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Multi-Instrument Characterisation of Magnetospheric Cold Plasma Dynamics in the 22 June 2015 Geomagnetic Storm
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  • Massimo Vellante,
  • Kazue Takahashi,
  • Alfredo Del Corpo,
  • Irina S. Zhelavskaya,
  • Jerry Goldstein,
  • Ian Mann,
  • Ermanno Pietropaolo,
  • Jan Reda,
  • Balazs Heilig
Massimo Vellante
University of L'Aquila

Corresponding Author:[email protected]

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Kazue Takahashi
The Johns Hopkins University Applied Physics Laboratory
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Alfredo Del Corpo
University of L'Aquila
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Irina S. Zhelavskaya
Helmholtz Centre Potsdam, GFZ German Research Centre For Geosciences, Potsdam, Germany
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Jerry Goldstein
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Ian Mann
University of Alberta
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Ermanno Pietropaolo
University of L'Aquila
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Jan Reda
Institute of Geophysics Polish Academy of Sciences
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Balazs Heilig
Mining and Geological Survey of Hungary
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We present a comparison of magnetospheric plasma mass/electron density observations during an 11-day interval which includes the geomagnetic storm of 22 June 2015. For this study we used: equatorial plasma mass density derived from geomagnetic field line resonances (FLRs) detected by Van Allen Probes and at the ground-based magnetometer networks EMMA and CARISMA; in situ electron density inferred by the Neural-network-based Upper hybrid Resonance Determination algorithm applied to plasma wave Van Allen Probes measurements. The combined observations at L ~ 4, MLT ~ 16 of the two longitudinally-separated magnetometer networks show a temporal pattern very similar to that of the in situ observations: a density decrease by an order of magnitude about 1 day after the Dst minimum, a partial recovery a few hours later, and a new strong decrease soon after. The observations are consistent with the position of the measurement points with respect to the plasmasphere boundary as derived by a plasmapause test particle simulation. A comparison between plasma mass densities derived from ground and in situ FLR observations during favourable conjunctions shows a good agreement. We find however, for L < ~3, the spacecraft measurements to be higher than the corresponding ground observations with increasing deviation with decreasing L, which might be related to the rapid outbound spacecraft motion in that region. A statistical analysis of the average ion mass using simultaneous spacecraft measurements of mass and electron density indicates values close to 1 amu in plasmasphere and higher values (~ 2-3 amu) in plasmatrough.