Equatorial enhancement of Pc5–6 magnetic storm time geomagnetic pulsations
Earth, Planets and Space volume 51, pages 959–964 (1999)
Geomagnetic Pc5–6 (1–4 mHz) pulsations during three magnetic storms have been analyzed using ground observations at an array of 5 Indian stations ranging from 0.8° to 25° dip latitudes and two pairs of low-latitudes (~20°)—near equator (~4–5°) stations, located at ~4 hours to the West and East from this meridian. The pulsations are found to occur as individual wave packets that are characterized by similar spectra at all stations with two dominate bands of frequencies: ~1.5–2.0 mHz and ~2.5–4.0 mHz. Very strong daytime equatorial enhancement of the wave intensity has been noted. The higher enhancement is observed near noon while it is reduced towards the morning and evening sectors. The polarization of both frequency bands at the equator is found to be almost linear, mainly along the H-direction. It has been found that the amplitude of the D-component decreased with decrease in the latitude towards the equator. One of the spectral peaks is observed exclusively at the dip equator station and it has been attributed to the generation/amplification of MHD waves by the equatorial electrojet instabilities. The mechanism of day time equatorial enhancement of long period geomagnetic pulsations and the propagation characteristics are discussed.
Bolshakova, O. V., O. K. Borovkova, Ya. F. Borovkov, N. G. Kleimenova, and J. Bitterly, Magnetic storm on 13 March 1989: The structure of extremely disturbed magnetosphere obtained from geomagnetic pulsations Pc5, Geomagn. Aeron., 34, 492–500, 1995 (English translation).
Dunlop, I. S., F. W. Menk, H. J. Hansen, B. J. Fraser, and R. J. Morris, A multistation study of long period geomagnetic pulsations at cusp and boundary layers latitudes, J. Atmos. Terr. Phys., 56, 667–679, 1994.
Federov, E., V. Pilipenko, V. Surkov, D. R. K. Rao, and K. Yumoto, Ionospheric propagation of magnetohydrodynamic disturbances from the equatorial inosphere, J. Geophys. Res., 104, 4329–4336, 1999.
Green, C. A., The longitudinal phase variation of mid-latitude Pc3–4 micropulsations, Planet. Space Sci., 24, 79–85, 1976.
Harrold, B.G. and J. C. Samson, Standing ULF modes of the magnetosphere: a theory, Geophys. Res. Lett., 19, 1811–1814, 1992.
Herron, T. J., Phase characteristics of geomagnetic micropulsations, J. Geophys. Res., 71, 871–889, 1966.
Jain, A. R. and K. G. A. Srinivasacharya, Study of magnetic pulsations in the Indian equatorial region, J. Atmos. Terr. Phys., 37, 1477–1483, 1975.
Kikuchi, T., Evidence of transmission of the polar electric fields to the low latitude at time of geomagnetic sudden commencements, J. Geophys. Res., 91, 3101–3105, 1986.
Kikuchi, T. and T. Araki, Horizontal transmission of the polar electric field to the equator, J. Atmos. Terr. Phys., 41, 927–936, 1979.
Kitamura, T. I., O. Saka, M. Shimoizzumi, H. Tachihara, T. Oguti, T. Araki, N. Sato, M. Ishitsuka, O. Veliz, and J. B. Nyobe, Global mode of Pi2 waves in the equatorial regions—difference of Pi2 mode between high and equatorial latitudes, J. Geomag. Geoelectr., 40, 621–634, 1988.
Lilley, F. E. M. and D. J. Bennett, Micropulsations recorded by an array of magnetic variometers, J. Geophys. Res., 78, 1603–1607, 1973.
Liu, J. Y., Y. N. Huang, and F. T. Berkey, The phase relationship between ULF geomagnetic pulsations and HF Doppler frequency shift oscillations on March 24, 1991, J. Geomag. Geoelectr., 45, 109–114, 1993.
McHarg, M. G., J. V. Olson, and P. T. Newell, ULF cusp pulsations: diurnal variations and interplanetary magnetic field correlations with ground-based observations, J. Geophys. Res., 100, 19729–19742, 1995.
Olson, J. V. and G. Rostoker, Longitudinal phase variations of PC4–5 micropulsations, J. Geophys. Res., 83, 2481–2488, 1978.
Otnes, R. K. and L. Enochson, Applied Time Series Analysis, V.1 Basic Techniques, 449 pp., Wiley-Interscience, New York, 1978.
Rao, D. R. K., A result on Pc3–4 waves in the Indian equatorial region, J. Geomag. Geoelectr., 48, 1443–1449, 1996.
