A comparison of EISCAT and HF Doppler observations of a ULF wave

• Main Authors: Wright, D. M., Yeoman, T. K., Davies, J. A.
• Other Authors: Department of Physics and Astronomy Leicester, University of Leicester
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 1998
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Norway; Ramfjordmoen; Seljelvnes; EISCAT; Northern Norway
• Online Access: https://hal.science/hal-00316447; https://hal.science/hal-00316447/document; https://hal.science/hal-00316447/file/angeo-16-1190-1998.pdf

International audience 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.