Traveling Ionospheric Disturbances in the Vicinity of Storm‐Enhanced Density at Midlatitudes
Abstract
This study provides first storm time observations of the westward‐propagating medium‐scale traveling ionospheric disturbances (MSTIDs), particularly, associated with characteristic subauroral storm time features, storm‐enhanced density (SED), subauroral polarization stream (SAPS), and enhanced thermospheric westward winds over the continental US. In the four recent (2017–2019) geomagnetic storm cases examined in this study (i.e., 2018‐08‐25/26, 2017‐09‐07/08, 2017‐05‐27/28, and 2016‐02‐02/03 with minimum SYM‐H index −206, −146, −142, and −58 nT, respectively), MSTIDs were observed from dusk‐to‐midnight local times predominately during the intervals of interplanetary magnetic field (IMF) Bz stably southward. Multiple wavefronts of the TIDs were elongated NW‐SE, 2°–3° longitude apart, and southwestward propagated at a range of zonal phase speeds between 100 and 300 m/s. These TIDs initiated in the northeastern US and intensified or developed in the central US with either the coincident SED structure (especially the SED basis region) or concurrent small electron density patches adjacent to the SED. Observations also indicate coincident intense storm time electric fields associated with the magnetosphere–ionosphere–thermosphere coupling electrodynamics at subauroral latitudes (such as SAPS) as well as enhanced thermospheric westward winds. We speculate that these electric fields trigger plasma instability (with large growth rates) and MSTIDs. These electrified MSTIDs propagated westward along with the background westward ion flow which resulted from the disturbance westward wind dynamo and/or SAPS.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Aug 01, 2022
- Source ID
- 10.1029/2022ja030429
Entities
People
- Anthea J. Coster
- E. G. Thomas
- Ercha Aa
- Hyosub Kil
- Juha Vierinen
- Philip J. Erickson
- Robert Kerr
- Shun-Rong Zhang
- William C. Rideout
- Yue Deng
- Yukitoshi Nishimura
Organizations
- Air Force Office of Scientific Research
- Boston University
- Dartmouth College
- Johns Hopkins University
- Massachusetts Institute of Technology
- National Aeronautics and Space Administration
- National Science Foundation
- Office of Naval Research
- University of Texas at Arlington
- University of Tromsø – The Arctic University of Norway