Magnetic Pulsations in the Period Range from 40 to 170 Seconds Observed at Synchronous Orbit: Comparison of Satellite and Ground Data

• Main Authors: Tohru Sakurai, Yutaka Tonegawa, Yoshio Kato
• Format: Report
• Language: English
• Published: Laboratory of Space Science, Tokai Universuty 1981
• Subjects: Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1130; http://id.nii.ac.jp/1291/00001130/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1130&item_no=1&attribute_id=18&file_no=1

Monochromatic sinusoidal oscillations in the period range from 40 to 170s were frequently observed by a synchronous satellite, ATS-6,in August of 1975. During the observation period the satellite was located at 35°east longitude and close to the geomagnetic equatorial plane. The present paper concerns with an examination on wave characteristics of these monochromatic sinusoidal oscillations and on an oscillation mechanism by analyzing numerous wave events observed by ATS-6. The results indicate that oscillations show a clear local time variation in the period, shorter in the morning and longer in the evening. With regard to an oscillation mechanism our conclusion strongly supports a hypothesis that the second harmonic resonance oscillation of standing Alfven wave is most probably an oscillation mode near the synchronous orbit at 6.6 earth radii. Another examination of the satellite and ground correlation of those waves indicates that there is a clear evidence of a rotation of the principal axis of the waves observed by the satellite and on the ground.