Dynamics Explorer 1 observations within the midaltitude polar cusp provide indirect evidence of reconnected flux tubes (RFT) envisioned to be extensions of the flux transfer events reportedly found near the magnetopause. In this study, low-energy plasma, high-energy plasma, magnetic fields, and electric fields were used to identify the signatures of reconnected flux tubes in the midaltitude cusp. Inside isolated flux tubes, low-energy plasma was observed to be transferred from the magnetosheath to the magnetosphere, and relatively hot plasma was observed to be transferred from the magnetosphere to the magnetosheath. The cool magnetosheath plasma and the relatively hot magnetospheric plasma shared the same magnetic flux tube. The RFT signature is most easily identified in electron and ion energy fluxes plotted versus time for all pitch angles. The electron signature of an RFT is characterized by a drop in energy at the upper side of the energy band. The ion energy signature is similar to the electron signature except the ions form distinct Vs within the RFTs which differ from Vs outside the RFTs by the fact that the thickness of the lines forming the sides of the Vs is thinner inside the RFTs in comparison to that outside, and the height of these Vs is shorter inside the RFTs.

The characteristics of spatial scale, time duration, and frequency of occurrence between flux transfer events and midaltitude cusp reconnected flux tubes are consistent, although they differ in the direction of motion. However, the merging cell topology and the interplanetary magnetic field By effect can explain this difference. Larger-scale (space and time) events can be explained by motion of the cusp resulting from a quasi-steady reconnection process. The field-aligned currents associated with reconnected flux tubes at midaltitudes within the cusp are consistent with twisting of magnetic field lines and with closure by Pedersen currents. It is possible that what appear to be field-aligned currents closing by Pedersen ionospheric currents may also be interpreted as currents carried by Alfv¿n waves. ¿ American Geophysical Union 1990