Reddy, C. A., S. Ravindran, K. S. Viswanathan, B. V. Krishna Murthy, D. R. K. Rao, and T. Araki, Observations of Pc5 micropulsation-related electric field oscillations in the equatorial ionosphere, Ann. Geophys., 12, 565–573, 1994.
Roy, M., D. R. K. Rao, B. M. Pathan, and R. L. Asinkar, Quiet time PS6 pulsation associated with equatorial electrojet irregularities, J. Atmos. Sol.-Terr. Phys., 1999 (in press).
Ruohoniemi, J. M., R. A. Greenwald, K. B. Baker, and J. C. Samson, HF radar observations of Pc5 field line resonances in the midnight/early morning MLT sector, J. Geophys. Res., 96, 15697–15710, 1991.
Saito, T., Resonance model on Pc3 sub-tropic region, in Contribuciones Cientificas para Conmemorar el 75 Aniversario del Observatorio del Ebro, pp. 175–180, 1983.
Saka, O., T. I. Kitamura, M. Shimoizzumi, T. Araki, T. Oguti, O. Veliz, and M. Ishitsuka, The effects of Non-Uniform Ionosphere on the Equatorial PC Pulsations, J. Geomag. Geoelectr., 40, 635–643, 1988.
Samson, J. C., B. G. Harrold, J. M. Ruohoniemi, R. A. Greenwald, and A. D. M. Walker, Field line resonances associated with MHD waveguides in the magnetosphere, Geophys. Res. Lett., 19, 441–444, 1992.
Sarma, S. V. S. and T. S. Sastry, On the equatorial electrojet influence on geomagnetic pulsation amplitudes, J. Atmos. Terr. Phys., 57, 749–754, 1995.
Sarma, S. V. S., T. S. Sastry, and Y. S. Sarma, On the latitudinal variation of magneto-telluric source field in the equatorial region of India, J. Geomag. Geoelectr., 43, 677–684, 1991.
Sastry, T. S., Y. S. Sarma, and S. V. S. Sarma, Equatorial electrojet effects on geomagnetic pulsations, Ind. J. Radio Space Phys., 8, 249–253, 1979.
Sastry, T. S., Y. S. Sarma, and S. V. S. Sarma, Daytime Pi-pulsations in the equatorial region of India, J. Atmos. Terr. Phys., 45, 733–741, 1983.
Schott, J. J., N. G. Kleimenova, J. Bitterly, and O. V. Kozyreva, The strong Pc5 geomagnetic pulsations in the initial phase of the great magnetic storm of March 24, 1991, Earth Planets Space, 50, 101–106, 1998.
Shinohara, M., K. Yumoto, N. Hosen, A. Yoshikawa, H. Tachihara, O. Saka, T. I. Kitamura, N. B. Trivedi, J. M. Da Costa, and N. J. Schuch, Wave characteristics of geomagnetic pulsations across the dip equator, J. Geophys. Res., 103, 11745–11754, 1998.
Sorokin, V. and G. V. Fedorovich, Propagation of short period waves in the ionosphere, Izv. VUZov (Radiofizika), 25, 495–507, 1982.
Trivedi, N. B., B. R. Arora, A. L. Padilha, J. M. Da Costa, S. L. Dutra, F. H. Chamalaun, and A. Rigoti, Global Pc5 geomagnetic pulsations of March 24, 1991, as observed along the American sector, Geophys. Res. Lett., 24, 1683–1686, 1997.
Walker, A. D. M., J. M. Ruohononiemi, K. B. Baker, R. A. Greenwald, and J. C. Samson, Spatial and temporal behavior of ULF pulsations observed by Goose bay HF radar, J. Geophys. Res., 97, 12187–12202, 1992.
Ziesolleck, C. W. S. and F. H. A. Chamalaun, A two dimensional array study of low-latitude Pc5 geomagnetic pulsations, J. Geophys. Res., 98, 13705–13713, 1993.
Ziesolleck, C. W. S. and D. R. McDiarmid, Auroral latitude Pc5 field line resonances: Quantized frequencies, spatial characteristics and diurnal variation, J. Geophys. Res., 99, 5817–5830, 1994.
About this article
Cite this article
Pathan, B.M., Kleimenova, N.G., Kozyreva, O.V. et al. Equatorial enhancement of Pc5–6 magnetic storm time geomagnetic pulsations. Earth Planet Sp 51, 959–964 (1999). https://doi.org/10.1186/BF03351566
- Magnetic Storm
- Geomagnetic Pulsation
- Equatorial Electrojet
- Local Noon
- Equatorial Ionosphere