Spatial Structure of High-Latitude Pc5 Pulsations Via SuperDARN Data

Pavlo V PONOMARENKO1, Colin L WATERS1, John C SAMSON2, Murray D SCIFFER1,
and Brian J FRASER1
1University of Newcastle, Australia
2University of Alberta, Canada

HF and VHF radars present a convenient tool for the ULF wave diagnostics at ionospheric heights [1, 2]. They provide a relatively high spatial resolution D r£ 30-40 km in comparison with the ground-based magnetometers, which cannot resolve structures smaller then D r» 200 km due to the so-called spatial integration effect [3, 4]. Although a general agreement between the radar and magnetometer data is usually found, on some occasions they are quite different one from another [5]. This demands a further progress in understanding of the ionosphere effect on the ULF wave propagation. In this work we used data from the Saskatoon SuperDARN radar to restore horizontal distributions of frequency, amplitude, and phase of Pc5 pulsations, which were also observed over the CANOPUS magnetometer array. Using a simple model we attempted to show that the observed discrepancies between the ionospheric and ground pulsation characteristics could be explained by the spatial integration effect.

  1. Walker, A.D.M., R.A.Greenwald, W.F.Stuart, and C.A.Green, STARE auroral radar observations of Pc5 geomagnetic pulsations, JGR, Vol.84, No.A7, 3373, 1979.

  2. Walker, A.D.M., J.M.Ruohoniemi, K.B.Baker, and R.A.Greenwald, Spatial and temporal behavior of ULF pulsations observed by the Goose Bay HF radar, JGR, Vol.97, No.A8, 12,187, 1992.

  3. Hughes, W.J., and D.J.Southwood, An illustration of modification of geomagnetic pulsation structure by the ionosphere, JGR, Vol.81, No.19, 3241, 1976.

  4. Poulter, E.M., and W.Allan, Transient ULF pulsation decay rates observed by ground based magnetometers: the contribution of spatial integration, Planet. Space. Sci., Vol.33, No.6, 607, 1985.

  5. Ziesollek, C.W.S., F.R.Fenrich, J.C.Samsom, and D.R.McDiarmid, Pc5 field line resonance frequencies and structure observed by SuperDARN and CANOPUS, JGR, Vol.103, No.A6, 11,771, 1998.

Session Index Proceedings Index