Efficacy of Electric Field Models in Reproducing Observed Ring Current Ion Spectra During Two Geomagnetic Storms

We use the UNH‐IMEF, Weimer 1996, https://doi.org/10.1029/96GL02255 and Volland‐Stern electric field models along with a dipole magnetic field to calculate drift paths for particles that reach the Van Allen Probes' orbit for two inbound passes during two large geomagnetic storms. We compare the...

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Bibliographic Details
Published in:Journal of geophysical research. Space physics 2019-11, Vol.124 (11), p.8974-8991
Main Authors: Menz, A.M., Kistler, L.M., Mouikis, C.G., Matsui, H., Spence, H.E., Thaller, S.A., Wygant, J.R.
Format: Article
Language:English
Subjects:
Charge exchange
Dipoles
Drift estimation
Electric field strength
Electric fields
Geomagnetic storms
Geomagnetism
Ions
Magnetic fields
Magnetic storms
Model accuracy
Model testing
Ring currents
Solar wind
Solar wind models
Storms
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Summary:We use the UNH‐IMEF, Weimer 1996, https://doi.org/10.1029/96GL02255 and Volland‐Stern electric field models along with a dipole magnetic field to calculate drift paths for particles that reach the Van Allen Probes' orbit for two inbound passes during two large geomagnetic storms. We compare the particle access in the models with the observed particle access using both realistic and enhanced solar wind model parameters. To test the accuracy of the drift paths, we estimate the H+ charge exchange loss along these drift paths. While increasing the strength of the model electric field drives particles further inward, improving agreement, energy‐dependent cutoffs in the spectra do not agree, indicating that potential patterns for highly disturbed times are inaccurate. While none of the models were able to reproduce the observed features of the more dawnward pass during the 17 March 2013 storm, the UNH‐IMEF model with enhanced inputs was able to adequately reproduce the access, charge exchange loss, and H+ particle pressure during the 17 March 2015 storm. Key Points Storm time drift trajectories using the UNH‐IMEF model are compared with results using Weimer and Volland‐Stern models The electric field models are too weak in the inner magnetosphere, and particles do not convect in as far as observed without enhanced inputs Additional change to the potential patterns for highly disturbed times is necessary to reproduce observed energy cutoffs
ISSN:2169-9380
2169-9402
DOI:10.1029/2019JA026683