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Night-time Ionospheric Localized Enhancements (NILE) Observed in North America Following Geomagnetic Disturbances
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  • Alex T Chartier,
  • Seebany Datta-Barua,
  • Sarah E McDonald,
  • Jennifer L Tate,
  • Gary Steven Bust,
  • Giuseppe Romeo,
  • Robert K Schaefer,
  • Larisa P. Goncharenko
Alex T Chartier
Johns Hopkins University Applied Physics Laboratory

Corresponding Author:alex.chartier@jhuapl.edu

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Seebany Datta-Barua
Illinois Institute of Technology
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Sarah E McDonald
Naval Research Laboratory
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Jennifer L Tate
Computational Physics, Inc.
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Gary Steven Bust
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Giuseppe Romeo
Johns Hopkins University
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Robert K Schaefer
Johns Hopkins University/APL
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Larisa P. Goncharenko
Massachusetts Institute of Technology, Haystack Observatory
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The Ionospheric Data Assimilation Four-Dimensional (IDA4D) technique has been coupled to Sami3 is Another Model of the Ionosphere (SAMI3). In this application, ground- and space-based GPS Total Electron Content (TEC) data have been assimilated into SAMI3, while in situ electron densities, autoscaled ionosonde NmF2 and reference GPS stations have been used for validation. IDA4D/SAMI3 shows that Night-time Ionospheric Localized Enhancements (NILE) are formed following geomagnetic storms in November 2003 and August 2018. The NILE phenomenon appears as a moderate, longitudinally extended enhancement of NmF2 at 30-40o N MLAT, occurring in the late evening (20-24 LT) following much larger enhancements of the equatorial anomaly crests in the main phase of the storms. The NILE appears to be caused by upward and northward plasma transport around the dusk terminator, which is consistent with eastward polarization electric fields. Independent validation confirms the presence of the NILE, and indicates that IDA4D is effective in correcting random errors and systematic biases in SAMI3. In all cases, biases and root-mean-square errors are reduced by the data assimilation, typically by a factor of 2 or more. During the most severe part of the November 2003 storm, the uncorrected ionospheric error on a GPS 3D position at 1LSU (Louisiana) is estimated to exceed 34 m. The IDA4D/SAMI3 specification is effective in correcting this down to 10-m.
Sep 2021Published in Journal of Geophysical Research: Space Physics volume 126 issue 9. 10.1029/2021JA029324