Azimuthal flow bursts in the inner plasma sheet and possible connection with SAPS and plasma sheet earthward flow bursts

Lyons, L. R.; Nishimura, Y.; Gallardo‐Lacourt, B.; Nicolls, M. J.; Chen, S.; Hampton, D. L.; Bristow, W. A.; Ruohoniemi, J. M.; Нишитани, Н.; Donovan, E.; Angelopoulos, V.

doi:10.1002/2015ja021023

Cited by 37 publications

(38 citation statements)

References 45 publications

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“…Makarevich et al () used IMAGE FUV and radar data to present a case study in which they suggested that a strong enhancement of SAPS flows occurred in association with an auroral streamer. Similar results were found by Lyons et al (). If auroral streamers are commonly associated with SAPS intensification, it would imply that transient fast earthward plasma sheet flows are associated with westward SAPS flow enhancements.…”

Section: Introductionsupporting

confidence: 92%

Influence of Auroral Streamers on Rapid Evolution of Ionospheric SAPS Flows

et al. 2017

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Subauroral polarization streams (SAPS) often show large, rapid enhancements above their slowly varying component. We present simultaneous observations from ground‐based all‐sky imagers and flows from the Super Dual Auroral Radar Network radars to investigate the relationship between auroral phenomena and flow enhancement. We first identified auroral streamers approaching the equatorward boundary of the auroral oval to examine how often the subauroral flow increased. We also performed the reverse query starting with subauroral flow enhancements and then evaluated the auroral conditions. In the forward study, 98% of the streamers approaching the equatorward boundary were associated with SAPS flow enhancements reaching ~700 m/s and typically hundreds of m/s above background speeds. The reverse study reveals that flow enhancements associated with streamers (60%) and enhanced larger‐scale convection (37%) contribute to SAPS flow enhancements. The strong correlation of auroral streamers with rapid evolution (approximately minutes) of SAPS flows suggests that transient fast earthward plasma sheet flows can often lead to westward SAPS flow enhancements in the subauroral region and that such enhancements are far more common than only during substorms because of the much more frequent occurrences of streamers under various geomagnetic conditions. We also found a strong correlation between flow duration and streamer duration and a weak correlation between SAPS flow velocity and streamer intensity. This result suggests that intense flow bursts in the plasma sheet (which correlate with intense streamers) are associated with intense SAPS ionospheric flows perhaps by enhancing the ring current pressure and localized pressure gradients when they are able to penetrate close enough to Earth.

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Section: Introductionsupporting

confidence: 92%

Influence of Auroral Streamers on Rapid Evolution of Ionospheric SAPS Flows

et al. 2017

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“…Narrow channels of enhanced westward ion velocity (shown in green) were also observed roughly colocated with the minimum n e for all cases in which the Swarm EFI was operating. We also note that while SAID are reported between 16 and 2 hr MLT with the highest occurrence probability density around 22 MLT (He et al, 2014;Spiro et al, 1979), all Steve events presented so far have been between 22 and 2 MLT. It should be noted that because there are no v i measurements available for four of the events in Figure 1, they do not meet the criteria used in this study to identify SAID.…”

Section: Steve Measurements With Swarmmentioning

confidence: 53%

Steve: The Optical Signature of Intense Subauroral Ion Drifts

Archer

Gallardo‐Lacourt

Perry

et al. 2019

Geophysical Research Letters

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102

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Little is currently known about the optical phenomenon known as Steve. The first scientific publication on the subject suggests that Steve is associated with an intense subauroral ion drift (SAID). However, additional inquiry is warranted as this suggested relationship as it is based on a single case study. Here we present eight occurrences of Steve with coincident or near‐coincident measurements from the European Space Agency's Swarm satellites and show that Steve is consistently associated with SAID. When satellite observations coincident with Steve are compared to that of typical SAID, we find the SAID associated with Steve to have above average peak ion velocities and electron temperatures, as well as extremely low plasma densities.

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“…Here we applied a single-layer model with a fixed altitude of the layer at 350 km to all geographical latitudes, but we can also mention several other approaches which can be applied to retrieve vertical TEC at equatorial latitudes, particularly, using the higher-elevation cutoff mask [e.g., Paul et al, 2011;Sur et al, 2015] or using the modified dip latitude [e.g., Azpilicueta et al, 2006;Brunini and Azpilicueta, 2010]. As a result for each station we obtain TEC values along all visible (GPS or GLONASS) satellites with 30 s sampling period.…”

Section: Data and Methods Usedmentioning

confidence: 99%

GPS and GLONASS observations of large‐scale traveling ionospheric disturbances during the 2015 St. Patrick's Day storm

2016

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Using a comprehensive database of ~5300 ground‐based Global Navigation Satellite Systems (GNSS) stations we have investigated large‐scale traveling ionospheric disturbances (LSTIDs) during 17–18 March 2015 (St. Patrick's Day storm). For the first time, the high‐resolution, two‐dimensional maps of the total electron content perturbation were made using not only GPS but also GLONASS measurements. Several LSTIDs originated from the auroral regions in the Northern and Southern Hemispheres were observed simultaneously over Europe, North America, and South America. This storm is considered as a two‐step main phase storm. During the first main phase LSTIDs propagated over the whole daytime European region and over high latitudes of North America. During the second main phase we report (1) intense LSTIDs propagated equatorward in North America and Europe, (2) convergence of several LSTIDs originated from the opposite hemispheres in the interference zone over geomagnetic equator in South America, and (3) “super” LSTIDs with the wavefront length of more than 10,000 km observed simultaneously in North America and Europe. LSTIDs observed in three sectors had wavelength of ~1200–2500 km and wave periods of ~50–80 min. During the recovery phase on the background of the negative ionospheric storm developed over North America we detect signatures of the stream‐like structures elongated within the latitudinal range of 29°N–42°N across the U.S. These structures persisted through the nighttime to the early morning from 04 UT to 13 UT on 18 March 2015, and they were associated with the subauroral polarization stream‐induced nighttime ionospheric flows.

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Azimuthal flow bursts in the inner plasma sheet and possible connection with SAPS and plasma sheet earthward flow bursts

Cited by 37 publications

References 45 publications

Influence of Auroral Streamers on Rapid Evolution of Ionospheric SAPS Flows

Influence of Auroral Streamers on Rapid Evolution of Ionospheric SAPS Flows

Steve: The Optical Signature of Intense Subauroral Ion Drifts

GPS and GLONASS observations of large‐scale traveling ionospheric disturbances during the 2015 St. Patrick's Day storm

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