I am a Professor of Planetary Physics at the University of Oxford in the Department of Physics, specifically the sub-department of Atmospheric, Oceanic, and Planetary Physics. I have over 30 years experience in remote sensing of planetary atmospheres from satellite observations, and more recently ground-based observations, and am the principal author or co-author of over 300 papers published in the open scientific literature. My main research interests are: 1) Radiative transfer modelling of the planetary atmospheres using thermal emission and scattering models; and 2) Development and application of multivariate retrieval methods, in particular the NEMESIS code. I was a member of the Galileo Near Infrared Mapping Spectrometer (NIMS) science team and a Co-Investigator of Cassini Composite Infrared Spectrometer (CIRS). I was also a Co-Investigator of the Visible Infrared Thermal Imaging Spectrometer (VIRTIS) on ESA ROSETTA and Venus Express missions, and was a Consultant Scientist to the Long Wave Spectrometer team of the Infrared Space Observatory.
I have been involved with several ground-based observation campaigns using UKIRT, Gemini and VLT and have taken a particular interest in monitoring seasonal changes in Uranus' cloud structure during and after its northern spring equinox in December 2007 and more recently as Uranus heads for its sorthern summer solstice in 2030. In 2018, I and my collaborators discovered hydrogen sulphide in the atmosphere of Uranus, which attached a lot of interest, with the work reported by NOIRLab and the BBC. Subsequently, we also reported the detection of hydrogen sulphide in the atmosphere of Neptune.
In 2022, I worked on a revised vertical structure of aerosols in the atmospheres of both Uranus and Neptune, for which a side product was an explanation for the different colours of Uranus and Neptune. I also led two papers in 2023 reporting observations of Neptune made with the MUSE Integral Field Unit specrometer at the Very Large Telescope in Chile in 2019. This resulted in the first ever ground-based detection of a dark spot in Neptune's atmosphere, but more importantly, the first ever measurement of the continuous visible reflectance spectrum of such spot. Most recently, I led a paper revisiting the colours of Uranus and Neptune and modelling the seasonal variations of Uranus's colour as it orbits the Sun.
In preparation for possible entry probe missions I have been working on simulating in situ observations that might be made of the atmospheres of Venus and Uranus, and in 2020 released two YouTube simulations for Uranus and Venus.
I also study the atmospheric spectra of Mars, Jupiter, and exoplanets. Please see my publications page for more details of this work.
You can also find links to my research, teaching and publications at my Physics Department Personal Page.
When I'm not researching, I am a physics tutor at St Anne's College, Oxford.