 |
| Titel |
Observations of reversed flow channels in the winter cusp ionosphere by EISCAT Svalbard Radar |
| VerfasserIn |
Jøran Moen, Yvonne Rinne, Kjellmar Oksavik, Herbert C. Carlson, Ryoichi Fujii |
| Konferenz |
EGU General Assembly 2010
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037355
|
|
|
|
|
|
| Zusammenfassung |
| A new category of flow channels, named Reversed Flow Events (RFEs), has been discovered
by EISCAT Svalbard Radar. An RFE is a longitudinally elongated, 100-200 km wide channel,
in which the flow direction is opposite to the background convection, persisting for 10-20
min. In this paper we study RFEs that seem regulated by Birkeland current arcs in the winter
cusp ionosphere above Svalbard. The RFE onset occurs with brightening of a discrete arc
near the open closed boundary. The auroral arc is situated exactly at a sharp clockwise flow
reversal, consistent with a converging electric field and an upward field-aligned current. One
category of RFEs propagates into the polar cap in tandem with poleward moving auroral
forms, while another category of RFEs moves with the equatorward cusp boundary. The RFE
phenomenon is addressed to a region void of electron precipitation, and in lack of
direct sunlight the E-region conductivity will be very low. We propose two possible
explanations: i) The RFE channel may be a region where two MI current loops, forced by
independent voltage generators, couple through a poorly conducting ionosphere. ii) The
reversed flow channel may be the ionospheric footprint of an inverted V- type coupling
region. Electron beams of |
|
|
|
|
|
|