The polar cusp: Optical and particle characteristics-dynamics

• Main Authors: Sandholt,P.E., Egeland,A., Asheim,S., Lybekk,B., Hardy,D.A.
• Format: Report
• Language: English
• Published: Institute of Physics, University of Oslo/Institute of Physics, University of Oslo/Institute of Physics, University of Oslo/Institute of Physics, University of Oslo/Air Force Geophysics Laboratory, Hanscom Air Force Base 1985
• Subjects: Norway; Svalbard; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1805; http://id.nii.ac.jp/1291/00001805/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1805&item_no=1&attribute_id=18&file_no=1

Photometric observations from two stations on Svalbard, Norway, have been used to map the location and dynamics of polar cusp auroras. Coordinated observations of low-energy electron precipitation from satellite HILAT and optical observations from the ground are discussed. Cases are presented showing the dynamical behaviour of cusp auroras and the local magnetic field related to changes in the interplanetary magnetic field (IMF) and irregularities in the solar wind plasma. Dynamical phenomena with different time scales are studied. South- and northward expansions of the midday sector of the auroral oval are discussed in relation to IMF variations and geomagnetic substorm activity. Intensifications and rapid poleward motions of discrete auroral structures in the cusp region are shown to be associated with local Pi-type magnetic pulsations, each event lasting a few minutes. These small-scale dynamical phenomena are discussed in relation to different models of plasma penetration across the dayside magnetopause, from the magnetosheath to the polar cusp region of the magnetosphere.