Project Background
Titan is the largest moon of Saturn and is the only moon in our solar system with a substantial atmosphere, composed of nitrogen, methane and a host of trace organic species. In many ways Titan is a miniature version of Earth, but under much colder conditions and with an exotic atmospheric composition. Many atmospheric processes occurring on Earth have analogues on Titan, including polar vortices, large-scale atmospheric circulation, photochemistry, polar night radiative cooling, cloud formation, and rainstorms. For example, Titan's stratospheric organic hazes and trace gases play a similar role to Earth's ozone layer. Studying Titan's atmosphere is fascinating in its own right, but also provides a natural laboratory for probing fundamental atmospheric chemical and dynamical processes. These processes are also important for understanding Earth's atmosphere and those of many other planets in the Solar System and beyond.
Project Aims and Methods
This project will study dynamical and chemical processes in Titan stratosphere and mesosphere. In particular, extreme planetary-scale winds (jets) and mixing processes between polar and mid-latitude air masses. These processes control much of the large-scale seasonal changes occurring on Titan and are fundamental to understanding its climate. Atmospheric features will be studied using infra-red spectroscopic observations from orbiting spacecraft (Cassini), space telescopes (James Webb), and ground-based observatories (ALMA). There will also be opportunities to propose additional new telescope observations during the PhD. Spectra will be analysed using radiative transfer methods and inverse theory techniques to recover atmospheric properties that best fit observations and existing constraints. The derived physical and chemical atmospheric state can then be used to develop interpretations of atmospheric circulation, photochemistry, and seasonal evolution. Minor organic chemical species are particularly interesting as they act as tracers of atmospheric circulation and can be used to probe winds and air mixing. There will be opportunities for the student to guide the project direction, in particular during data analysis and interpretation or in proposing new observations.
Spacecraft data analysis will comprise the bulk of the project, led by the main supervisor (Dr Teanby). To help interpret observed atmospheric features, results will be compared to theoretical predictions and numerical planetary climate models adapted from studies of the Earth's atmosphere, which are currently under development by members of the supervisory team (Dr Seviour and Dr Mitchell). These observation-theory-model comparisons will allow more complete understanding of Titan's atmosphere and will potentially feed back into our understanding of fundamental climate physics. Results will also inform the next generation of space missions such at the Dragonfly nuclear-powered drone mission to Titan.