 |
| Titel |
SuperDARN studies of the ionospheric convection response to a northward turning of the interplanetary magnetic field |
| VerfasserIn |
J. R. Taylor, S. W. H. Cowley, T. K. Yeoman, Mark Lester, T. B. Jones, R. A. Greenwald, G. Sofko, J.-P. Villain, R. P. Lepping, M. R. Hairston |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 16, no. 5 ; Nr. 16, no. 5, S.549-565 |
| Datensatznummer |
250013275
|
| Publikation (Nr.) |
 copernicus.org/angeo-16-549-1998.pdf |
|
|
|
|
|
| Zusammenfassung |
The response of the dayside ionospheric flow
to a sharp change in the direction of the interplanetary magnetic field (IMF)
measured by the WIND spacecraft from negative Bz and positive By,
to positive Bz and small By, has been
studied using SuperDARN radar, DMSP satellite, and ground magnetometer data. In
response to the IMF change, the flow underwent a transition from a distorted
twin-cell flow involving antisunward flow over the polar cap, to a multi-cell
flow involving a region of sunward flow at high latitudes near noon. The radar
data have been studied at the highest time resolution available (~2 min) to
determine how this transition took place. It is found that the dayside flow
responded promptly to the change in the IMF, with changes in radar and magnetic
data starting within a few minutes of the estimated time at which the effects
could first have reached the dayside ionosphere. The data also indicate that
sunward flows appeared promptly at the start of the flow change (within ~2 min),
localised initially in a small region near noon at the equatorward edge of the
radar backscatter band. Subsequently the region occupied by these flows expanded
rapidly east-west and poleward, over intervals of ~7 and ~14 min respectively,
to cover a region at least 2 h wide in local time and 5° in latitude, before
rapid evolution ceased in the noon sector. In the lower latitude dusk sector the
evolution extended for a further ~6 min before quasi-steady conditions again
prevailed within the field-of-view. Overall, these observations are shown to be
in close conformity with expectations based on prior theoretical discussion,
except for the very prompt appearance of sunward flows after the onset of the
flow change.
Key words. Ionosphere (Auroral ionosphere) ·
Magnetospheric physics (Magnetopause · cusp · and boundary layers;
Magnetosphere · ionosphere interaction) |
| |
|
| Teil von |
|
|
|
|
|
|
|
|