Ionospheric currents and TEC variations during the March 17, 2015 Sudden Impulse.

Piersanti M., Cesaroni C., Spogli L., Alfonsi L., Villante U.
  Mercoledì 28/09   10:00 - 13:00   Edificio Psicologia 2 - Aula 2A   IV - Geofisica, Fisica dell'ambiente
We asses the relationship between ionospheric currents derived by ground magnetometers and Total Electron Content (TEC) derived by GNSS receivers over the European longitudinal sector during the Sudden Impulse (SI) of the 2015 St. Patrick Storm. Since changes in the ionospheric currents are expected to be related to the temporal variation of the Total Electron Content (TEC) in the ionosphere, we compare vertical TEC (vTEC) variations with the relative ionospheric currents corresponding to the Preliminary (PI) and Main Impulses (MI) inferred by the use of Piersanti $et al.$ [2016] SI model. We apply the Ensemble Empirical Mode Decomposition (EEMD, [Huang, 1998]) analysis to vTEC data to discriminate between the diurnal/seasonal and SI-related variations for each co-located GNSS receiver-magnetometer couple. We found a linear relationship between the ionospheric current inferred from ground measurements and the temporal fluctuations of vTEC ($WHT_{5+6}$) induced by the SI for both the PI and the MI (with a slope of $\sim 3.0 \cdot 10^{-4} [H^{-1}])$. In addition, in agreement with the results of Chi $et al.$ [2006] about the propagation of SI signals in the ionosphere, by cross-correlation analysis applied to $WHT_{5+6}$ for each couple of GNSS stations, we obtained a velocity of the disturbance of $\sim 1.5$ km/s.