| 1. |
|
|
| 2. |
- Blomberg, Lars G., et al.
(författare)
-
Solar windmagnetosphere-ionosphere coupling : an event study based on Freja data
- 2004
-
Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier BV. - 1364-6826 .- 1879-1824. ; 66:5, s. 375-380
-
Tidskriftsartikel (refereegranskat)abstract
- Freja data are used to study the relative contributions from the high-latitude (reconnection/direct entry) and low-latitude (viscous interaction) dynamos to the cross-polar potential drop. Convection streamlines which are connected to the high-latitude dynamo may be identified from dispersed magnetosheath ions not only in the cusp/cleft region itself but also several degrees poleward of it. This fact, together with Freja's orbital geometry allows us to infer the potential drop from the high-latitude dynamo as well as to obtain a lower limit to the potential drop from the low-latitude dynamo for dayside Freja passes. All cases studied here are for active magnetospheric conditions. The Freja data suggest that under these conditions at least one third of the potential is generated in the low-latitude dynamo. These observations are consistent with earlier observations of the potential across the low-latitude boundary layer if we assume that the low-latitude dynamo region extends over several tens of Earth radii in the antisunward direction along the tail flanks, and that the majority of the potential drop derives from the sun-aligned component of the electric field rather than from its cross-boundary component, or equivalently, that the centre of the dynamo region is located quite far down tail. A possible dynamo geometry is illustrated.
|
|
| 3. |
- Yamauchi, M., et al.
(författare)
-
Acceleration signatures in the dayside boundary layer and the cusp
- 2001
-
Ingår i: Physics and Chemistry of the Earth, Part C. - 1464-1917 .- 1873-4685. ; 26:03-jan, s. 195-200
-
Tidskriftsartikel (refereegranskat)abstract
- Freja data show various electron acceleration signatures in the cusp and the dayside boundary layer: (1) time dispersive super-Alfvénic electrons followed by strong wave activity which accompanies transient downward super-thermal electron burst in both the boundary layer and the cusp; (2) quasi-stationary bidirectional electron burst coinciding with localized intense field-aligned current in the boundary layer; (3) downgoing electron burst without visible time dispersion in the cusp; and (4) thermal electrons accelerated by electrostatic potential in both the boundary layer and the cusp. The first and last signatures are different between two regions for typical energies and fluxes, and these differences probably reflect the different auroral emission in the cusp proper (red) and the boundary layer (green). Contributions of these electrons to the large-scale field-aligned currents are also different between two regions. The dispersed electron burst is probably accelerated within 1 Re above the ionosphere. From this result we believe that the cusp red aurora is caused mainly by accelerated electrons, but not by the smoothly entering magnetosheath electrons without acceleration. This also requires revisions of flux transfer event models for the structured cusp red aurora.
|
|
| 4. |
- Yamauchi, M, et al.
(författare)
-
Acceleration signatures in the dayside boundary layer and the cusp
- 2001
-
Ingår i: PHYSICS AND CHEMISTRY OF THE EARTH PART C-SOLAR-TERRESTIAL AND PLANETARY SCIENCE. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1464-1917. ; 26:1-3, s. 195-200 Language: English
-
Tidskriftsartikel (refereegranskat)abstract
- Freja data show various electron acceleration signatures in the cusp and the dayside boundary layer: (1) time dispersive suger-Alfvenic electrons followed by strong wave activity which accompanies transient downward super-thermal electron burst in both th
|
|
