Heliospheric Turbulence: Recent Advances and an Overview of its Effects

Abstract

Turbulence in general is an unsolved problem, and relative to ordinary fluids, it is even more complex in plasma or magnetofluids (“MHD”).   In fluids, the usual scenario involves driving, cascade and dissipation.  In plasma models, one also deals with interaction between nonlinearities and oscillatory wave modes, as well as anisotropy and the presence of multiple ideal conserved quantities.  The solar wind is a major heliospheric ingredient that admits broadband MHD-like turbulence, having numerous far-reaching effects, ranging from heating of the corona and acceleration of the wind itself, to controlling the propagation of high energy solar energetic particles and galactic cosmic rays.   This lecture will present an overview of turbulence effects in the heliosphere and in particular, the solar wind. Examples from observations are provided in this lecture, corresponding to theoretical aspects of turbulence, which themselves are often revealed and understood by use of numerical simulations.   Topics covered include advances in understanding MHD and kinetic plasma cascade, issues in adaptation of classical turbulence theory to collisionless plasmas, small scale dissipative intermittency, heating, anisotropy of both variance and correlation types, space-time correlations, and the generation of very low frequency intermittency. 

Suggested Readings

[1] W H Matthaeus, Phys Plasmas, 28 (2021) 

[2] S. Oughton et al, Phil. Trans. Roy Soc A 373 (2015) 

[3] S. Oughton and W. H. Matthaeus, ApJ, 897 37 (2020) 

[4] M. Brodiano et al, ApJ 922, 240 (2021) 

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Short Bio

William H. Matthaeus, PhD is Martin A. Pomerantz Professor of Physics and Astronomy at the University of Delaware. He received his BA degree in Physics and Philosophy from the University of Pennsylvania in 1973, and a PhD from William and Mary in 1979. He was an NRC Postdoctoral Research Associate at Goddard Space Flight Center 1980-1982.  In 1983 he joined the faculty at the Bartol Research Institute at the University of Delaware.  He became Full Professor in 2005, was appointed Unidel Professor of Physics and Astronomy in 2016, and later, Martin A. Pomerantz Chair of Physics and Astronomy. He received the James B. Macelwane Award from the American Physical Society. In 2018 he received the Ruth Gall Prize sponsored by ALAGE, and in 2019 received the James Clerk Maxwell Prize in Plasma Physics from the APS. In 2020 Mahidol University in Thailand conferred him with an Honorary Doctorate and in 2024 he was selected as the Lorenz Lecturer by the American Geophysical Union. He is Fellow of the American Physical Society, the Institute of Physics, the American Geophysical Union, and the American Association for Advancement of Science. He is Director of the Delaware NASA Space Grant and the Delaware NASA EPSCoR program.  He is Co-investigator on a number of spacecraft missions, including Cluster/PEACE, the Magnetospheric Multiscale mission, the Parker Solar Probe ISOIS instruments, the Interstellar Mapping and Acceleration Probe, PUNCH and Helioswarm. He has organized the annual Arcetri Workshop on Plasma Astrophysics since 2006. He has authored 600+ publications having ~40,000 citations with H-factor 103 on Web of Science.    In 2025 he was elected Member of the US National Academy of Sciences.

Matthaeus studies turbulence theory, plasma physics, fluid mechanics, and statistical mechanics, with applications to solar wind and coronal phenomena and transport and energization of charged particles in plasmas. He employs analytical, computational and observational methods to study turbulence cascade and transport, which, along with the associated complex kinetic plasma physics response, lead to dissipation and heating.

Online Attendance

Information on remote participation can be requested by sending an e-mail to dn_sst@unitn.it