Polar ionospheric responses to solar wind IMF changes
Auroral and airglow emissions over Eureka (89<sup>°</sup> CGM) during the 1997-98 winter show striking variations in relation to solar wind IMF changes. The period January 19 to 22, 1998, was chosen for detailed study, as the IMF was particularly strong and variable. During most of th...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2000-06-01
|
| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/18/629/2000/angeo-18-629-2000.pdf |
| Summary: | Auroral and airglow emissions over Eureka (89<sup>°</sup>
CGM) during the 1997-98 winter show striking variations in relation to solar
wind IMF changes. The period January 19 to 22, 1998, was chosen for detailed
study, as the IMF was particularly strong and variable. During most of the
period, <i>B<sub>z</sub></i> was northward and polar arcs were observed. Several
overpasses by DMSP satellites during the four day period provided a clear
picture of the particle precipitation producing the polar arcs. The spectral
character of these events indicated excitation by electrons of average energy
300 to 500 eV. Only occasionally were electrons of average energy up to ~1 keV
observed and these appeared transitory from the ground optical data. It is noted
that polar arcs appear after sudden changes in IMF <i>B<sub>y</sub></i>,
suggesting IMF control over arc initiation. When <i>B<sub>y</sub></i> is
positive there is arc motion from dawn to dusk, while <i>B<sub>y</sub></i> is
negative the motion is consistently dusk to dawn. F-region (anti-sunward)
convections were monitored through the period from 630.0 nm emissions. The
convection speed was low (100-150 m/s) when <i>B<sub>z</sub></i> was northward
but increased to 500 m/s after <i>B<sub>z</sub></i> turned southward on January
20.<br><br><b>Key words: </b>Atmospheric composition and structure
(airglow and aurora) - Ionosphere (particle precipitation) - Magnetospheric
Physics (polar cap phenomena) |
|---|---|
| ISSN: | 0992-7689 1432-0576 |