Plasma convection across the polar cap, plasma mantle and cusp: Cluster EDI observations
In this paper we report measurements of the convection obtained with the Electron Drift Instrument (EDI) on Cluster. We use 20 passes that cross the between its dayside and nightside boundaries (or vice versa) at geocentric distances ranging from about 5 to about 13<i>R<sub>E</sub&...
| Main Authors: | , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2004-07-01
|
| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/22/2451/2004/angeo-22-2451-2004.pdf |
| _version_ | 1828727581391716352 |
|---|---|
| author | H. Vaith G. Paschmann J. M. Quinn M. Förster E. Georgescu S. E. Haaland B. Klecker C. A. Kletzing P. A. Puhl-Quinn P. A. Puhl-Quinn H. Rème R. B. Torbert |
| author_facet | H. Vaith G. Paschmann J. M. Quinn M. Förster E. Georgescu S. E. Haaland B. Klecker C. A. Kletzing P. A. Puhl-Quinn P. A. Puhl-Quinn H. Rème R. B. Torbert |
| author_sort | H. Vaith |
| collection | DOAJ |
| description | In this paper we report measurements of the convection obtained with the
Electron Drift Instrument (EDI) on Cluster. We use 20 passes that cross the
between its dayside and nightside boundaries (or vice versa) at
geocentric distances ranging from about 5 to about 13<i>R<sub>E</sub></i>, and at
interspacecraft separations (transverse to the ambient magnetic field)
between a few km and almost 10000km. We first illustrate the nature of
the data by presenting four passes in detail. They demonstrate that the sense
of convection (anti-sunward vs. sunward) essentially agrees with the
expectations based on magnetic reconnection occurring on the dayside or
poleward of the cusp. The most striking feature in the EDI data is the
occurrence of large-amplitude fluctuations that are superimposed on the
average velocities. One type of fluctuation appears to grow when approaching
the dayside boundary. The examples also show that there is a variable
degree of inter-spacecraft correlation, ranging from excellent to poor. We
then present statistical results on all 20 passes. Plotting 10-min averages
of the convection velocities vs. IMF <i>B<sub>z</sub></i> one recovers the expected
dependence, albeit with large scatter. Looking at the variances computed over
the same 10-min intervals, one confirms that there is indeed one type of
contribution that grows towards the dayside boundary, but that variances can
be high anywhere. Finally, computing the inter-spacecraft correlations as a
function of their separation distance transverse to the magnetic field shows
that the average correlation drops with increasing distance, but that even at
distances as large as 5000km the correlation can be very good. To put those
scales into context, the separation distances have also been scaled to
ionospheric altitudes where they range between a few hundred meters and
600km. |
| first_indexed | 2024-04-12T13:59:58Z |
| format | Article |
| id | doaj.art-9bf704d40f2e41d38f43b7420318bae4 |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-04-12T13:59:58Z |
| publishDate | 2004-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-9bf704d40f2e41d38f43b7420318bae42022-12-22T03:30:14ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762004-07-01222451246110.5194/angeo-22-2451-2004Plasma convection across the polar cap, plasma mantle and cusp: Cluster EDI observationsH. Vaith0G. Paschmann1J. M. Quinn2M. Förster3E. Georgescu4S. E. Haaland5B. Klecker6C. A. Kletzing7P. A. Puhl-Quinn8P. A. Puhl-Quinn9H. Rème10R. B. Torbert11Max-Planck-Institut für extraterrestrische Physik, 85748 Garching, GermanyMax-Planck-Institut für extraterrestrische Physik, 85748 Garching, GermanyUniversity of New Hampshire, Durham, NH 03824, USAMax-Planck-Institut für extraterrestrische Physik, 85748 Garching, GermanyMax-Planck-Institut für extraterrestrische Physik, 85748 Garching, GermanyMax-Planck-Institut für extraterrestrische Physik, 85748 Garching, GermanyMax-Planck-Institut für extraterrestrische Physik, 85748 Garching, GermanyUniversity of Iowa, Iowa City, IA 52242, USAMax-Planck-Institut für extraterrestrische Physik, 85748 Garching, GermanyUniversity of New Hampshire, Durham, NH 03824, USACESR-CNRS, 31028 Toulouse, FranceUniversity of New Hampshire, Durham, NH 03824, USAIn this paper we report measurements of the convection obtained with the Electron Drift Instrument (EDI) on Cluster. We use 20 passes that cross the between its dayside and nightside boundaries (or vice versa) at geocentric distances ranging from about 5 to about 13<i>R<sub>E</sub></i>, and at interspacecraft separations (transverse to the ambient magnetic field) between a few km and almost 10000km. We first illustrate the nature of the data by presenting four passes in detail. They demonstrate that the sense of convection (anti-sunward vs. sunward) essentially agrees with the expectations based on magnetic reconnection occurring on the dayside or poleward of the cusp. The most striking feature in the EDI data is the occurrence of large-amplitude fluctuations that are superimposed on the average velocities. One type of fluctuation appears to grow when approaching the dayside boundary. The examples also show that there is a variable degree of inter-spacecraft correlation, ranging from excellent to poor. We then present statistical results on all 20 passes. Plotting 10-min averages of the convection velocities vs. IMF <i>B<sub>z</sub></i> one recovers the expected dependence, albeit with large scatter. Looking at the variances computed over the same 10-min intervals, one confirms that there is indeed one type of contribution that grows towards the dayside boundary, but that variances can be high anywhere. Finally, computing the inter-spacecraft correlations as a function of their separation distance transverse to the magnetic field shows that the average correlation drops with increasing distance, but that even at distances as large as 5000km the correlation can be very good. To put those scales into context, the separation distances have also been scaled to ionospheric altitudes where they range between a few hundred meters and 600km.https://www.ann-geophys.net/22/2451/2004/angeo-22-2451-2004.pdf |
| spellingShingle | H. Vaith G. Paschmann J. M. Quinn M. Förster E. Georgescu S. E. Haaland B. Klecker C. A. Kletzing P. A. Puhl-Quinn P. A. Puhl-Quinn H. Rème R. B. Torbert Plasma convection across the polar cap, plasma mantle and cusp: Cluster EDI observations Annales Geophysicae |
| title | Plasma convection across the polar cap, plasma mantle and cusp: Cluster EDI observations |
| title_full | Plasma convection across the polar cap, plasma mantle and cusp: Cluster EDI observations |
| title_fullStr | Plasma convection across the polar cap, plasma mantle and cusp: Cluster EDI observations |
| title_full_unstemmed | Plasma convection across the polar cap, plasma mantle and cusp: Cluster EDI observations |
| title_short | Plasma convection across the polar cap, plasma mantle and cusp: Cluster EDI observations |
| title_sort | plasma convection across the polar cap plasma mantle and cusp cluster edi observations |
| url | https://www.ann-geophys.net/22/2451/2004/angeo-22-2451-2004.pdf |
| work_keys_str_mv | AT hvaith plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT gpaschmann plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT jmquinn plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT mforster plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT egeorgescu plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT sehaaland plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT bklecker plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT cakletzing plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT papuhlquinn plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT papuhlquinn plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT hreme plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations AT rbtorbert plasmaconvectionacrossthepolarcapplasmamantleandcuspclusterediobservations |