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Cluster investigations of the extent and altitude distribution of the auroral density cavity [Elektronisk resurs]

Alm, Love (författare)
Marklund, Göran T. (preses)
Karlsson, Tomas (preses)
Lundin, Rickard (opponent)
KTH Skolan för elektro- och systemteknik (EES) (utgivare)
Publicerad: Stockholm : KTH Royal Institute of Technology, 2015
Engelska xi, 58
Serie: TRITA-EE, 1653-5146
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  • E-bokAvhandling(Diss. (sammanfattning) Stockholm : Kungliga Tekniska högskolan, 2015)
Sammanfattning Ämnesord
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  • The auroral density cavity constitutes the boundary between the cold, dense ionospheric plasma and the hot, tenuous plasma sheet plasma. The auroral density cavity is characterized by low electron density and particle populations modified by parallel electric fields. Inside the cavity the electron densities can be as much as a factor 100-1000 lower than same altitude outside the cavity.The Cluster mission's wide range of instruments, long lifetime and ability to make multi-spacecraft observations has been very successful. Over its 15 year lifespan, the Cluster satellites have gathered data on auroral density cavities over a large altitude range and throughout an entire solar cycle, providing a vast data material.The extent of the density cavity and acceleration region is large compared to the typical altitude coverage of a satellite crossing the cavity. This makes it difficult to produce a comprehensive altitude/density profile from a single crossing. In order to facilitate comparisons between data from different events, we introduce a new reference frame, pseudo altitude. Pseudo altitude describes the satellites' position relative to the acceleration region, as opposed to relative to the Earth. This pseudo altitude is constructed by dividing the parallel potential drop below the satellite with the total parallel potential drop. A pseudo altitude of 0 corresponds to the bottom of the acceleration region and a pseudo altitude of 1 to the top of the acceleration region. As expected, the pseudo altitude increases with altitude. The electron density exhibits an anti-correlation with the pseudo altitude, the density becomes lower close to the upper edge of the acceleration region. The upper edge of the acceleration region is located between a geocentric altitude of 4.375 and 5.625 R E . Above the upper edge of the acceleration region, the electron density continues to decrease for the entire range of the study, 3.0-6.5 R E . This is much further than the geocentric altitude range of 2-3 R E which is suggested by previous models. We can conclude that the auroral density cavity is not confined by the auroral acceleration region, as suggested by previous models, and may extend all the way to the plasma sheet. 

Ämnesord

Natural Sciences  (hsv)
Physical Sciences  (hsv)
Fusion, Plasma and Space Physics  (hsv)
Naturvetenskap  (hsv)
Fysik  (hsv)
Fusion, plasma och rymdfysik  (hsv)
Physics  (kth)
Fysik  (kth)

Indexterm och SAB-rubrik

Auroral density cavity
auroral accelaration
Cluster
in situ observation
electron density
pseudo altitude
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"Cluster investigations of the extent and altitude distribution of the auroral density cavity" finns i 2 utgåvor på 1 språk

Engelska (2)

Engelska (2)

TitelUpplagaÅrMaterialtypHitta
Cluster investigations of the extent and altitude dis...2015 3 bibl.
Cluster investigations of the extent and altitude dis...2015 Läs hela
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