Joe's thesis work is on networks and space weather, in collaboration with his PhD supervisor Sandra Chapman, and SuperMag PI Jesper Gjerloev, see for example:

J. Dods, S. C. Chapman, and J. W. Gjerloev, Network Analysis of Geomagnetic Substorms Using the SuperMAG Database of Ground Based Magnetometer Stations, J. Geophys. Res., 120, doi:10.1002/2015JA021456 (2015)