- Open Access
Frequency dependence of equatorial electrojet effect on geomagnetic micropulsations
Earth, Planets and Space volume 50, pages847–851(1998)
The micropulsation data (Pc3–Pc4 range) from off-equatorial and equatorial stations Alibag (ABG) and Tirunelvelli (TIR) in the Indian zone during 1991 are analysed for delineating the electrojet effect. The ratios of the spectral amplitudes at significant frequency bands the horizontal component of the magnetic field at TIR to that at ABG are worked out as a function of frequency. The results show that the lower frequencies undergo larger equatorial amplification. However, above a certain frequency the pulsation signal is found to attenuate rather than exhibit the general enhancement. The ratio becomes minimum around the period, 18 to 24 sec. At further higher frequencies, there is again the normal electrojet amplification. The explanation of such a behaviour of the electrojet on the pulsation amplitude is rather difficult at the present stage and to some extent becomes controversial even if it is offered.
Green, A. W. and E. W. Worthington, Alfven field line resonance at low latitude (L = 1.5), J. Geophys. Res., 98, 15693–15699, 1993.
Hattingh, S. K. F. and P. R. Sutcliffe, Pc 3 pulsation Eigenperiods determination at low latitudes, J. Geophys. Res., 92, 12433–12436, 1987.
Hughes, W. J. and D. J. Southwood, The screening of micropulsation signals by the atmosphere and the ionosphere, J. Geophys. Res., 81, 3234–3240, 1976.
Matsuoka, H., K. Takahashi, S. Kokubun, K. Yumoto, T. Yamamoto, S. I. Solovyev, and E. F. Vershinin, Phase and amplitude structure of Pc 3 magnetic pulsations as determined from multipoint observations, J. Geophys. Res., 102, 2391–2403, 1997.
Newton, R. S., D. J. Southwood, and W. J. Hughes, Damping of geomagnetic pulsation by the ionosphere, Planet. Space Sci., 26, 201–209, 1978.
Orr, D. and J. A. D. Mathew, The variation of geomagnetic micropulsation periods with latitude, Planet. Space Sci., 19, 897–905, 1971.
Osaki, H., K. Yumoto, K. Fukao, K. Shiokawa, F. W. Menk, B. J. Fraser, and the 210° MM Magnetic Observation Group, Characteristics of low-latitude Pi 2 pulsations along the 210° Magnetic Meridian, J. Geomag. Geoelectr., 48, 1421–1430, 1996.
Poulter, E. M., W. Allan, G. J. Bailey, and R. J. Moffett, On the diurnal period variation of midlatitude ULF pulsations, Planet. Space Sci., 32, 727–734, 1984.
Poulter, E. M., W. Allan, and G. J. Bailey, ULF pulsation eigen periods within the plasmasphere, Planet. Space Sci., 36, 185–196, 1988.
Saito, T., K. Yumoto, M. Seto, S. I. Akasofu, E. J. Smith, and B. T. Tsurutani, Characteristics of Pc 3’s recorded simultaneously by rulfmeters at Circem Northern Pacific station, Proc. 4th IAGA Scientific Assembly, Edinburgh, 1981.
Sarma, S. V. S. and T. S. Sastry, On the equatorial electrojet influence on geomagnetic pulsation amplitude, J. Atmos. Terr. Phys., 57, 749–754, 1995.
Sastry, T. S., Y. S. Sarma, and S. V. S. Sarma, Equatorial electrojet effect on Geomagnetic pulsations, Ind. J. Rad. Space Phys., 8, 249–253, 1979.
Shinohara, M., K. Yumoto, A. Yoshikawa, O. Saka, S. I. Solovyev, E. F. Vershinin, N. B. Trivedi, J. M. Da Costa, and The 210° MM Magnetic Observation Group, Wave characteristics of day time and night time Pi 2 pulsations at the equatorial and low latitudes, Geophys. Res. Lett., 24, 2279–2282, 1997.
Singer, H. J., D. J. Southwood, R. J. Walker, and M. G. Kivelson, Alfven wave resonances in a realistic magnetospheric magnetic field geometry, J. Geophys. Res., 86, 4589–4596, 1981.
Udare, R. S., Geomagnetic pulsations (Pc3-Pc4) recording system: hardware and software, Geol. Soc. India Mem., 24, 241–251, 1992.
Vellante, M., U. Villante, M. De Lauretis, and P. Cerulli-Irelli, An analysis of micropulsation events at a low latitude station during 1985, Planet. Space Sci., 37, 767–773, 1989.
Yumoto, K., V. A. Pilipenko, E. N. Fedorov, N. A. Kurneva, and Yu. G. Habazin, Mechanism of damping of geomagnetic pulsations at low latitude, Geomagn. Aeron., 33, 593–598, 1994 (English Translation).
Yumoto, K., V. A. Pilipenko, E. Fedorov, N. Kurneva, and K. Shiokawa, The mechanism of damping of geomagnetic pulsations, J. Geomag. Geoelectr., 47, 163–176, 1995a.
Yumoto, K. and The 210° MM Magnetic Observation Group, Initial results from the 210° magnetic meridian project-Review, J. Geomag. Geoelectr., 47, 1197–1213, 1995b.
About this article
Cite this article
Roy, M., Rao, D.R.K. Frequency dependence of equatorial electrojet effect on geomagnetic micropulsations. Earth Planet Sp 50, 847–851 (1998). https://doi.org/10.1186/BF03352178
- Pulsation Signal
- Geomagnetic Pulsation
- Indian Zone
- Toroidal Mode
- Hydromagnetic Wave