Simultaneous optical and radar signatures of poleward-moving auroral forms

A. Thorolfsson (1) , Jean-Claude Cerisier (1, 2) , M. Lockwood (3, 4) , P. E. Sandholt (5) , Catherine Senior (1) , M. Lester (6)

1 CETP - Centre d'étude des environnements terrestre et planétaires
2 UPMC - Université Pierre et Marie Curie - Paris 6
3 RAL Space - Space Science and Technology Department [Didcot]
4 School of Physics and Astronomy [Southampton]
5 Department of Physics [Oslo]
6 Department of Physics and Astronomy [Leicester]

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.

Domaines: Océan, Atmosphère; Sciences de la Terre

A. Thorolfsson, Jean-Claude Cerisier, M. Lockwood, P. E. Sandholt, Catherine Senior, et al.. Simultaneous optical and radar signatures of poleward-moving auroral forms. Annales Geophysicae, 2000, 18 (9), pp.1054-1066. ⟨hal-00329159⟩