Reconnection event at the dayside magnetopause on January 10, 1997

Geotail was at the magnetopause near the sub-solar point when the magnetic cloud struck the earth's magnetosphere on January 10, 1997. Reconnection between the southward IMF and the magnetospheric field lines occurred at the dayside magnetopause as observed by Geotail. The signatures of the reconnection were, i) accelerated plasma flow from the reconnection site which reached up to 500 km/s, ii) ion heating through the reconnection process, and iii) a velocity filter effect seen in the ion distribution function in the magnetosheath boundary layer. This reconnection may be related to the large substorm onset observed at geosynchronous orbit.