Space Sciences Directorate, NASA/GSFC, Greenbelt, MD

Evidence is presented that the WIND spacecraft observed particle and field signatures resulting from the footpoints of the magnetic cloud of October 18-19, 1995, reconnecting at a low altitude, between 1 and 5 solar radii. The observations include (i) an internal shock traveling approximately along the axis of the magnetic cloud, (ii) simple compression of the magnetic field consistent with the footpoint magnetic fields being thrust outwards at speeds much greater than the solar wind speed, (iii) an electron heat flux drop out occurring within minutes of the shock indicating a topological change resulting from disconnection from the solar surface and (iv) a very cold 6 keV proton beam resulting from reconnection and an associated monochromatic wave. We expect that, given observations of enough magnetic clouds, WIND and other spacecraft will see signatures similar to the ones reported here indicating reconnection. However, these observations require the spacecraft to be fortuitously positioned to observe the passing shock and other signatures and will therefore be associated with only a small fraction of magnetic clouds. Consistent with this, a few other magnetic clouds observed by WIND have been observed to possess internal shock waves.

J. Geophys. Res., submitted, 1999