HIGH SPATIAL AND TEMPORAL RESOLUTION OBSERVATIONS OF THE IONOSPHERIC CUSP

The Halley PACE HF radar has been operated in a new mode to provide ve ry high time (10 s) and space (15 km) resolution measurements of the i onospheric signatures of the cusp and the low-latitude boundary layer. The first data show that the ionospheric signature of flux transfer e vents occur up to 300 km equatorward of regions showing the HF charact eristics of the ionospheric cusp. Whilst larger flux transfer events a re seen, on average, every 7 min, many much smaller and short-duration events have been identified. On one occasion DMSP data have been used to show that at least four flux transfer events are occurring simulta neously at the edge of the cusp over 2 h of MLT. There is strong, but not conclusive evidence, that reconnection at the magnetopause is both intermittent and patchy. These data also suggest that flux transfer e vents can be a significant contributor to the cross-polar cap potentia l.