Observations in the Near Infrared instrument on the Very Large Telescope using adaptive optics. These observations have an average five-day cadence, permitting interrogation of the short-period variability of Titan's atmosphere. Disk-resolved spectra in the H and K bands (1.4-2.4 mu m) were analyzed with the PyDISORT radiative transfer model to determine the spatial distribution and variation of stratospheric haze opacity over subseasonal timescales. We observed a uniform decrease in haze opacity at 20 degrees N and an increase in haze opacity at 250-300 degrees E and similar to 40 degrees N over the span of our observations. Globally, we found variations on the order of 5%-10% on timescales of weeks, as well as a steady, global increase in the amount of haze over timescales of months. The observed variations in haze opacity over the short timescales of our observations were of similar magnitude to long-period variations attributed to seasonal variation, suggesting rapid dynamical processes that may take part in the distribution of hazes in Titan's atmosphere.

Automated summary

Recent observations of Titan using near-infrared instruments have shown significant subseasonal variations in its atmosphere, with haze opacity decreasing in some regions and increasing in others over short time periods. These rapid changes suggest dynamic processes at play in the distribution of hazes in Titan's atmosphere, in addition to the known seasonal variations.