Journal Article

Modeling Equatorial Plasma Bubbles With SAMI3/WACCM‐X: September 2017 Storm

Lu, G., Huba, J. D.

2024

Overview

We report results from a global simulation of the September 2017 geomagnetic storm. The global model comprises the ionospheric code SAMI3 and the atmosphere/thermosphere code WACCM‐X. We show that a train of large‐scale EPBs form in the Pacific sector during the storm recovery phase on 8 September 2017. The EPBs are associated with storm‐induced modification of the zonal and meridional winds. These changes lead to an eastward electric field which in turn causes an upward E × B drift in the post‐midnight sector. A large decrease in the Pedersen conductance caused by meridional equatorward winds leads to an increase in the growth rate of the generalized Rayleigh‐Taylor instability that causes EPBs to develop. Interestingly, several EPBs reach altitudes above 3,000 km. Plain Language Summary The uppermost layer of the atmosphere, the thermosphere, is heated at high latitudes during geomagnetic storms by energy inputs from the magnetosphere. This heating significantly modulates the thermosphere winds on a global scale that results in the modification of the electrodynamics of the ionosphere at low‐ to mid‐latitudes. Using the coupled SAMI3/WACCM‐X model, we show that equatorial plasma bubbles (EPBs) (large‐scale depletions of the electron density in the ionosphere) can develop because of these stormtime changes to the winds and electric field. This is significant because EPBs can adversely impact space‐based communication and navigation systems by degrading the reception of electromagnetic signals that pass through them. Key Points Stormtime modulation of the zonal and meridional winds increase the eastward electric field at night in the Pacific sector Equatorial plasma bubbles subsequently develop in the Pacific sector during the September 2017 storm on September 8 Several equatorial plasma bubbles rise to over 3,000 km with upward velocities exceeding 300 m/s

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Atmosphere / Bubbles / disturbance dynamo / Electric field / Electric fields / Electrodynamics / Electron density / equatorial plasma bubbles / Geomagnetic storms / Geomagnetism / Growth rate / Ionosphere / Ionospheric models / Latitude / Magnetic storms / Magnetospheres / Meridional wind / Navigation systems / Plasma bubbles / Storms / stormtime winds / Taylor instability / Thermosphere / Winds