During June and July last year, Milla and I attended the Los Alamos summer school that focused on space weather. This was run by the Los Alamos National Laboratory, which is a national laboratory in New Mexico, USA. Unfortunately, the pandemic meant that we attended this summer school remotely rather than travelling to the USA, but this was still a really interesting experience and we learnt a lot!
We both did a research project on electrons in the Earth’s radiation belts, attended lectures about space physics and the principles of satellite measurements, and (virtually) met people working at the Los Alamos National Laboratory. While the laboratory is more known for its nuclear research, it hosts extensive investigations in space physics, including the study of the radiation belt environment.
In my project, I studied the electron dynamics in the outer radiation belt during the October 2012 geomagnetic storm, examining the contributions of different processes to losses through the magnetopause. My primary mentor, Geoff Reeves, also studied this storm; one of the first key results of the Van Allen probes era was his discovery that local acceleration was primarily responsible for electron enhancement during this storm. In my study, I used the DREAM3D simulation to model the electron dynamics during this storm, studying how different radial diffusion models and the inclusion of drift orbit bifurcation affected the electron losses at high L*. In this project, I found that it is essential to model radial diffusion with a non-dipolar magnetic field model to properly evaluate the contribution of radial diffusion to loss through the magnetopause. I also found that the treatment of electrons with bifurcated drift orbits significantly affects the loss calculation.
Milla’s project was also about the electron dynamics in the outer radiation belt. She studied how the electron content changes in response to the impact of the sheath regions of interplanetary coronal mass ejections. Particularly, she performed this work with observations from the Global Positioning System (GPS) Constellation – a dataset that was recently made public by the Los Alamos National Laboratory. She learnt how to use these data and the related models with the guidance of her primary mentor Michael Henderson. The advantage of GPS satellites to other spacecraft measuring the radiation belts is their number: measurements from the currently over 20 satellites provide much better resolution in time and location than other missions. This allowed Milla to study how electrons change on short timescales, down to 30 minutes, which can reveal more information about the loss and acceleration processes occurring in the outer radiation belt.
Both Harriet and Milla are currently finalising a research paper related to their summer school projects that will be submitted into a peer-reviewed journal of the field.