Bibliography

Generation of Subauroral Longitudinally Extended Emissions Following Intensifications of the Poleward Boundary of the Substorm Bulge and Streamer Production

Observations showing the development of Subauroral Longitudinally Extended Emigerssions on a global scale are presented. It is demonstrated that they occur as a separation of an east-west arc-like band of luminosity that detaches away from the equatorward edge of the auroral distribution following episodes of auroral streamer production. They persist for time intervals on the order of ∼30 min and devolve into patchy disjointed segments before they fade. Emissions are seen in both 557.7 nm OI and 391.4 nm 1NG lines, and 630.0 nm emissions are often observed equatorward. The 391.4 nm emissions are typically weaker and fade away more quickly than the 557.7 nm emissions, suggesting that an auroral precipitation source is initially present but is rapidly depleted as the forms age. All cases are associated with enhanced Subauroral Polarization Stream (SAPS) flows, and one event shows clear association with large-scale Giant Undulations (GUs) and the formation of spur-like forms that fold equatorward under the main oval. A model is proposed for the production of subauroral longitudinally extended forms in which nonlinear growth of SAPS-induced surface waves on the plasmapause results in a disruption of the boundary. It is suggested that hot plasma of plasma sheet origin becomes entrained in the plasmasphere to produce transient precipitation-associated auroral emissions that may decay into STEVE emissions and that cold dense plasma from the plasmasphere becomes entrained onto open drift paths to feed long-lived drainage plumes. This process may occur quasi periodically during intense substorms and storm-time conditions.

Henderson, Michael;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2021     DOI: 10.1029/2020JA028556

Giant Undulations; STEVE; streamers; Subauroral Bands; Subauroral Polarization Streams; substorms

Low-Latitude Zonal Ion Drifts and Their Relationship With Subauroral Polarization Streams and Auroral Return Flows During Intense Magnetic Storms

We analyze horizontal plasma drifts measured by the Defense Meteorological Satellite Program satellites during two intense magnetic storms. It is found, for the first time, that westward plasma flows associated with subauroral polarization streams (SAPS) in the dusk-evening sector penetrate continuously to equatorial latitudes. The westward ion drifts between subauroral and equatorial latitudes occur nearly simultaneously. The latitudinal profile of the westward ion drifts at low latitudes (approximately within ±30° magnetic latitude [MLat]) is relatively flat, and the westward ion drifts at the magnetic equator reach 200–300 m s−1. In the dawn-morning sector, eastward ion drifts at subauroral latitudes are also SAPS. The storm-time dawnside auroral boundary moves to ∼±55° MLat, and the dawnside SAPS penetrate to ∼±20° MLat at 0930 local time. A dawnside SAPS flow channel appears to exist, although it is not as well defined as the duskside SAPS flow channel. Thermospheric wind data measured by the Challenging Minisatellite Payload satellite are analyzed, and zonal disturbance winds are derived. Disturbance winds can reach equatorial latitudes rapidly near midnight but are limited to ±40° geographic latitude or higher near noon. The effects of disturbance winds on the zonal ion drifts at middle and low latitudes are discussed. It is suggested that both the westward ion drifts at middle and low latitudes in the dusk-evening sector and the eastward ion drifts at middle and lower latitudes in the dawn-morning sector are caused primarily by penetration of the SAPS and auroral electric fields.

Huang, Chao-Song; Zhang, Yongliang; Wang, Wenbin; Lin, Dong; Wu, Qian;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2021     DOI: 10.1029/2021JA030001

Electric field; Ionosphere; ionospheric plasma drift; penetration electric field; Subauroral Polarization Streams; thermospheric wind