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We present results from a coordinated camera and radar study of the auroralionosphere conducted during March of 2006 from Poker Flat, Alaska. Thecampaign was conducted to coincide with engineering tests of the firstquarter installation of the Poker Flat Incoherent Scatter Radar (PFISR). On31 March 2006, a moderately intense auroral arc, (~10 kR at 557.7 nm),was located in the local magnetic zenith at Poker Flat. Duringthis event the radar observed 7 distinct periods of abnormally largebackscattered power from the F-region. These were only observed in thefield-aligned radar beam, and radar spectra from these seven times shownaturally enhanced ion-acoustic lines (NEIALs), the first observed withPFISR. These times corresponded to (a) when the polar cap boundary of theauroral oval passed through the magnetic zenith, and (b) when small-scalefilamentary dark structures were visible in the magnetic zenith. The presenceof both (a) and (b) was necessary for their occurrence. Soft electronprecipitation occurs near the magnetic zenith during these same times. Theelectron density in the vicinity where NEIALs have been observed by previousstudies is roughly between 5 and 30×10<sup>10</sup> m<sup>−3</sup>. Broad-bandextremely low frequency (BBELF) wave activity is observed in situ bysatellites and sounding rockets to occur with similar morphology, duringactive auroral conditions, associated with the poleward edge of the auroraand soft electron precipitation. The observations presented here suggestfurther investigation of the idea that NEIALs and BBELF wave activity aredifferently-observed aspects of the same wave phenomenon. If a connectionbetween NEIALs and BBELF can be established with more data, this couldprovide a link between in situ measurements of downward current regions(DCRs) and dynamic aurora, and ground-based observations of dark auroralstructures and NEIALs. Identification of in situ processes, namely waveactivity, in ground-based signatures could have many implications. Onespecific example of interest is identifying and following the temporal andspatial evolution of regions of potential ion outflow over large spatial andtemporal scales using ground-based optical observations

PFISR nightside observations of naturally enhanced ion acoustic lines, and their relation to boundary auroral features