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Title: Observations of reconnected flux tubes within the midaltitude cusp

Journal Article · · Journal of Geophysical Research; (United States)
 [1];  [2];  [3];  [4];  [5]
  1. Univ. of Texas, San Antonio (USA)
  2. Southwest Research Institute, San Antonio, TX (USA)
  3. Kyoto Univ. (Japan)
  4. Univ. of Iowa, Iowa City (USA)
  5. Univ. of Alabama, Huntsville (USA)

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 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 B{sub y} 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 are 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 Alfven waves.

OSTI ID:
5376357
Journal Information:
Journal of Geophysical Research; (United States), Vol. 95:A6; ISSN 0148-0227
Country of Publication:
United States
Language:
English