Multi-instrument study of footprints of magnetopause reconnection in the summer ionosphere

Abstract

Abstract. Results are presented from a multi-instrument investigation of the signatures of equatorial reconnection in the summer, sunlit ionosphere. Well-established ion dispersion signatures measured during three DMSP satellite passes were used to identify footprints in ionospheric observations made by radio tomography, and both the EISCAT ESR and mainland radars. Under the prevalent conditions of southward IMF with the Bz component increasing in magnitude, the reconnection footprint was seen to move equatorward through the ESR ®eld-of-view. The most striking signature was in the electron temperatures of the F2 region measured by the EISCAT mainland radar that revealed signi®cantly enhanced temperatures with a steep equatorward edge, in general agreement with the leading edge of the ion dispersion. It is suggested that this sharp transition in the electron temperature may be an indicator of the boundary, mapping from the reconnection site, between closed geomagnetic ®eld lines and those opened along which magnetosheath ions precipitate.

Polar patches observed by ESR and their possible origin in the cusp region

“…However, the observations presented also showed signatures in the plasma that are characteristic of equatorial reconnection. For example, DMSP satellite particle¯ux measurements revealed ion dispersion and cusp precipitation (Newell and Meng, 1988) while the EISCAT electron temperatures indicated soft precipitation within the region of dispersion with its sharp equatorward edge (Pryse et al, 2000). Moreover, electron densities within the precipitation region at the northernmost part of the EISCAT mainland scan starting at 0820 UT (Fig.…”

The dayside high-latitude trough under quiet geomagnetic conditions: Radio tomography and the CTIP model

“…Radio tomography (Kunitsyn and Tereshchenko, 2003;Pryse, 2003 and references therein) is a relatively new technique for imaging the spatial distribution of the ionospheric plasma over extended height-versus-latitude planes. It is particularly adept at imaging the plasma distribution in regions of density troughs (Andreeva et al, 1990;Kersley et al, 1997) coverage of the ionosphere at all Universal Times, seasons, geomagnetic and solar conditions.…”

EISCAT Svalbard radar observations of ionospheric signatures of magnetopause reconnection during a changing IMF Bz polarity

“…The location of the EISCAT Svalbard Radar (ESR) at 78.2 • N is more favourable for observations in the vicinity of the cusp. Signatures of equatorial reconnection have been seen by this radar when observing along the magnetic field (Pryse et al, 2000a) and spatial structures of increased electron temperatures within the reverse ion-dispersion of lobe reconnection have been identified in a multi-instrument investigation of the ionosphere under steady northward IMF (Pryse et al, 2000b). The current paper develops the use of the ESR to investigate the spatial signatures of reconnection processes in the ionospheric plasma.…”

“…Signatures of equatorial reconnection have been identified by the EISCAT mainland radar, when it was observing north of the radar site (Lockwood 1993). The EIS-CAT radar has also been used to observe spatial structures of enhanced electron temperature in regions that map to satellite ion dispersion signatures (Pryse et al, 2000a). These increased temperatures extended through the topside ionosphere to the F-layer peak and had a steep latitudinal gradient on their equatorward edge.…”