Trial lecture and PhD defense for Charlotte Maartje van Hazendonk

Charlotte will defend the PhD degree at The University in Bergen, Faculty of Science and Technology, Department of Physics and Technology at UNIS 10 February 2026:

«The effect of ultra-low frequency waves on magnetosphere-ionosphere coupling at high-latitude»

In her doctoral research at the University of Bergen and the University Centre in Svalbard (UNIS), Charlotte Maartje van Hazendonk has investigated how ultra-low-frequency waves are generated, how they propagate, and how they transfer energy, with a particular focus on their role in coupling the magnetosphere and the ionosphere.

The study employs a unique combination of ground-based radar measurements, optical observations of the aurora borealis, satellite data, and advanced analysis and inversion models. Its aim is to quantify how much the ULF waves deposit in the ionosphere, as well as how they drive electric currents and particle motions along the Earth’s magnetic field lines.

Van Hazendonk’s research shows that ULF-waves can transfer more energy to the ionosphere than previously assumed, and that they play an important role in the coupling between the magnetosphere and the ionosphere. Statistical analyses of nearly 200 auroral events provide new insight into the types of ULF waves capable of driving auroral arcs – including small-scale ULF waves – and show that these arcs can also propagate towards the equator.

Furthermore, the thesis documents, for the first time, a direct connection between such auroral arcs and the upwelling of ions in the ionosphere.