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The meridional motions of the CUTLASS HF and STARE VHF coherentechoes, IMAGE equivalent electrojet currents, and IRIS absorptionpatches during the postnoon/early-evening event of 14February 2000 are presented. The motions were found to besynchronous, to a first approximation, for all instruments. Thetemporal correlation between motions in the radar and magnetometerdata was exceptionally good, although spatially the areas with theE-region backscatter and most intense equivalent currents were notcoincident, with the HF (VHF) echoes being shifted 100–200km(20–50km) equatorward (poleward). The meridional motions of theradar echoes and electrojet currents appeared to be controlled bythe IMF Bz changes; the meridional propagation direction wasequatorward (poleward) during the intervals when the IMF wassouthward (northward), with one exception when the polewardprogression continued after the IMF southward turning. We relatethe observed meridional motion patterns to the polar capexpansion/contraction during variable IMF conditions and discussthe relative importance of two types of processes: the daysidereconnection and IMF-triggered substorms. We also investigate theirregularity Doppler velocity for the STARE (144MHz) and CUTLASS(12MHz) observations at large flow angles in the context of theeastward and westward electrojet systems. We show that the 144-MHzDoppler velocity is determined by a combination of two factors:the sense of electrojet currents and the aspect angle conditionswithin the STARE field of view. Finally, the behavior of smalldayside enhancements of the IRIS absorption (up to 0.5dB at 38.2MHz)accompanying the radar echoes and electrojet currents isexamined. Since the velocity of the meridional displacements wasclose to that of the poleward/equatorward progressing intensecurrents, it is suggested that the absorption patches observedduring the event were related to the heating of the E-regionplasma by the unstable plasma waves in the regions of enhancedelectric fields. Key words. Ionosphere (auroral ionosphere; electric fieldsand currents; plasma convection

Meridional motions of the afternoon radar aurora, auroral electrojets, and absorption patches under variable IMF conditions