“St. Patrick’s Day Storm: an analysis of the geomagnetic field fluctuations”

Liegi, Belgio

We analyze minute values of ground-based geomagnetic fluctuations at about 50 observatories located at throughout the Northern Hemisphere during the St. Patrick's storm in March 2015. The application of the "Empirical Mode Decomposition" method, which is well suitable for the analysis of signals resulting from non-linear and non-stationary processes, it allows the separation of fluctuations on different time scales (short < 200 min, and long > 200 min). The different contribution to the source signal of short and long fluctuations, associated with different magnetospheric processes, is analyzed as a function of latitude during the geomagnetic storm. The weight of the signal related to the fluctuations on a short time scale shows a dependence on the latitude and geomagnetic activity level.