© European Geosciences Union 2003
The location and rate of dayside reconnection during an interval of southward interplanetary magnetic field
1British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
2Center for Space Sciences, Univ. of Texas at Dallas, Richardson, Texas, USA
3LPCE/CNRS, 3A Av. De la Recherche Scientifique, 45071 Orleans Cedex, France
Abstract. 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 RE 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.
Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetosphere-ionoshere interactions) – Space plasma physics (magnetic reconnection)