Articles | Volume 18, issue 9
Ann. Geophys., 18, 1054–1066, 2000

Special issue: IXe EISCAT

Ann. Geophys., 18, 1054–1066, 2000

  30 Sep 2000

30 Sep 2000

Simultaneous optical and radar signatures of poleward-moving auroral forms

A. Thorolfsson1, J.-C. Cerisier2,1, M. Lockwood3,4, P. E. Sandholt5, C. Senior1, and M. Lester6 A. Thorolfsson et al.
  • 1Centre d'étude des Environments Terrestre et Planétaires, 4 avenue de Neptune, 94107 Saint-Maur CEDEX, France
  • 2Université Pierre et Marie Curie, 4 place Jussieu, 75005 Paris, France
  • 3Department of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ, United Kingdom
  • 4Space Science Department, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, United Kingdom
  • 5Department of Physics, University, University of Oslo, P.O. Box 1048, Blindern, Norway
  • 6Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, United Kingdom
  • Correspondence to: A. Thorolfsson
  • e-mail:

Abstract. Dayside poleward moving auroral forms (PMAFs) were detected between 06:30 and 07:00 UT on December 16, 1998, by the meridian scanning photometer and the all-sky camera at Ny Ålesund, Svalbard. Simultaneous SuperDARN HF radar measurements permitted the study of the associated ionospheric velocity pattern. A good general agreement is observed between the location and movement of velocity enhancements (flow channels) and the PMAFs. Clear signatures of equatorward flow were detected in the vicinity of PMAFs. This flow is believed to be the signature of a return flow outside the reconnected flux tube, as predicted by the Southwood model. The simulated signatures of this model reproduce globally the measured signatures, and differences with the experimental data can be explained by the simplifications of the model. Proposed schemes of the flow modification due to the presence of several flow channels and the modification of cusp and region 1 field-aligned currents at the time of sporadic reconnection events are shown to fit well with the observations.

Key words: Ionosphere (auroral ionosphere; plasma convection) - Magnetospheric physics 
(magnetopause; cusp and boundary layers)

Special issue