Night-Time Ionospheric Localized Enhancements (NILE) Observed in North America Following Geomagnetic Disturbances

Area of Science:

• Space Physics
• Atmospheric Science
• Geophysics

Background:

• Geomagnetic storms significantly impact the Earth's ionosphere.
• Accurate ionospheric modeling is crucial for satellite-based navigation systems.
• Previous models struggled to capture localized ionospheric phenomena like NILE.

Purpose of the Study:

• To couple the IDA4D technique with the SAMI3 ionospheric model.
• To assimilate GPS total electron content (TEC) data into SAMI3.
• To validate the model's performance in simulating and correcting ionospheric disturbances.

Main Methods:

• Coupling of the IDA4D technique with the SAMI3 ionospheric model.
• Assimilation of ground-based and space-based GPS TEC data.
• Validation using in-situ electron densities, ionosonde NmF2, and reference GPS stations.

Main Results:

• IDA4D/SAMI3 successfully simulated night-time ionospheric localized enhancements (NILE) following geomagnetic storms in November 2003 and August 2018.
• NILE formation linked to upward/northward plasma transport and eastward electric fields near the dusk terminator.
• Data assimilation reduced model biases and root-mean-square errors by a factor of two or more.
• GPS 3D position errors were reduced from over 34m to 10m during a severe storm.

Conclusions:

• The IDA4D/SAMI3 system accurately captures NILE phenomena.
• Data assimilation significantly enhances the accuracy of ionospheric models.
• Improved ionospheric modeling via IDA4D/SAMI3 enhances the precision of GPS positioning.