PAOC Colloquium: Raymond T. Pierrehumbert (University of Oxford)
Atmospheric dynamics of tide-locked exoplanets
A large proportion of the exoplanets discovered so far are in orbits sufficiently close to their host stars that tidal stresses are sufficiently strong that the spin state of planet will become tide-locked to the star on a time scale short compared to the age of the system. This includes all habitable-zone planets orbiting M stars, as well as all lava planets orbiting more massive main-sequence stars. Such planets have a permanent dayside and a permanent nightside, leading to a range of novel atmospheric circulations which have observable consequences in terms of the optical or infrared phase curves of the planets. In this talk, I will discuss the fundamental geophysical fluid dynamics underpinning our understanding of the atmospheric circulation and its ability to transport heat and chemical constituents. The theoretical framework draws on deep analogies with theories used to understand the climate of the Earth’s tropics, but also engages a number of novel phenomena including generation of super-rotating equatorial jets. In addition to having consequences for the interpretation of astronomical observations, these circulations can strongly effect the long term evolution of the atmosphere through their influence on such things as the runaway greenhouse threshold, volatile exchange with the crust, and sequestration of condensible substances on the nightside of the planet.
About the Speaker
Raymond T. Pierrehumbert is the Halley Professor of Physics at the University of Oxford. Previously, he was Louis Block Professor in Geophysical Sciences at the University of Chicago. He was a lead author on the Third Assessment Report of the IPCC (Intergovernmental Panel on Climate Change) and a co-author of the National Research Council [UK] report on abrupt climate change. He was awarded a John Simon Guggenheim Fellowship in 1996, which was used to launch collaborative work on the climate of early Mars with collaborators in Paris. He is a Fellow of the American Geophysical Union (AGU) and has been named Chevalier de l'Ordre des Palmes Académiques by the Republic of France. He was elected to the American Academy of Arts and Sciences in 2015.
Pierrehumbert's central research interest is how climate works as a system and developing idealized mathematical models to be used to address questions of climate science such as how the earth kept from freezing over. Current interests include climate of extrasolar planets.
About this Series
The PAOC Colloquium is a weekly interdisciplinary seminar series that brings together the whole PAOC community. Seminar topics include all research concerning the physics, chemistry, and biology of the atmospheres, oceans and climate, but also talks about e.g. societal impacts of climatic processes. The seminars generally take place on Monday from 12-1pm. Lunch is provided to encourage students and post-docs to meet with the speaker. Besides the seminar and lunch, individual meetings with professors, post-docs, and students are arranged.