Observations of Pc5 micropulsation-related electric field oscillations in the equatorial ionosphere

• Main Authors: Reddy, C. A., Ravindran, Sudha, Viswanathan, K. S., Murthy, B. V. Krishna, Rao, D. R. K., Araki, T.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Copernicus Group 1994
• Subjects: QC Physics; Greenland; Narsarsuaq
• Online Access: http://repository.ias.ac.in/68477/; http://www.springerlink.com/content/p7726520n2330217/

A 54.95-MHz coherent backscatter radar, an ionosonde and the magnetometer located at Trivandrum in India (8.5°N, 77°E, 0.5°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 p =161). Simultaneous 100-nT-level fluctuations are also observed in the H-component at Brorfelde, Denmark (55.6°N gm) and at Narsarsuaq, Greenland (70.6°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 −1 and it increases with height, while it is about 1.0 mV m −1 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 Brorfelde are in phase with each other. The observations are interpreted in terms of a compressional cavity mode resonance in the inner magnetosphere and the associated ionospheric electric field penetrating from high latitudes to the magnetic equator.