Polar cap study during northward interplanetary magnetic field on 19 January 1998

• Published in: Physics of Plasmas
• Main Authors: Slinker, S. P., Fedder, J. A., McEwen, D. J., Zhang, Y., Lyon, J. G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: AIP Publishing 2001
• Subjects: Condensed Matter Physics; Eureka; North Magnetic Pole
• Online Access: http://dx.doi.org/10.1063/1.1355680; https://pubs.aip.org/aip/pop/article-pdf/8/4/1119/12421230/1119_1_online.pdf

The interplanetary magnetic field (IMF) was northward for an extended period on 19 January 1998. This caused the open polar cap of the ionosphere to become very small and the auroral emission to move poleward. The auroral emission at 630 nm was observed by the meridian scanning photometer located at Eureka near the north magnetic pole. Effects of changes in sign of the dawn–dusk component of the IMF were also observed. A magnetohydrodynamic simulation model of the magnetosphere and ionosphere was used to study these events. The model was driven using data from the Wind and IMP-8 spacecraft. The simulation results show a very small open polar cap indicating that the magnetosphere is nearly closed. Moreover, in response to the shift from dawnward to duskward IMF, a narrow strip of closed field breaks off from the dawn boundary and convects across the polar cap and into the dusk boundary.