Short timescale magnetic field fluctuations and their impact on space weather forecasting

The features of the horizontal intensity of the geomagnetic field fluctuations during a geomagnetically disturbed period are analyzed. The Empirical Mode Decomposition (EMD) method is applied to separate short timescale (T<200 min) and long timescale (T>200 min) magnetic field fluctuations, which have been suggested to be related to different physical processes. The magnetic fluctuations at long timescales (T>200 min) seem to show a large degree of correlation between solar wind parameters and magnetospheric dynamics proxies, while the magnetic field fluctuations at short timescales (T<200 min) seem to be essentially related to internal magnetospheric processes and not directly driven by interplanetary changes.

Daily maps of the short timescale magnetic field fluctuations during a selected period are analyzed in order to investigate their contribution to the total magnetic signal. The aim is to evaluate the role that the internal magnetospheric processes have on the magnetic signal recorded on the ground and to investigate their dependence on the geomagnetic activity level. A comparison between the two hemispheres is also shown. The obtained results can be useful in the Space weather framework. They show the magnetic field fluctuation forecasting requires the development of models that take into account not only the solar wind parameters but also the internal dynamics of the magnetosphere that although triggered by changes of the interplanetary conditions is not directly driven by solar wind/interplanetary magnetic field.