Robert L. Lysak

The 2015 Hannes Alfvén Medal is awarded to Robert L. Lysak for fundamental contributions to the theory of Alfvén waves that firmly established their importance in magnetosphere-ionosphere interactions.

Robert L. Lysak has led the community in understanding Alfvén waves. His research provides the theoretical underpinning required to understand the observed Alfvénic aurora and elucidates the role of Alfvén waves in particle acceleration on Earth and in planetary magnetospheres. There are numerous examples in support of the present significance of Alfvén waves in space plasmas, a number of them bearing his signature. For instance, the waves are being used to explain planetary magnetosphere-ionosphere (M-I) coupling phenomena, such as the Jovian aurora. Lysak recognised that Alfvén wave reflection from turbulent layers would modify the M-I coupling, and developed analytical and numerical models of the process. The latter has become one of the most cited and influential papers on M-I coupling. His highly cited model on the ‘feedback’ instability revolutionised our ideas of how the ionospheric conductivity influences auroral particle acceleration. He has also recognised the importance of including kinetic effects on Alfvén waves to understand propagation, energy transport and particle acceleration. These studies have had a strong impact on studies of particle acceleration in many regions including the aurora, reconnection and radiation belts.

Some of Lysak’s seminal contributions include his innovative dissertation research which contributed the seminal theory of stochastic auroral ion heating by large-amplitude coherent ion cyclotron waves. With collaborators he performed pioneering numerical simulations of dynamic magnetosphere-ionosphere coupling including turbulent transport. This early work demonstrated the role of Alfvén waves in establishing quasistatic auroral potential structures, and it leapfrogged the prevailing static equilibrium theories to bring evolutionary dynamics into the forefront. He also performed the first global simulations of ultralow frequency waves in dipole magnetic geometry. Follow-up research facilitated interpretations of in situ satellite measurements of magnetic fluctuations, serving as the foundation for subsequent numerical studies. He developed the theory of fast feedback instability leading to the intensification of so-called ionospheric Alfvén resonator modes. With co-workers, he pioneered the development of the kinetic theory of Alfvén waves with applications to auroral zone propagation. These works have had a significant impact on studies of particle acceleration in many regions including the aurora, reconnection and radiation belts.

Lysak has continued to refine and develop new sophisticated models of magnetohydrodynamic wave propagation in realistic geometries to understand processes such as standing waves, waves trapped in the ionospheric resonator, and energy flow from magnetotail tail reconnection regions. In addition to his research achievements, he has twice been editor of the Journal of Geophysical Research and has been an editor of numerous monographs and reports. He has inspired and nurtured a cohort of young scientists many of whom are now international figures in their own right.