Exploring the atmospheres of the Giant Planets with James Webb

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The James Webb Space Telescope (JWST), scheduled for launch near the start of this PhD programme, is set to revolutionise our understanding of planetary atmospheres in this Solar System and beyond. Its 6.5-m diameter shielded mirror, combined with state-of-the-art infrared instrumentation, will provide exquisite observations of Solar System targets. Researchers at the University of Leicester were directly involved in the development of the MIRI instrument (5-30 micron spectroscopy in the mid-infrared), and Leicester planetary scientists have unique access to guaranteed-time observations of all four giant planets, to be acquired during the first year of operations (2021-22). The PhD candidate would be welcomed to a team of planetary atmospheres researchers at Leicester, to be trained in inversions of infrared spectroscopy to extract useful information on temperatures, chemical distributions, clouds, and atmospheric dynamics. The student will use a well-developed suite of radiative transfer and spectral inversion tools (known as NEMESIS) to compare previous spacecraft observations of Jupiter and Saturn to the highly-anticipated new data from JWST. The spatial distributions of gases will allow the student freedom to pursue a variety of scientific questions: (i) the ratios of key elemental abundances and isotope ratios to constrain planetary origins; (ii) the use of condensable volatiles (like ammonia) and disequilibrium species (like phosphine) to track changes in atmospheric dynamics (e.g., belts and zones, and large-scale structures like Jupiter's Great Red Spot and Saturn's polar hexagon); and (iii) the coupling of jovian weather with the chemically-rich middle atmospheres of the giant planets. Through these studies, the student will gain skills in processing and manipulating spacecraft data, extensive software development, and will have the opportunity to engage with the wider community of planetary observers across the globe. JWST observations will be supplemented by a campaign of ground-based supporting observations from world-leading facilities (e.g., observatories in Chile and Hawaii). Given the risks involved with the JWST mission, this studentship can still be undertaken with existing spacecraft data (primarily from Cassini and Juno), supplemented by our ongoing programme of ground-based planetary astronomy.With Leicester's current involvement in Juno and JWST, and future involvement in the Jupiter Icy Moons Explorer (JUICE), this Planetary Science PhD project offers the potential for exciting new discoveries on the giant planets. Successful PhD candidates would have some prior background in coding, as they will be using Fortran, IDL, and Python-based packages on Leicester's High-Performance Computing facility. Some prior knowledge of planetary atmospheric science and radiative transfer is desirable.