Detailed Dayside Auroral Morphology as a Function of Local Time for southeast IMF Orientation: Implications for Solar Wind-Magnetosphere Coupling

Abstract

In two case studies we elaborate on spatial and temporal structures of the dayside aurora within 08:00-16:00 magnetic local time (MLT) and discuss the relationship of this structure to solar wind-magnetosphere interconnection topology and the different stages of evolution of open field lines in the Dungey convection cycle. The detailed 2-D auroral morphology is obtained from continuous ground observations at Ny Alesund (76 deg magnetic latitude (MLAT)), Svalbard during two days when the interplanetary magnetic field (IMP) is directed southeast (By >0; Bz<0). The auroral activity consists of the successive activations of the following forms: (i) latitudinally separated, sunward moving, arcs/bands of dayside boundary plasma sheet (BPS) origin, in the prenoon (08:0O-11:00 MLT) and postrioon (l2:00-16:00 MLT) sectors, within 70-75 deg MLAT, (ii) poleward moving auroral forms (PMAFs) emanating from the pre- and postnoon brightening events, and (iii) a specific activity appearing in the 07:00-10:00 MLT/75-80 deg MLAT during the prevailing IMP By>0 conditions. The pre- and postnoon activations are separated by a region of strongly attenuated auroral activity/intensity within the 11:0O-l2:00 MLT sector, often referred to as the midday gap aurora. The latter aurora is attributed to the presence of component reconnection at the subsolar magnetopause where the stagnant magnetosheath flow lead to field-aligned currents (PACs) which are of only moderate intensity. The much more active and intense aurorae in the prenoon (07:0O-11:00 MLT) and postnoon (12:00-16:00 MLT) sectors originate in magnetopause reconnection events that are initiated well away from the subsolar point. The high-latitude auroral activity in the prenoon sector (feature iii) is found to be accompanied by a convection channel at the polar cap boundary. The associated ground magnetic deflection (DPY) is a Svalgaard-Mansurov effect.

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Document Details

Document Type
Technical Report
Publication Date
Nov 03, 2004
Accession Number
ADA431366

Entities

People

  • C. J. Farrugia
  • P. E. Sandholt
  • W. F. Denig

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Advanced Electronics
  • Space

DTIC Thesaurus Topics

  • Air Force Research Laboratories
  • Boundaries
  • Boundary Layer
  • Case Studies
  • Convection
  • Dynamic Pressure
  • Geometry
  • High Latitudes
  • Latitude
  • Magnetic Fields
  • Magnetosphere
  • Momentum Transfer
  • Orientation (Direction)
  • Polar Cap
  • Solar Wind
  • Spacecraft
  • Two Dimensional

Readers

  • Space/Atmospheric Physics.