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Occurrence and prop...
Occurrence and properties of substorms associated with pseudobreakups
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- Kullen, Anita (författare)
- KTH,Rymd- och plasmafysik
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- Karlsson, Tomas (författare)
- KTH,Rymd- och plasmafysik
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- Cumnock, Judy A. (författare)
- KTH,Rymd- och plasmafysik
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- Sundberg, Torbjörn (författare)
- KTH,Rymd- och plasmafysik
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(creator_code:org_t)
- 2010
- 2010
- Engelska.
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 115, s. A12310-
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- We investigate how substorms with and without growth-phase pseudobreakups are affected by solar wind and ionospheric conditions. The study is based on 874 events identified with Polar UVI. An AE index analysis shows that substorms with growth-phase pseudobreakups are typically weak and appear as isolated events after hours of low geomagnetic activity. During the hours before onset the average solar wind merging field E-m is weaker, and the length of time with enhanced values shorter than for regular substorms. Integrating E-m over the last southward IMF period before onset shows an upper limit above which these substorms do not occur. To estimate how much E-m reaches the ionosphere, polar cap potential drop and unified PC indices are examined. It is found that substorms with growth-phase pseudobreakups have on average lower PC index values than regular substorms. The temporal evolution of the PC indices is similar for both substorm groups; the summer index correlates better with E-m, the winter index with AE. Also the average polar cap potential drop curves for both types of substorms resemble one other; the dayside and nightside curves are mainly influenced by E-m and AE, respectively. Comparing growth-phase, isolated and recovery pseudobreakups shows that solar wind and ionospheric conditions around the first substorm after a pseudobreakup are similar, independent of whether the last pseudobreakup appeared hours (recovery and isolated pseudobreakups) or minutes before substorm onset (growth-phase pseudobreakups). Isolated and recovery pseudobreakups are less often associated with a northward IMF rotation than growth-phase pseudobreakups or substorms.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- solar-wind
- pseudo-breakup
- auroral oval
- polar-cap
- convection
- disturbances
- ionosphere
- dynamics
- flows
- Astronomy and astrophysics
- Astronomi och astrofysik
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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