Small-scale characteristics of extremely high latitude aurora
2009 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 27, no 9, 3335-3347 p.Article in journal (Refereed) Published
We examine 14 cases of an interesting type of extremely high latitude aurora as identified in the precipitating particles measured by the DMSP F13 satellite. In particular we investigate structures within large-scale arcs for which the particle signatures are made up of a group of multiple distinct thin arcs. These cases are chosen without regard to IMF orientation and are part of a group of 87 events where DMSP F13 SSJ/4 measures emissions which occur near the noon-midnight meridian and are spatially separated from both the dawnside and duskside auroral ovals by wide regions with precipitating particles typical of the polar cap. For 73 of these events the high-latitude aurora consists of a continuous region of precipitating particles. We focus on the remaining 14 of these events where the particle signatures show multiple distinct thin arcs. These events occur during northward or weakly southward IMF conditions and follow a change in IMF B-y. Correlations are seen between the field-aligned currents and plasma flows associated with the arcs, implying local closure of the FACs. Strong correlations are seen only in the sunlit hemisphere. The convection associated with the multiple thin arcs is localized and has little influence on the large-scale convection. This also implies that the sunward flow along the arcs is unrelated to the overall ionospheric convection.
Place, publisher, year, edition, pages
2009. Vol. 27, no 9, 3335-3347 p.
Ionosphere, Auroral ionosphere, Electric fields and currents, Particle, precipitation, interplanetary magnetic-field, polar-cap arcs, theta-aurora, convection, patterns, transpolar arc, aligned currents, northward imf, precipitation, ionosphere, rotation
Fusion, Plasma and Space Physics
IdentifiersURN: urn:nbn:se:kth:diva-18814ISI: 000270321600001ScopusID: 2-s2.0-79952299798OAI: oai:DiVA.org:kth-18814DiVA: diva2:336861
QC 201005252010-08-052010-08-052012-03-20Bibliographically approved