Fundamental Fluid Processes in Climate, Stellar and Planetary Modeling

What will the Earth’s atmosphere and oceans look like at the end of the century? What are the fates of the stars and planets observed in unprecedented detail with recent space missions? These questions are more closely related than they may seem. While there are very different physical conditions in the Earth’s atmosphere, oceans, stellar interiors, sub-surface oceans of icy satellites and liquid-metal planetary cores, the flows in each system are determined by the same Navier-Stokes equations. The wide range spatial and temporal scales at play in planets and stars prevents us from computing accurate solutions to these equations across all relevant length and timescales. Instead, state of the art computational methods solve the fundamental equations only on large spatial scales, for slow dynamics; then extra terms — parameterizations — are added to the equations to account for the neglected effects. The accuracy and predictive power of these simulations is determined by their underlying parameterizations. While the physical processes at play in climatology, astrophysics and planetology are similar, each community has developed its own parameterizations.

By bringing together specialists in atmospheric, oceanic, astrophysics and planetary communities, this project aims to determine the governing principles behind physical processes common across these fields, and then apply these principles to improve parameterizations for global evolution models. We aim to develop new physics-based parameterizations, new techniques for interpreting observational data and robust predictions of new phenomena. Combining theoretical, numerical and experimental approaches, this proposal targets three physical processes which have major impacts on climate, planets and stars: (i) the interplay between horizontal and vertical transport, (ii) wave interactions with turbulence and (iii) nonlinear wave transport.

Daniel Lecoanet is an assistant professor in the Department of Engineering Sciences & Applied Mathematics and a faculty member of the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) at Northwestern University. An expert in stellar astrophysics, he has worked extensively on convection and internal waves in stars. He is a core developer for the open-source spectral code Dedalus. He has published work on convection in planetary cores and in the Earth’s atmosphere, and he has organized interdisciplinary conferences and schools on fluid dynamics in astrophysics and geophysics.

Michael Le Bars is a CNRS senior researcher working at the Institute de Recherche sur les Phènoménes Hors Équilibre (IRPHÉ), where he is head of the “Nature, environment and universe” group. He uses laboratory experiments, together with theory and numerical simulations, to understand fundamental fluid processes involving rotation, stratification and convection. He is an expert in planetary science and has studied instabilities driven by tides, libration, and precession; lunar and planetary dynamos; Jupiter’s Great Red Spot and jets; and wave-mean flow interactions. He has led several interdisciplinary projects (including the ERC Consolidator project FLUDYCO) and has organized many conferences and schools on the field of Geophysical and Astrophysical Fluid Dynamics.

Stefan Llewellyn Smith is a professor in the Department of Mechanical and Aerospace Engineering and Scripps Institution of Oceanography at the University of California, San Diego, and a faculty member at the interdisciplinary Woods Hole Geophysical Fluid Dynamics summer program. His research interests are in fluid dynamics, from physical oceanography through vortex dynamics to small-scale flows, and in applied mathematics with a focus on scattering and applied complex analysis. He has a record of interdisciplinary research and funding, including collaborations with plant scientists, numerical analysts and geophysicists. His previous work includes tidal conversion, as well as the scattering of waves by vorticity and convection. He has co-organized international meetings in vortex dynamics and workshops, including the three-month program “Complex analysis and techniques”” at the Isaac Newton Institute in Cambridge.

Jerome Noir is a senior scientist in the Department of Earth Sciences at ETH Zurich and is the head of the FLOWLab experimental facility devoted to planetary hydro- and magneto-dynamics experiments. Through coupled experimental, numerical and theoretical investigations, his work focuses on linear and turbulent flows in planetary science. He has studied wave transport of angular momentum in planetary cores, precession-driven energy dissipation in the Lunar core, and the effect of topography on angular momentum and convective flows in planetary cores and subsurface oceans. He is co-investigator of an interdisciplinary investigation on Mars’ interior at ETHZ, co-author of a book on planetary shape, rotation and tides, and collaborates on geothermal energy and biomedical investigations. He has organized several international conferences and contributed to summer schools.

Tiffany Shaw is a professor in the Department of the Geophysical Sciences at the University of Chicago and a faculty member at the interdisciplinary Woods Hole Geophysical Fluid Dynamics summer program. She is an expert in geophysical fluid dynamics and climate physics. Her previous work includes the leading order control of moist physics for the atmospheric circulation under climate change, as well as energetic regimes in Earth’s climate. Shaw has a track record of cross disciplinary work, e.g., examining hydrological cycle regimes in planetary science, examining energetic regimes in paleoclimate and deriving mixing bounds in applied mathematics.

William R. Young is a distinguished professor of oceanography at the Scripps Institution of Oceanography, which is a department of the University of California, San Diego, and he is a member of the National Academy of Sciences. The focus of his research is the application of fluid mechanics and mathematics to oceanography and allied fields such as meteorology and planetary atmospheres. His previous work includes horizontal convection, near-inertial wave propagation and the interaction of tides with ocean bathymetry. Young has a track record of cross disciplinary work, e.g., most recently in proposing a mechanism for the origin of polar vortex crystals in the atmosphere of Jupiter.