Shocks are some of the oldest known, most intensely studied space plasma phenomena. They are implicated in the production of solar energetic particles and galactic cosmic rays, both important for space weather. Yet questions remain about how they operate. It is unclear why particle acceleration at shocks is observed to be far more effective than can be explained by modern shock theories. Also, computer simulations have revealed that a variety of nonlinear, transient structures are very common ahead of shocks and thus need to be incorporated into our theories. But what tangible information about these ethereal and often distant phenomena can we base such theories on? Enter Terry Liu’s thesis. With originality and independence, Terry used Earth’s bow shock as an ideal laboratory to study foreshock transients and particle acceleration in generalized shock settings. In eight highly cited AGU and Science Advances publications, he showed how foreshock transients form, grow, evolve, create their own shocks, interact with the parent shock, and accelerate ions and electrons in a highly dynamical setting. He used comprehensive, in situ, multispacecraft data analysis, aided by powerful analytical models, and comparisons with hybrid simulations. His work has turned foreshock transients from an intellectual curiosity to a required element of any modern-day shock acceleration model.

—Vassilis Angelopoulos, Department of Earth, Planetary and Space Sciences, University of California, Los Angeles

Presentation Title: Observations of a New Foreshock Region Upstream of a Foreshock Bubble’s Shock

Event: 2016 Fall Meeting

Awarding Section: Space Physics and Aeronomy