https://phys.org/news/2019-01-space-weather-arctic-regions-technique.html

"The fractional derivative rate (FDR) technique that we have developed calculates for each day percentage which indicates how often the activeness of the magnetic field has reached a level of 0.2 nT/s (nanoteslas per second) on that day. This value corresponds to the typical initial stage of a substorm, which is one of the most common space weather phenomena. This technique makes it easier to analyse high resolution observation data for long periods of time," explains Doctoral Candidate Pyry Peitso.

Magnetic field can be used to forecast space weather