Abstract
Abstract. Since the middle of 1995, an HF Doppler sounder has been running almost continuously in northern Norway, with the receiver at Ramfjordmoen and the transmitter at Seljelvnes. Concurrent operation of the EISCAT UHF radar in common programme (CP-1) mode has made it possible to study the ionospheric signature of a magnetospheric ULF wave. These are the first results of such wave signatures observed simultaneously in both instruments. It has been demonstrated that the observed Doppler signature was mainly due to the vertical bulk motion of the ionosphere caused by the electric field perturbation of the ULF wave and the first direct observational confirmation of a numerical simulation has been achieved. The wave, which was Alfvénic in nature, was detected by the instruments 8° equatorward of the broad resonance region. The implications for the deduced wave modes in the ionosphere and the mechanism producing the HF Doppler variations are discussed.Key words. Magnetosphere-ionosphere interactions · MHD waves and instabilities · Radio science · Ionospheric physics
Highlights
Ultra-low-frequency (ULF) waves are an important coupling mechanism between the magnetosphere and the ionosphere since they transfer both energy and momentum
This paper presents the ®rst observations made by Doppler Pulsation Experiment (DOPE) in conjunction with the European Incoherent Scatter (EISCAT) UHF radar
We present data associated with a ULF wave which occurred on 13 February 1996 and was detected simultaneously in the ionosphere by the DOPE sounder and the EISCAT UHF radar and at the ground by IMAGE magnetometer stations
Summary
Ultra-low-frequency (ULF) waves are an important coupling mechanism between the magnetosphere and the ionosphere since they transfer both energy and momentum. These interactions are most signi®cant in Correspondence to: D. Yeoman et al, 1990) for magnetospheric magnetohydrodynamic (MHD) wave modes and controls the transfer of energy and momentum. It modi®es the magnetospheric wave signature, leading to rotation and attenuation of the wave magnetic signature detected on the ground The ionospheric signature of ULF waves is an important topic of study
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