- Open Access
Conductivity, electric field and electron drift velocity within the equatorial electrojet
Earth, Planets and Space volume 58, pages1071–1077(2006)
Rocket-borne in-situ measurements of electron density and current density made from Thumba, India, on four occasions between 1966 and 1973 and on one flight from Peru in 1965 are studied along with the corresponding ground magnetometer data. The Cowling conductivity is computed using the yearly mean magnetic field values of 1965 and the atmospheric density values from the MSIS 1986 model. The rocket-borne measurements from Thumba cover different geophysical conditions of strong, moderate and partial counter-electrojet events. The vertical profiles of the measured current density and electron density are presented along with the computed Cowling conductivity, electron drift velocity and electric field. The peak current density occurred at 106–107 km over Thumba and at 109 km over Peru compared to 104 km over Brazil. Cowling conductivity peaks occurred at 102 km over Huancayo and 101 km over Thumba, while electron drift velocity and electric field peaks occurred at approximately 105–107 km over Thumba, 108 and 110 km over Huancayo and 104 km over Brazil, respectively. While the electron density near the level of peak current density shows some variability, electron drift velocity and electric field show large variability. We conclude that the local electric field plays an important role in the spatial and temporal variability of the strength of the electrojet.
Baker, N. G. and D. F. Martyn, Electric currents in the ionosphere; The conductivity, Philos. Trans. Roy. Soc. Lond., A246, 281–294, 1953.
Carter, D. A., B. B. Balsley, and W. L. Eckerland, VHF Dopler radar observations of the African Equatorial Electrojet, J. Geophys. Res., 81, 2786–2794, 1976.
Chandra, H., R. K. Misra, and R. G. Rastogi, Equatorial ionospheric drift and electrojet, Planet. Space Sci., 19, 1497–1503, 1971.
Chandra, H., H. S. S. Sinha, and R. G. Rastogi, Equatorial electrojet studies from rocket and ground measurements, Earth Planets Space, 52, 111–120, 2000.
Chapman, S., The equatorial electrojet as detected from the abnormal electric current distributions above Huancayo, Arch. Meteoral. Geophys. Bioclimatal, A4, 368–390, 1951.
Cowling, T. G. and R. Borger, Electrical conductivity in the ionosphere, Nature (Lond), 162, 143, 1948.
Fambitakoye, O., R. G. Rastogi, J. Tabagh, and P. Vila, Counter electrojet and Esq disappearance, J. Atmos. Terr. Phys., 35, 1119–1126, 1973.
Gangepain, J., M. Crochet, and A. D. Richmond, Comparison of equatorial electrojet models, J. Atmos. Terr. Phys., 39, 1119–1124, 1977.
Maynard, N. C., Measurements of ionospheric currents off the coast of Peru, J. Geophys. Res., 72, 1863–1875, 1967.
Pfaff, R. F. Jr., M. H. Acuna, P. A. Marionni, and N. B. Trivedi, DC polarization electric field and current density and plasma density measurements in the daytime eqatorial electrojet, Geophys. Res. Lett, 24, 1667–1670, 1997.
Prakash, S. and B. H. Subbaraya, Langmuir probe for the measurement of electron density and electron temperature in the ionosphere, Rev. Sci. Inst., 38, 1132–1136, 1967.
Rao, T. R. and S. Prakash, Electron plasma resonances detected by a mutual admittance probe in the equatorial ionosphere, Space Res., XVIII, 281–284, 1978.
Rastogi, R. G., Equatorial sporadic-E and plasma instabilities, Nature, 237, 73–75, 1972.
Rastogi, R. G., On the simultaneous existence of eastward and westward flowing equatorial electrojet currents, Proc. Indian Acad. Sci., A81, 80–92, 1975.
Rastogi, R. G., Geomagnetic field variations at low latitudes and ionospheric electric field, J. Atmos. Terr. Phys., 55, 1375–1381, 1993.
Rastogi, R. G. and H. Chandra, Interplanetary magnetic field and the equatorial ionosphere, J. Atmos. Terr. Phys., 36, 377–379, 1974.
Rastogi, R. G. and A. Patil, A complex structure of equatorial electrojet current, Curr. Sci., 85, 433–436, 1986.
Rastogi, R. G., H. Chandra, and S. C. Chakravarty, The disappearance of equatorial Es and the reversal of electrojet current, Proc. Indian Acad. Sci., 74, 62–67, 1971a.
Rastogi, R. G., H. Chandra, and R. K. Misra, Effect of magnetic activity on electron drifts in the equatorial electrojet region, Nature, 233, 13–15, 1971b.
Rastogi, R. G., H. Chandra, and R. K. Misra, Features of the ionospheric drift over the magnetic equator, Space Res., XII, 983–992, 1972.
Richmond, A. D., Equatorial electrojet, I, Development of a model including winds and instabilities, J. Atmos. Terr. Phys., 35, 1083–1103, 1973.
Ronchi, C., R. N. Sudan, and P. L. Similon, Effect of short-scale turbulence on kilometer wavelength irregularities in the equatorial electrojet, J. Geophys. Res., 95, 189–200, 1990.
Sastry, T. S. G., Quiet day electrojet over Thumba, India, J. Geophys. Res., 73, 1789–1794, 1968.
Sastry, T. S. G., Diurnal change in the parameters of the equatorial elec-trojet as observed by rocket-borne magnetometers, Space Res., X, 778–785, 1970.
Sastry, T. S. G., Daily variations of geomagnetic field at the Indian stations under the electrojet during the period of the July 1966 proton flare, J. Geophys. Res., 78, 1692–1698, 1973.
Sinha, H. S. S. and S. Prakash, Electron densities in the equatorial lower ionosphere over Thumba and SHAR, Adv. Space Res., 18, 311–318, 1996.
Sinha, H. S. S., H. Chandra, and R. G. Rastogi, Longitudinal inequalities in the equatorial electrojet, Proc. Nat. Acad. Sci. India, 69(A), 89–96, 1999.
Subbaraya, B. H., S. Prakash, and S. P. Gupta, Electron densities in the equatorial equatorial lower ionosphere from the Langmuir probe experiments conducted at Thumba during the year 966–1978, Scientific report ISRO-PRL-SR-15-83, 1983.
Subbaraya, B. H., P. Muralikrishna, T. S. G. Sastry, and S. Prakash, A study of the structures of electrical conductivities and the electrostatic field within the equatorial electrojet, Planet. Space Sci, 20, 47–52, 1972.
Sugiura, M. and D. J. Poros, An improved model equatorial electrojet with a meridional current system, J. Geophys. Res., 74, 4025–4034, 1969.
Tiwari, D., A. K. Patra, K. S. Viswanathan, N. Jyoti, C. V. Devasia, K. S. V. Subbarao, and R. Sridharan, Simulatenous radar observations of electrojet plasma irregularities at 18 and 54.95 MHz over Trivandrum, India, J. Geophys. Res., 108(A10), 1368, doi:10.1029/2002JA009698, 2003.
Untiedt, J., A model of the equatorial electrojet involving meridional currents, J. Geophys. Res., 72, 5799–5810, 1967.
About this article
Cite this article
Rastogi, R.G., Chandra, H. Conductivity, electric field and electron drift velocity within the equatorial electrojet. Earth Planet Sp 58, 1071–1077 (2006). https://doi.org/10.1186/BF03352612
- Equatorial electrojet
- equatorial ionosphere