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Observations of Pc5 micropulsation-related electric field oscillations in equatorial ionosphereA 54.95-MHz coherent backscatter radar, an ionosonde and the magnetometer located at Trivandrum in India (8.5 deg N, 77 deg E, 0.5 deg N dip angle) recorded large-amplitude ionospheric fluctuations and magnetic field fluctuations associated with a Pc5 micropulsation event, which occurred during an intense magnetic storm on 24 March 1991 (A(sub p) = 161). Simultaneous 100-n T-level fluctuations are also observed in the H-component at Brorfelde, Denmark (55.6 deg N gm) and at Narsarsuaq, Greenland (70.6 deg N gm). Our study of the above observations shows that the E-W electric field fluctuations in the E- and F-regions and the magnetic field fluctuations at Thumba are dominated by a near-sinusoidal oscillation of 10 min during 1730-1900 IST (1200-1330 UT), the amplitude of the electric field oscillation in the equatorial electrojet (EEJ) is 0.1-0.25 mV/m and it increases with height, while it is about 1.0 mV/m in the F-region, the ground-level H-component oscillation can be accounted for by the ionospheric current oscillation generated by the observed electric field oscillation in the EEJ and the H-component oscillations at Trivandrum and Brofelde are in phase with each other. The observations are interpreted in terms of a compressional cavity mode resonance in the inner magnetosphere and the assoicated ionospheric electric field penetrating from high latitudes to the magnetic equator.
Document ID
Document Type
Reprint (Version printed in journal)
Reddy, C. A. (NASA Goddard Space Flight Center Greenbelt, Maryland, United States)
Ravindran, Sudha (Vikram Sarabhai Space Centre Trivandrum, India)
Viswanathan, K. S. (Vikram Sarabhai Space Centre Trivandrum, India)
Murthy, B. V. Krishna (Vikram Sarabhai Space Centre Trivandrum, India)
Rao, D. R. K. (Indian Institute of Geomagnetism Colaba, Bombay, India)
Araki, T. (Kyoto University Kyoto, Japan)
Date Acquired
August 16, 2013
Publication Date
July 1, 1994
Publication Information
Publication: Annales Geophysicae
Volume: 12
Issue: 6
ISSN: 0992-7689
Subject Category
Distribution Limits