Combined radar and optical observations of auroral fine scale structures in the cusp region

We present initial results from a coordinated study of auroral fine scale structures in the polar ionosphere near magnetic noon, using the EISCAT Svalbard Radar (ESR) and the University of Calgary portable auroral imager (PAI), in a campaign in Longyearbyen, from 10th - 19th of January, 2002. The European incoherent scatter radr system (EISCAT) located in northern Scandinavia has for long detected strong anomalous echoes, which earlier where thought of as coherent reflections from overpassing satellites. It has recently become clear that a part of these echoes stem from localized instabilities arising in the ionosphere, however, a fully satisfactory physical interpretation has yet to be found. We will present data from a period when naturally enhanced ion spectra were detected by the ESR running in an interferometer mode, which allows significantly higher temporal and spatial resolution than from standard experiments. Simultaneous as these where detected by the ESR, the parallel pointing PAI observed very dynamical auroral rays in, and adjacent to, the radar beam. The high resolution optical data from PAI helps to clarify under which geophysical conditions the natural enhanced ion spectra observed with the ESR occur.