Ionospheric ion upwelling in the wake of flux transfer events at the dayside magnetopause

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Lockwood, Mike ; Smith, M. F. ; Farrugia, C. J. ; Siscoe, G. L. (1988)
  • Publisher: American Geophysical Union
  • Related identifiers: doi: 10.1029/JA093iA06p05641
  • Subject:
    arxiv: Physics::Plasma Physics | Physics::Space Physics

The effects of flux transfer events (FTE) on the dayside auroral ionosphere are studied, using a simple twin-vortex model of induced ionospheric plasma flow. It is shown that the predicted and observed velocities of these flows are sufficient to drive nonthermal plasma in the F region, not only within the newly opened flux tube of the FTE, but also on the closed, or "old" open, field lines around it. In fact, with the expected poleward neutral wind, the plasma is more highly nonthermal on the flanks of, but outside, the open flux tube: EISCAT observations indicate that plasma is indeed driven into nonthermal distributions in these regions. The nonthermal plasma is thereby subject to additional upforce due to the resulting ion temperature anisotropy and transient expansion due to Joule heating and also to ion accelerations associated with the FTE field aligned current system. Any upflows produced on closed field lines in the vicinity of the FTE are effectively bunched-up in the "wake" of the FTE. Observations from the AMPTE-UKS satellite at the magnetopause reveal ion upflows of energy ∼100 eV flowing out from the ionosphere on closed field lines which are only found in the wake of the FTE. Such flows are also only found shortly after two, out of all the FTEs observed by AMPTE-UKS. The outflow from the ionosphere is two orders of magnitude greater than predicted for the "classical" polar wind. It is shown that such ionospheric ion flows are only expected in association with FTEs on the magnetopause which are well removed from the sub-solar point-either towards dusk or, as in the UKS example discussed here, towards dawn. It is suggested that such ionospheric ions will only be observed if the center of the FTE open flux tube passes very close to the satellite. Consequently, we conclude the ion upflows presented here are probably driven by the second of two possible source FTEs and are observed at the satellite with a lag after the FTE which is less than their time-of-flight.
  • References (48)
    48 references, page 1 of 5

    Barakat, A. R., R. W. Schunk, and J.-P. St.- Maurice, Monte Carlo calculations of the 0+ velocity distribution in the auroral ionosphere, J. Geophys. Res., 88, 3237-3241, 1983.

    Barakat, A. R., and R. W. Schunk, Effect of hot electrons on the polar wind, J. Geophys. Res., 89, 9771-9783 (1984).

    Chaloner, C. P., . D. R. Lepine, D. S. Hall, D. A. Bryant, W. Studeman, B. Wilken, G. Kremser, F. Sraas, K. Branstad, J. F. Fennell, B. Blake, R. Koga, and R. Lundin, Tne formation of boundary layers by the entry of low energy electrons and energetic ions into the earth's magnetosphere, Proceedings of 21st ESLAB Symposium, Bolkesjo, Norway, Eur. Space Agency Spec. Publ. ESA SP-275, 51-56, 1987.

    Coates, A. J., J. A. Bowles, R. A. Gowen, B. K. Hancock, A.D. Johnstone, and S. J. Kellock, The AMPTE UKS three-dimensional ion experiment, IEEE Trans. Geosci. Remote Sens., GE-23, 287-292, 1 985.

    Cowley, S. W. H., Evidence for the occurrence and importance of reconnection between the Earth's magnetic field and the interplanetary field, in Magnetic Reconnection in Space and Laboratory Plasmas, Geophys. Monogr. Ser., vol. 30, edited by E. W. Hones, Jr., pp.375- 378, AGU, Washington, D. C., 1984.

    Darwin, C., Note on hydrodynamics, Proc. Cambridge Philos. Soc., 49, 342-354, 1953.

    Dusenbery, P. B., and L. R. Lyons, Generation of ion-conic distribution by upgoing ionospheric electrons, J. Geophys. Res., 86, 7627-7638, 1981.

    Farmer, A. D., M. Lockwood, T. J. Fu!ler-Rowell, K. Suvanto, and U. P. Lovhaug, Model predictions of the occurrence of non-Maxwellian plasmas, and analysis of their effects EISCAT data, J. Atmos. Terr. Phys., 1 988.

    in press, region in flux transfer events: Tneory, Planet. Space Sci., 35, 227-240, 1987.

    Farrugia, C. J., R. P. Rijnbeek, M. A. Saunders, D. J. Southwood, D. J. Rodgers, M. F. Smith, C. P. Chaloner, D. S. Hall, P. J. Christiansen, and L. J. C. Woolliscroft, A multi-instrument study of flux transfer event structure, J. Geophys. Res., in press, 1988.

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