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Ann. Geophys., 20, 477-486, 2002
www.ann-geophys.net/20/477/2002/
© European Geosciences Union 2002
EISCAT Svalbard radar observations of ionospheric signatures of magnetopause reconnection during a changing IMF Bz polarity
S. E. Pryse1, A. M. Smith1,3, L. Kersley1, and I. W. McCrea2
1Department of Physics, University of Wales, Aberystwyth, SY23 3BZ, UK
2Rutherford Appleton Laboratory, Department of Space Science, Didcot, OX11 0QX, UK
3Now at DERA, Malvern, WR14 3PS, UK
Correspondence to: S. E. Pryse (sep@aber.ac.uk)
Abstract. Observations by the
EISCAT Svalbard radar are presented that show the response of the spatial
structure of the ionosphere in the dayside cusp region to a rotational trend in
the IMF clock angle. Over a period of one hour, the clock angle increased from
about 45° to some 150°, moving the likely location of the magnetopause
reconnection site from the high-latitude lobe to near the equatorial plane.
Increased topside electron temperatures measured by the ESR identified
footprints of the reconnection process. Temporal changes in the spatial
distribution of the temperature reflected the change from lobe to equatorial
reconnection. Discrete spatial enhancements in ion temperature were found
resulting from ion-neutral frictional heating in the fast flows where it was
likely that field lines were being convected from the reconnection locations.
The corresponding electron density structuring is interpreted in terms of the
particle precipitation, field-aligned currents and convection flows driven by
the IMF.
Key words. Ionosphere (ionosphere
– magnetosphere interactions; plasma temperature and density; polar
ionosphere)
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