Abstract
Abstract. Early in 1996, the latest of the European incoherent-scatter (EISCAT) radars came into operation on the Svalbard islands. The EISCAT Svalbard Radar (ESR) has been built in order to study the ionosphere in the northern polar cap and in particular, the dayside cusp. Conditions in the upper atmosphere in the cusp region are complex, with magnetosheath plasma cascading freely into the atmosphere along open magnetic field lines as a result of magnetic reconnection at the dayside magnetopause. A model has been developed to predict the effects of pulsed reconnection and the subsequent cusp precipitation in the ionosphere. Using this model we have successfully recreated some of the major features seen in photometer and satellite data within the cusp. In this paper, the work is extended to predict the signatures of pulsed reconnection in ESR data when the radar is pointed along the magnetic field. It is expected that enhancements in both electron concentration and electron temperature will be observed. Whether these enhancements are continuous in time or occur as a series of separate events is shown to depend critically on where the open/closed field-line boundary is with respect to the radar. This is shown to be particularly true when reconnection pulses are superposed on a steady background rate.
Highlights
The European incoherent-scatter (EISCAT) radars have been in operation in northern Scandinavia since 1983 (Rishbeth and Williams, 1985)
At 78.2°N, 15.82°E, the EISCAT Svalbard Radar (ESR) is in an ideal position to study the dynamics of the upper atmosphere in the polar cusp region and the dayside polar cap (Cowley et al, 1990)
These regions are threaded by field lines which have been reconnected with the interplanetary magnetic field (IMF) relatively recently
Summary
The European incoherent-scatter (EISCAT) radars have been in operation in northern Scandinavia since 1983 (Rishbeth and Williams, 1985). At 78.2°N, 15.82°E, the EISCAT Svalbard Radar (ESR) is in an ideal position to study the dynamics of the upper atmosphere in the polar cusp region and the dayside polar cap (Cowley et al, 1990) These regions are threaded by field lines which have been reconnected with the interplanetary magnetic field (IMF) relatively recently. The output from a time-dependent, self-consistent auroral precipitation model (Palmer, 1995) was used to model the spatial and temporal distribution of 630-nm atomic oxygen emission in response to pulsed magnetopause reconnection In this way, it was possible to simulate how such events would appear to a meridian scanning photometer in the cusp region. For the illustrative purpose of this paper we will limit ourselves to two cases with square wave pulses in reconnection rate, namely fully pulsed reconnection and reconnection pulses during which the rate is twice the steady background value between the pulses
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