HR: 0800h
AN: SM51C-0383    [Abstracts]
TI: Comparison between ionospheric convection vortices and the associated equivalent currents
AU: * Liang, J
EM: liang@dansas.usask.ca
AF: ISAS, Dept. of Physsics Univ. of Saskatchewan, Saskatoon, SK S7N 5E2 Canada
AU: Benkevitch, L
EM: benkevitch@dansas.usask.ca
AF: ISAS, Dept. of Physsics Univ. of Saskatchewan, Saskatoon, SK S7N 5E2 Canada
AU: Sofko, G J
EM: sofko@dansas.usask.ca
AF: ISAS, Dept. of Physsics Univ. of Saskatchewan, Saskatoon, SK S7N 5E2 Canada
AU: Koustov, A V
EM: sasha.koustov@usask.ca
AF: ISAS, Dept. of Physsics Univ. of Saskatchewan, Saskatoon, SK S7N 5E2 Canada
AB: The equivalent current pattern derived from CANOPUS, NRCAN/GSC and MACCS magnetometers has been compared with the ionospheric convection pattern observed by SuperDARN HF radars. The discrepancies between the equivalent convection (EQC) and the SuperDARN-observed convection (SDC) patterns are explained in terms of the effect of day-night photoionization conductance gradient and the coupling between field-aligned currents (FACs) and ionospheric conductances. In particular, the agreement between the EQC and SDC patterns is usually worse for a counterclockwise convection vortex than for a clockwise cell, but a consistent pattern of discrepancy for counterclockwise convection vortices has been found. We suggest that the discrepancies are due to a downward FAC-conductance coupling process. Since the counterclockwise vortices and clockwise vortices occur predominantly in the dawn and dusk sectors, respectively, in accordance with the usual 2-cell global convection pattern, the asymmetry between the EQC and SDC patterns for counterclockwise vortices and clockwise vortices would naturally lead to a dawn-dusk asymmetry as well. This is revealed by a global statistical study of the deviation of direction between the magnetic equivalent convection and the SuperDARN convection in different time sectors and latitudes. In the dawn sector, the statistical results reveal that, at lower latitudes, the EQC direction deviation is slightly counterclockwise with respect to the SDC direction, whereas the deviation is significantly clockwise at high latitudes. These deviations are consistent with the discrepancy pattern for counterclockwise convection vortices, as found in the individual vortex event studies.
DE: 5734 Magnetic fields and magnetism
DE: 2463 Plasma convection
DE: 2708 Current systems (2409)
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting