Abstract
Abstract. Joint observations of the all-sky camera at Resolute Bay (Nunavut, Canada) and the Polar Dual Auroral Radar Network (PolarDARN) HF radars at Rankin Inlet and Inuvik (Canada) are considered to establish radar signatures of poleward moving polar cap arcs "detaching" from the auroral oval. Common features of the events considered are enhanced power or echo occurrence in the wake of the arcs and enhanced spectral width of these echoes. When the arcs were oriented along some of the radar beams, velocity reversals at the arc location were observed with the directions of the arc-associated flows corresponding to a converging electric field. For the event of 9 December 2007, two arcs were poleward progressing almost along the central beams of the Inuvik radar at the speed close to the E × B drift of the bulk of the F-region plasma as inferred from HF Doppler velocities and from independent measurements by the Resolute Bay ionosonde. In global-scale convection maps inferred from all Super Dual Auroral Radar Network (SuperDARN) radar measurements, the polar cap arcs were often seen close to the reversal line of additional mesoscale convection cells located poleward of the normal cells related to the auroral oval.
Highlights
The Super Dual Auroral Radar Network (SuperDARN) HF radars have been very useful in studying various high-latitude phenomena (Chisham et al, 2007)
We focus on the arcs’ and their radar counterparts’ progression speeds and the E × B drifts that we infer from optical measurements, radar Doppler velocities and CADI ionosonde drift measurements at Resolute Bay
The Inuvik and Rankin Inlet PolarDARN HF radar measurements were combined with all-sky camera observations at Resolute Bay to investigate radar signatures of, and the plasma flows around, the polar cap arcs
Summary
The Super Dual Auroral Radar Network (SuperDARN) HF radars have been very useful in studying various high-latitude phenomena (Chisham et al, 2007). One area of research that has not been thoroughly addressed is plasma flows around bright optical forms. This is in contrast to VHF and UHF coherent radar E-region studies Uspensky et al (2001) gave an example of the Hankasalmi SuperDARN radar echo detection ∼100–200 km equatorward of an evening arc drifting equatorward. Seran et al (2009) investigated another single event, with limited Hankasalmi radar echo coverage around a weak auroral zone arc. Higher echo occurrence around the arcs would have been helpful in making more comprehensive conclusions
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