Oxygen ion beams at the boundary of velocity dispersed ion structures in the high-latitude magnetosphere under northward interplanetary magnetic field with a large by-component: Interball-tail observations

Popielawska, B.; Sandahl, I.; Joko, S.; Stenuit, H.; Романов, С. А.; Захаров, А. В.

doi:10.1016/s0273-1177(02)00949-3

Cited by 1 publication

(2 citation statements)

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“…Mapping results with the T96 model by Popielawska et al (2003) of velocity dispersed ion structures (appearing at the time period of the auroral spiral) show a rather unrealistic tail source region. As they mention, standard magnetosphere models do probably not cover such extreme solar wind conditions very well.…”

Section: Formation Of Spiralmentioning

confidence: 91%

“…This CME event has been studied by several other authors, using it as a test case to examine a geomagnetic sudden commencement model (Lam and Rodger, 2001), focusing on airglow structures in the midlatitude ionosphere (Garcia et al, 2000), examining high-energetic ion beams near the velocity dispersion boundary of the high-latitude ionosphere (Popielawska et al, 2003), and being included in a smaller statistical study of stormtime substorms (Wu et al, 2004). Garcia et al (2000) and Popielawska et al (2003) observations show that the entire magnetosphere was in an extremely unusual state. Instead of putting the giant spiral as an outlier to the side we have asked ourselves which conditions of the solar wind and their history might have caused this unusual auroral form.…”

Section: Introductionmentioning

confidence: 99%

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An unusual giant spiral arc in the polar cap region during the northward phase of a Coronal Mass Ejection

Rosenqvist

Kullén²,

Buchert³

2007

Ann. Geophys.

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Abstract. The shock arrival of an Interplanetary Coronal Mass Ejection (ICME) at ∼09:50 UT on 22 November 1997 resulted in the development of an intense (D st <−100 nT) geomagnetic storm at Earth. In the early, quiet phase of the storm, in the sheath region of the ICME, an unusual large spiral structure (diameter of ∼1000 km) was observed at very high latitudes by the Polar UVI instrument. The evolution of this structure started as a polewardly displaced auroral bulge which further developed into the spiral structure spreading across a large part of the polar cap. This study attempts to examine the cause of the chain of events that resulted in the giant auroral spiral. During this period the interplanetary magnetic field (IMF) was dominantly northward (B z >25 nT) with a strong duskward component (B y >15 nT) resulting in a highly twisted tail plasma sheet. Geotail was located at the equatorial dawnside magnetotail flank and observed accelerated plasma flows exceeding the solar wind bulk velocity by almost 60%. These flows are observed on the magnetosheath side of the magnetopause and the acceleration mechanism is proposed to be typical for strongly northward IMF. Identified candidates to the cause of the spiral structure include a B y induced twisted magnetotail configuration, the development of magnetopause surface waves due to the enhanced pressure related to the accelerated magnetosheath flows aswell as the formation of additional magnetopause deformations due to external solar wind pressure changes. The uniqeness of the event indicate that most probably a combination of the above effects resulted in a very extreme tail topology. However, the data coverage is insufficient to fully investigate the physical mechanism behind the observations.

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Section: Formation Of Spiralmentioning

confidence: 91%