Analysis of an eastward electrojet by means of upward continuation of ground-based magnetometer data

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U. Mersmann
W. Baumjohann
F. Kuppers
K. Lange


On October 26, 1975, data from two parallel meridian chains of densely spaced magnetometers in Northern Scandinavia indicated the presence of an evening sector eastward electrojet which between 1606 and 1710 UT was two-dimensional. By separating the relevant components of the magnetic disturbance fields into internal and external parts, and by subsequent upward continuation (towards the source) of the external horizontal component, equivalent height-integrated ionospheric current densities were derived as a function of latitude and time. Whereas the demarcation line between the eastward and westward ionospheric electrojet currents remained stationary, the sharp southern border of the eastward electrojet moved towards the south with a speed of about 50 ms-1 , possibly indicating an earthward movement of the inner edge of the magnetospheric plasma sheet. The maximum eastward height-integrated current density was of the order of 0.5 Am-1 , the corresponding large-scale field-aligned current density has been estimated to have been of the order of 1.0 μAm-2 . After 1630 UT there was evidence for a superposed stationary small-scale structure (wavelength of the order of 250 km) in the eastward flow, which would imply a pair of local field-aligned current sheets possibly related to an auroral arc.

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Mersmann, U., Baumjohann, W., Kuppers, F., & Lange, K. (1978). Analysis of an eastward electrojet by means of upward continuation of ground-based magnetometer data. Journal of Geophysics, 45(1), 281-298. Retrieved from
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Armstrong, J.C., Akasofu, S.-I., Rostoker, G. (1975) A comparison of satellite observations of Birkeland currents with ground observations of visible aurora and ionospheric currents. J. Geophys. Res. 80:575-586

Banks, P.M., Doupnik, J.R., Akasofu, S.-I. (1973) Electric field observations by incoherent scatter radar in the auroral zone. J. Geophys. Res. 78:6607-6622

Baumjohann, W., Greenwald, R.A., Kuppers, F. (1978) Joint magnetometer array and radar backscatter observations of auroral currents in Northern Scandinavia. J. Geophys. 44:373-383

Beaujardiere, O. de la, Vondrak, R., Baron, M. (1977) Radar observations of electric fields and currents associated with auroral arcs. J. Geophys. Res. 82:5051-5062

Bostrom, R. (1964) A model of the auroral electrojets. J. Geophys. Res. 69:4983-5000

Brekke, A., Doupnik, J.R., Banks, P.M. (1974) Incoherent scatter measurements of E-region conductivities and currents in the auroral zone. J. Geophys. Res. 79:3773-3790

Carlson, C.W., Kelley, M.C. (1977) Observation and interpretation of particle and electric field measurements inside and adjacent to an active auroral arc. J. Geophys. Res. 82:2349-2360

Casserly, R.T., Cloutier, P.A. (1975) Rocket-based magnetic observations of auroral Birkeland currents in association with a structured auroral arc. J. Geophys. Res. 80:2165-2168

Czechowsky, P. (1971) Calculation of an equivalent current system in the polar E-region. Radio Sci. 6:247-253

Evans, D.S., Maynard, N.C., Troim, J., Jacobsen, T., Egeland, A. (1977) Auroral electric field and particle comparisons. 2. Electrodynamics of an arc. J. Geophys. Res. 82:2235-2249

Fukushima, N. (1976) Generalized theorem for no ground magnetic effect of vertical currents connected with Pedersen currents in the uniform-conductivity ionosphere. Rep. Ionos. Space Res. Jpn. 30:35-40

Gough, D.I., Reitzel, J.S. (1967) A portable three component magnetic variometer. J. Geomagn. Geoelectr. 19:203-215

Grant, F.S., West, G.F. (1965) Interpretation theory in applied geophysics. McGraw-Hill, New York

Gustafsson, G. (1970) A revised corrected geomagnetic coordinate system. Ark. Geofys. 5:595-617

Horwitz, J.L., Doupnik, J.R., Banks, P.M. (1978) Chatanika radar observations of the latitudinal distributions of auroral zone electric fields, conductivities, and currents. J. Geophys. Res. 83:1463-1481

Iijima, T., Potemra, T.A. (1976) The amplitude distribution of field-aligned currents at northern high latitudes observed by Triad. J. Geophys. Res. 81:2165-2174

Iijima, T., Potemra, T.A. (1978) Large-scale characteristics of field-aligned currents associated with substorms. J. Geophys. Res. 83:599-615

Kamide, Y., Brekke, A. (1975) Auroral electrojet current density deduced from the Chatanika radar and from the Alaska meridian chain of magnetic observatories. J. Geophys. Res. 80:587-594

Kamide, Y., Brekke, A. (1977) Altitude of the eastward and westward auroral electrojets. J. Geophys. Res. 82:2851-2853

Kamide, Y., Fukushima, N. (1972) Positive geomagnetic bays in evening high-latitudes and their possible connection with partial ring current. Rep. Ionos. Space Res. Jpn. 26:79-101

Kamide, Y., Horwitz, J.L. (1978) Chatanika radar observations of ionospheric and field-aligned currents. J. Geophys. Res. 83:1063-1070

