HR: 1330h
AN: SM12A-1191    [PDF]
TI: Dayside Auroral Morphology During Southeast IMF Orientation:Spatial Structure and its Implications for Magnetopause Reconnection
AU: Sandholt, P E
EM: p.e.sandholt@fys.uio.no
AF: Department of Physics, University of Oslo, Sem Saelands vei 24, Blindern, Oslo, 0316 Norway
AU: * Farrugia, C J
EM: charlie.farrugia@unh.edu
AF: Space Science Center, University of New Hampshire, 39 College Road, Durham, NH NH 03824 United States
AB: In a case study we elaborate on the spatial structure of the dayside aurora within 0800-1600 MLT and discuss its implications for magnetopause reconnection topology. The detailed 2D auroral morphology is obtained from continuous ground observations at Ny {\AA}lesund (76$^\circ$ MLAT), Svalbard during days when the interplanetary magnetic field (IMF) was oriented in the southeast direction ($B_y > 0$; $B_z < 0$). The major auroral features consist of sequential activations of latitudinally separated, sunward moving, arcs/bands (dayside BPS precipitation) in the prenoon (0800-1100 MLT) and postnoon (1200-1600 MLT) sectors which are separated by a deep minimum in activity/intensity within the 1100-1200 MLT sector. The latter ``midday gap'' aurora is attributed to the presence of component, steady state reconnection at the subsolar magnetopause where the stagnant magnetosheath flows lead to field-aligned currents (FAC) which are of only moderate intensity. The much more active and intense aurorae in the prenoon (0800-1100 MLT) and postnoon (1200-1600 MLT) sectors originate in magnetopause reconnection events that are initiated well away from the subsolar point, presumably in the form of antiparallel merging taking place near-simultaneously at high magnetopause latitudes in the southern/prenoon and northern/postnoon hemispheres, respectively, where the stronger boundary layer flow shears give rise to more intense FACs and aurorae.
DE: 2407 Auroral ionosphere (2704)
DE: 2724 Magnetopause, cusp, and boundary layers
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting