The location and rate of dayside reconnection during an interval of southward interplanetary magnetic field

• Main Authors: M. Pinnock, G. Chisham, I. J. Coleman, M. P. Freeman, M. Hairston, J.-P. Villain
• Format: Article
• Language: English
• Published: Copernicus Publications 2003-07-01
• Series: Annales Geophysicae
• Online Access: https://www.ann-geophys.net/21/1467/2003/angeo-21-1467-2003.pdf
• ISSN: 0992-7689; 1432-0576

Using ionospheric data from the SuperDARN radar network and a DMSP satellite we obtain a comprehensive description of the spatial and temporal pattern of day-side reconnection. During a period of southward interplanetary magnetic field (IMF), the data are used to determine the location of the ionospheric projection of the dayside magnetopause reconnection X-line. From the flow of plasma across the projected X-line, we derive the reconnection rate across 7 h of longitude and estimate it for the total length of the X-line footprint, which was found to be 10 h of longitude. Using the Tsyganenko 96 magnetic field model, the ionospheric data are mapped to the magnetopause, in order to provide an estimate of the extent of the reconnection X-line. This is found to be ~ 38 R_E in extent, spanning the whole dayside magnetopause from dawn to dusk flank. Our results are compared with previously reported encounters by the Equator-S and Geotail spacecraft with a reconnecting magnetopause, near the dawn flank, for the same period. The SuperDARN observations allow the satellite data to be set in the context of the whole magnetopause reconnection X-line. The total potential associated with dayside reconnection was ~ 150 kV. The reconnection signatures detected by the Equator-S satellite mapped to a region in the ionosphere showing continuous flow across the polar cap boundary, but the reconnection rate was variable and showed a clear spatial variation, with a distinct minimum at 14:00 magnetic local time which was present throughout the 30-min study period.<br><br><b>Key words. </b>Magnetospheric physics (magnetopause, cusp and boundary layers; magnetosphere-ionoshere interactions) – Space plasma physics (magnetic reconnection)