Amping It Up: Electric Currents in the Earth's Magnetosphere

Dr John Coxon, Department of Physics and Astronomy

John CoxonJohn Coxon completed his Master’s degree in Physics with Astrophysics at the University of Leicester in 2011, and in 2015, he completed his PhD here before going to the University of Southampton to take up a postdoctoral position. In addition to studying the Birkeland currents which comprise his thesis work, he is particularly interested in studying the way in which the solar wind drives phenomena that can affect us; both in the region of near-Earth space known as the magnetosphere, and on Earth itself. Alongside his academic work, he has won the STFC Public Engagement Large Award to construct and build a planeterrella in Southampton, and is keen to engage the public with auroral physics and space weather.


Earth’s magnetosphere is the region of space in which Earth’s magnetic field is the dominant part of the physics at work, and the solar wind interacts with Earth’s magnetic field at the edge of this region, known as the magnetopause. The magnetopause and Earth’s upper atmosphere are connected by the Birkeland currents, which are electrical currents flowing along magnetic field lines from the edge of the magnetosphere to the layer of Earth’s atmosphere known as the ionosphere. John’s research is focused on understanding how these currents react to driving by the solar wind, using a new method for measuring the Birkeland currents: AMPERE, which uses observations from the 66 satellites in the Iridium telecommunications constellation, each orbiting Earth every 100 minutes.

During this talk, you will discover how a physical process called magnetic reconnection links the Sun to the Earth on the day side of our planet, and how it severs that link on the night side. John will present an overview of the current systems which flow in the magnetosphere and the ionosphere, before giving a guided tour of his research showing how Birkeland currents react to magnetic reconnection on both sides of Earth, and how this reaction changes with the season due to the effects of sunlight on the atmosphere. Finally, John will discuss a new discovery, as it becomes apparent that the currents in the Northern and Southern Hemispheres show a hitherto unseen asymmetry.


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