Solar windmagnetosphere-ionosphere coupling: an event study based on Freja data

Solar windmagnetosphere-ionosphere coupling : an event study based on Freja data

QC 20100525 QC 20111027
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.

Eriksson, StefanKTH,Alfvénlaboratoriet,Rymd- och plasmafysik(Swepub:kth)- (author)
Cumnock, Judy A.KTH,Alfvénlaboratoriet,Rymd- och plasmafysik(Swepub:kth)u1qhxemy (author)
Yamauchi, M. (author)
Clemmons, J. H. (author)
Marklund, Göran T.KTH,Alfvénlaboratoriet,Rymd- och plasmafysik(Swepub:kth)u1yq52h6 (author)
Lindqvist, Per-ArneKTH,Alfvénlaboratoriet,Rymd- och plasmafysik(Swepub:kth)u1yukyk9 (author)
Karlsson, TomasKTH,Alfvénlaboratoriet,Rymd- och plasmafysik(Swepub:kth)u154ti5p (author)
Lundin, R. (author)
KTHAlfvénlaboratoriet (creator_code:org_t)

In:Journal of Atmospheric and Solar-Terrestrial Physics: Elsevier BV66:5, s. 375-3801364-68261879-1824

By the author/editor: Blomberg, Lars G ...; Eriksson, Stefan; Cumnock, Judy A.; Yamauchi, M.; Clemmons, J. H.; Marklund, Göran ...; show more...; Lindqvist, Per-A ...; Karlsson, Tomas; Lundin, R.; show less...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Earth and Relate ...; and Geochemistry

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