Kamide, Y., Rostoker, G. (1977) The spatial relationship of field-aligned currents and auroral electrojets to the distribution of nightside auroras. J. Geophys. Res. 82:5589-5608

Kertz, W. (1954) Modelle fur erdmagnetisch induzierte elektrische Strome im Untergrund. Nachr. Akad. Wiss. Goettingen 1954, Math.-Phys. Kl.:101-110

Kuppers, F., Post, H. (1979) A second generation Gough-Reitzel magnetometer, J. Geomagn. Geoelectr. (accepted for publication)

Kuppers, F., Untiedt, J., Baumjohann, W., Lange, K., Jones, A. (1979) A two-dimensional magnetometer array for ground-based observations of auroral zone electric currents during the International
Magnetospheric Study (IMS). J. Geophys. 46:429-450

Lui, A.T.Y., Venkatesan, D., Anger, C.D., Akasofu, S.-I., Heikkila, W.J., Winningham, J.D., Burrows, J.R. (1977) Simultaneous observations of particle precipitations and auroral emissions by the Isis 2 satellite in the 19-24 MLT sector. J. Geophys. Res. 82:2210-2226

Mallinckrodt, A.J., Carlson, C.W. (1978) Relations between transverse electric fields and the field-aligned currents. J. Geophys. Res. 83:1426-1432

Maynard, N.C. (1974) Electric field measurements across the Harang discontinuity. J. Geophys. Res. 79:4620-4631

Maynard, N.C., Evans, D.S., Maehlum, B., Egeland, A. (1977) Auroral vector electric field and particle comparisons. I. Premidnight convection topology. J. Geophys. Res. 82v2227-2234

McNish, A.G. (1938) Heights of electric currents near the auroral zone. Terr. Magn. Atmos. Electr. 43:67-75

Mende, S.B., Eather, R.H. (1976) Monochromatic all-sky observations and auroral precipitation patterns. J. Geophys. Res. 81:3771-3780

Oldenburg, D.W. (1976) Ionospheric current structure as determined from groundbased magnetometer data. Geophys. J. 46:41-66

Oldenburg, D.W. (1978) A quantitative technique for modelling ionospheric and magnetospheric current distributions. J. Geo phys. Res. 83:3320-3326

Rostoker, G. (1972) Polar magnetic substorms. Rev. Geophys. Space Phys. 10:157-211

Rostoker, G., Armstrong, J.C., Zmuda, A.J. (1975) Field-aligned current flow associated with intrusion of the substorm-intensified westward electrojet into the evening sector. J. Geo phys. Res. 80:3571-3579

Rostoker, G., Kisabeth, J.L. (1973) Response of the polar electrojets in the evening sector to polar magnetic substorms. J. Geophys. Res. 78:5559-5571

Sato, T. (1978) A theory of quiet auroral arcs. J. Geophys. Res. 83:1042-1048

Scrase, F.J. (1967) The electric current associated with polar magnetic sub-storms. J. Atmos. Terr. Phys. 29:567-579

Siebert, M., Kertz, W. (1957) Zur Zerlegung eines lokalen erdmagnetischen Feldes in ausseren und inneren Anteil. Nachr. Akad. Wiss. Gottingen 1957, Math.-Phys. Kl.:87-112

Stauning, P., Christensen, B. (1977) Compilation of Ionlab riometer data for IMS-Workshop in Hankasalmi. Ionlab Rep. R41, Lyngby (Denmark)

Sugiura, M., Potemra, T.A. (1976) Net field-aligned currents observed by Triad. J. Geophys. Res. 81:2155-2164

Untiedt, J., Pellinen, R., Kuppers, F., Opgenoorth, H.J., Pelster, W.D., Baumjohann, W., Ranta, H., Kangas, J., Czechowsky, P., Heikkila, W.J. (1978) Observations of the initial development of an auroral and magnetic substorm at magnetic midnight. J. Geophys. 45:41-65

Wallis, D.D. (1976) Comparison of auroral electrojets and the visible aurora. In: McCormack, B.M. (Ed.) Magnetospheric particles and fields, pp. 247-255. D. Reidel, Dordrecht

Wallis, D.D., Anger, C.D., Rostoker, G. (1976) The spatial relationship of auroral electrojets and visible aurora in the evening sector. J. Geophys. Res. 81:2857-2869

Weaver, J.T. (1964) On the separation of local geomagnetic fields into external and internal parts. J. Geophys. 30:29-36

Wedde, T., Doupnik, J.R., Banks, P.M. (1977) Chatanika observations of the latitudinal structure of electric fields and particle precipitation on November 21, 1975. J. Geophys. Res. 82:2743-2751

Wescott, E.M., Stolarik, J.D., Heppner, J.P. (1969) Electric fields in the vicinity of auroral forms from motions of barium vapor releases. J. Geophys. Res. 74:3469-3487

Winningham, J.D., Yasuhara, F., Akasofu, S.-I., Heikkila, W.J. (1975) The latitudinal morphology of 10-eV to 10-keV electron fluxes during magnetically quiet and disturbed times in the 2100-0300 MLT sector. J. Geophys. Res. 80:3148-3171

Zmuda, A.J., Armstrong, J.C. (1974) The diurnal flow pattern of field-aligned currents. J. Geophys. Res. 79:4611-4619

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