Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Substorm Features in the High-Latitude Ionosphere and Magnetosphere: Multi-Instrument Observations
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The space around Earth, confined in the terrestrial magnetosphere, is to some extent shielded from the Sun's solar wind plasma and magnetic field. During certain conditions, however, strong interaction can occur between the solar wind and the magnetosphere, resulting in magnetospheric activity of several forms, among which substorms and storms are the most prominent. A general framework for how these processes work have been outlayed through the history of research, however, there still remain questions to be answered. The most striking example regards the onset of substorms, where both the onset cause and location in the magnetosphere/ionosphere are still debated. These are clearly not easily solved problems, since a substorm is a global process, ideally requiring simultaneous measurements in the magnetotail and ionosphere. Investigated in this work are temporal and spatial scales for substorm and convection processes in the Earth's magnetosphere and ionosphere. This is performed by combining observations from a number of both ground-based and spacecraft-borne instruments. The observations indicate that the magnetotail's cross-section is involved to a larger spatial extent than previously considered in the substorm process. Furthermore, convection changes result in topological changes of the magnetosphere on a fast time scale. The results show that the magnetosphere is, on a global magnetospheric scale, highly dynamic during convection changes and ensuing substorms.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2003. , p. 50
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 860
Keyword [en]
Space and plasma physics, Substorm, Convection, magnetosphere-ionosphere coupling
Keyword [sv]
Rymd- och plasmafysik
National Category
Fusion, Plasma and Space Physics
Research subject
Space and Plasma Physics
Identifiers
URN: urn:nbn:se:uu:diva-3478ISBN: 91-554-5670-7 (print)OAI: oai:DiVA.org:uu-3478DiVA, id: diva2:162986
Public defence
2003-06-05, Polhem, Ångström, Uppsala, 14:00 (English)
Opponent
Supervisors
Available from: 2003-05-15 Created: 2003-05-15 Last updated: 2009-11-18Bibliographically approved
List of papers
1. The dawn and dusk electrojet response to substorm onset
Open this publication in new window or tab >>The dawn and dusk electrojet response to substorm onset
Show others...
2000 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 18, no 9, p. 1097-1107Article in journal (Refereed) Published
Abstract [en]

We have investigated the time delay between substorm onset and related reactions in the dawn and dusk ionospheric electrojets, clearly separated from the nightside located substorm current wedge by several hours in MLT. We looked for substorm onsets occurring over Greenland, where the onset was identified by a LANL satellite and DMI magnetometers located on Greenland. With this setup the MARIA magnetometer network was located at dusk, monitoring the eastward electrojet, and the IMAGE chain at dawn, for the westward jet. In the first few minutes following substorm onset, sudden enhancements of the electrojets were identified by looking for rapid changes in magnetograms. These results show that the speed of information transfer between the region of onset and the dawn and dusk ionosphere is very high. A number of events where the reaction seemed to preceed the onset were explained by either unfavorable instrument locations, preventing proper onset timing, or by the inner magnetosphere's reaction to the Earthward fast flows from the near-Earth neutral line model. Case studies with ionospheric coherent (SuperDARN) and incoherent (EISCAT) radars have been performed to see whether a convection-induced electric field or enhanced conductivity is the main agent for the reactions in the electrojets. The results indicate an imposed electric field enhancement.

Keyword
Polar ionosphere, Electric field, Magnetospheric substorm, Delay time, Auroral electrojet, Radar observation, Magnetometry, Satellite observation, Greenland, North America, America
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-90580 (URN)
Available from: 2003-05-15 Created: 2003-05-15 Last updated: 2017-12-14Bibliographically approved
2. Timing of substorm onset signatures on the ground and at geostationary orbit
Open this publication in new window or tab >>Timing of substorm onset signatures on the ground and at geostationary orbit
2002 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 29, no 12, p. 33(1)-33(4)Article in journal (Refereed) Published
Abstract [en]

In order to study the relative timing of substorm onset signatures on the ground and at geostationary orbit we have used data of simultaneous dispersionless electron and proton injections from the LANL satellite 1991-80, located slightly westward of Scandinavia. Out of 9 years of data we have identified a number of events during which such injections occurred close to local magnetic midnight. By careful inspection of ground-based magnetograms from the Scandinavian magnetometer network, IMAGE, we then identified the location and time of the formation of a substorm current wedge (SCW) during these events. 40 clear cases of geostationary injections, which were clearly associated with the formation of SCWs, were found. A statistical study of these events reveals that there is a clear time delay of the order of several minutes in the occurrence of the substorm injection with respect to the first indication of the SCW measured on the ground.

Keyword
Europe, Scandinavia, Statistical analysis, Ion injection, Magnetosphere, Magnetospheric substorm, Delay time, Magnetogram, Proton, Electron injection, Timing
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-90581 (URN)
Available from: 2003-05-15 Created: 2003-05-15 Last updated: 2017-12-14Bibliographically approved
3. The global ionospheric response to a southward IMF turning
Open this publication in new window or tab >>The global ionospheric response to a southward IMF turning
Show others...
In: Annales Geophysicae, ISSN 0992-7689Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:uu:diva-90582 (URN)
Available from: 2003-05-15 Created: 2003-05-15Bibliographically approved
4. Correlation between ground-based observations of substorm signatures and magnetotail dynamics
Open this publication in new window or tab >>Correlation between ground-based observations of substorm signatures and magnetotail dynamics
Show others...
2005 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 23, p. 997-1011Article in journal (Refereed) Published
Abstract [en]

We present a substorm event study combining Cluster and ground-based instrumentation. For this event ground-based magnetograms show a substorm onset and two separate substorm intensifications over Scandinavia, at the time located in the pre-midnight sector. During the substorm Cluster is located in the southern plasma sheet at a downtail distance of 18.5 Re. For all the substorm signatures seen on ground, corresponding plasma sheet drop-outs and re-entries of all or individual spacecraft of the Cluster constellation are observed. In general, plasma sheet drop-outs are assumed to be due to plasma sheet thinning/thickening and/or to magnetotail flapping. However, in the literature there has been some disagreement on both spatial and temporal characteristics of plasma sheet thinning and thickening during substorms. We therefore investigate the causes for the plasma sheet drop-outs for this event, which at first glance appears to show plasma sheet thinning at substorm onset, contradictory to the present standpoint in the literature.

Keyword
Magnetospheric configuration and dynamics, Magnetotail, Plasma sheet, Storms and substorms
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-90583 (URN)
Available from: 2003-05-15 Created: 2003-05-15 Last updated: 2017-12-14Bibliographically approved
5. Storm-time intense proton aurora and its relation to plasma sheet density
Open this publication in new window or tab >>Storm-time intense proton aurora and its relation to plasma sheet density
In: Annales Geophysicae, ISSN 0092-7689Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:uu:diva-90584 (URN)
Available from: 2003-05-15 Created: 2003-05-15Bibliographically approved

Open Access in DiVA

fulltext(1285 kB)1181 downloads
File information
File name FULLTEXT01.pdfFile size 1285 kBChecksum SHA-1
176b0eb71d1ed402510c2ccbbe5764d404d1d1eb123f883d1a9eff9bd6d4fee7964906c2
Type fulltextMimetype application/pdf
Buy this publication >>

By organisation
Swedish Institute of Space Physics, Uppsala Division
Fusion, Plasma and Space Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 1181 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1621 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf