Electric fields and currents at the Harang discontinuity: a case study
Article Sidebar
Published:
Feb 27, 1986
Keywords:
Polar ionosphere,
Harang discontinuity,
Ionospheric electric field,
Ionospheric conductivity,
Ionospheric and field-aligned currents
Volumes
Vols. 1-18 (1924-1944), ISSN 0044-2801
Main Article Content
Abstract
On 2 December 1977, 1600-1700 UT (around 19 MLT) a section of the Harang discontinuity moved westward over northern Scandinavia with a velocity of about 1 km/s, during a disturbed time interval. The westward movement was clearly identified in the IMS Scandinavian Magnetometer Array observations and is consistent with simultaneous ST ARE electric field measurements. The magnetic measurements showed a marked increase of the overhead current density during the westward movement while the electric field amplitudes stayed at the same level, thus indicating a temporal enhancement of the ionospheric conductivity. The westward movement gave the opportunity to combine subsequently observed two-dimensional distributions of equivalent current vectors (after correction for the magnetic field intensity increase) and electric field vectors into two corresponding patterns fairly extended in the east-west direction and covering the total extent of the most interesting part of the Harang discontinuity region. The electrically defined Harang discontinuity was located 200-300 km to the north of the magnetically defined discontinuity. The combined observational data were used to determine, as far as possible, the ionospheric distributions of height-integrated conductivities, of horizontal height-integrated current density vectors and of field-aligned currents. The results show a reduction of the Hall conductivities and upward Birkeland currents at and around the electrically defined Harang discontinuity. Some horizontal ionospheric current crosses the discontinuity, being diverged northward from the eastward electrojet and joining the westward electrojet, after further counterclockwise rotation.
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Article Details
How to Cite
Kunkel, T., Untiedt, J., Baumjohann, W., & Greenwald, R. (1986). Electric fields and currents at the Harang discontinuity: a case study. Journal of Geophysics, 59(1), 73-86. Retrieved from https://journal.geophysicsjournal.com/JofG/article/view/219
Section
References
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drifting omega bands. J. Geophys. 50:194-201
Banks, P.M., Doupnik, J.R. (1975) A review of auroral zone electrodynamics deduced from incoherent scatter radar observations. J. Atmos. Terr. Phys. 37:951-972
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. (1983) Ionospheric and field-aligned current systems in the auroral zone: A concise review. Adv. Space Res. 2, No. 10:55-62
Baumjohann, W., Greenwald, R.A., Kiippers, F. (1978) Joint magnetometer array and radar backscatter observations of auroral currents in northern Scandinavia. J. Geophys. 44:373-383
Baumjohann, W., Untiedt, J., Greenwald, R.A. (1980) Joint two-dimensional observations of ground magnetic and ionospheric electric fields associated with auroral zone currents. 1. Three-dimensional
current flows associated with a substorm-intensified eastward electrojet. J. Geophys. Res. 85:1963-1978
Baumjohann, W., Pellinen, R.J., Opgenoorth, H.J., Nielsen, E. (1981) Joint two-dimensional observations of ground magnetic and ionospheric electric fields associated with auroral zone currents: Current systems associated with local auroral break-ups. Planet. Space Sci. 29:431-447
Burrage, M.D., Waldock, J.A., Jones, T.B., Nielsen, E. (1985) Joint STARE and SABRE radar auroral observations of the highlatitude ionospheric convection pattern. Nature 316:133-135
Cahill, Jr., L.J., Greenwald, R.A., Nielsen, E. (1978) Auroral radar and rocket double-probe observations of the electric field across the Harang discontinuity. Geophys. Res. Lett. 5:687-690
Ecklund, W.L., Balsley, B.B., Carter, D.A. (1977) A preliminary comparison of F region plasma drifts and E region irregularity drifts in the auroral zone. J. Geophys. Res. 82:195-197
Greenwald, R.A. (1974) Diffuse radar aurora and the gradient drift instability. J. Geophys. Res. 79:4807-4810
Greenwald, R.A. (1979) Studies of currents and electric fields in the auroral zone ionosphere using radar auroral backscatter. In: Akasofu, S.-I. (Ed.) Dynamics of the magnetosphere, pp 213-248. Dordrecht: D. Reidel
Greenwald, R.A., Weiss, W., Nielsen, E., Thomson, N.R. (1978) STARE: A new radar auroral backscatter experiment in northern Scandinavia. Radio Sci. 13:1021-1039
Gustafsson, G. (1970) A revised corrected geomagnetic coordinate system. Ark. Geofys. 5:595-617
Gustafsson, G., Baumjohann, W., Iversen, I. (1981) Multi-method observations and modelling of the three-dimensional currents associated with a very strong Ps6 event. J. Geophys. 49:138-145
Harang, L. (1946) The mean field of disturbance of polar geomagnetic storms. Terr. Mag. Atmos. Electr. 51:353-380
Heppner, J.P. (1967) High latitude magnetic disturbances (A brief review with initial results from motion picture presentation). In: Mc Corrnac, B.M. (Ed.) Aurora and airglow, pp 75-92. Reinhold, New York
Heppner, J.P. (1972) The Harang discontinuity in auroral belt ionospheric currents. Geofys. Publ. 29:105-120
Heppner, J.P. (1977) Empirical models of high-latitude electric fields. J. Geophys. Res. 82:1115-1125
Horwitz, J.L., Doupnik, J.R., Banks, P.M. (1978a) Chatanika radar observations of the latitudinal distributions of auroral zone electric fields, conductivities, and currents. J. Geophys. Res. 83:1463-1481
Horwitz, J.L., Doupnik, J.R., Banks, P.M., Kamide, Y., Akasofu, S.-I. (1978b) The latitudinal distributions of auroral zone electric fields and ground magnetic perturbations and their response to variations in the interplanetary magnetic field. J. Geophys. Res. 83:2071-2084
Hughes, T.J., Rostoker, G. (1979) A comprehensive model current system for high-latitude magnetic activity - I. The steady state system. Geophys. J. R. Astron. Soc. 58:525-569
Iijima, T., Potemra, T.A. (1978) Large-scale characteristics of fieldaligned currents associated with substorms. J. Geophys. Res. 83:599-615
Inhester, B., Baumjohann, W., Greenwald, R.A., Nielsen, E. (1981) Joint two-dimensional observations of ground magnetic and ionospheric electric fields associated with auroral zone currents. 3. Auroral zone currents during the passage of a westward travelling surge. J. Geophys. 49:155-162
Jones, A.G. (1983) The electrical structure of the lithosphere and asthenosphere beneath the Fennoscandian shield. J. Geomagn. Geoelectr. 35:811-827
Kamide, Y. (1978) On current continuity at the Harang discontinuity. Planet. Space Sci. 26:237-244
Kamide, Y. (1982) The relationship between field-aligned currents and the auroral electrojets: A review. Space Sci. Rev. 31:127-243
Kamide, Y., Akasofu, S.-I., Brekke, A. (1976a) Ionospheric currents obtained from the Chatanika radar and ground magnetic perturbations at the auroral latitude. Planet. Space Sci. 24:193-201
Kamide, Y., Vickrey, J.F. (1983) Variability of the Harang discontinuity as observed by the Chatanika radar and the IMS Alaska magnetometer chain. Geophys. Res. Lett. 10:159-162
Kamide, Y., Yasuhara, F., Akasofu, S.-I. (1976b) A model current system for the magnetospheric substorrn. Planet. Space Sci. 24:215-222
Kuppers, F., Untiedt, J., Baumjohann, W., Lange, K., Jones, A.G. (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
Maurer, H., Theile, B. (1978) Parameters of the auroral electrojet from magnetic variations along a meridian. J. Geophys. 44:415-426
Maynard, N .C. (1974) Electric field measurements across the Harang discontinuity. J. Geophys. Res. 79:4620-4631
Murison, M., Richmond, A.D., Matsushita, S. (1985) Estimation of ionospheric electric fields and currents from a regional magnetometer array. J. Geophys. Res. 90:3525-3530
Nielsen, E., Greenwald, R.A. (1979) Electron flow and visual aurora at the Harang discontinuity. J. Geophys. Res. 84:4189-4200
Nielsen, E., Schlegel, K. (1983) A first comparison of ST ARE and EISCAT electron drift velocity measurements. J. Geophys. Res. 88:5745-5750
Nielsen, E., Schlegel, K. (1985) Coherent radar Doppler measurements and their relationship to the ionospheric electron drift velocity. J. Geophys. Res. 90:3498-3504
Opgenoorth, H.J., Oksman, J., Kaila, K.U., Nielsen, E., Baumjohann, W. (1983a) Characteristics of eastward drifting omega bands in the morning sector of the auroral oval. J. Geophys. Res. 88:9171-9185
Opgenoorth, H.J., Pellinen, R.J., Baumjohann, W., Nielsen, E., Marklund, G., Eliasson, L. (1983b) Three-dimensional current flow and particle precipitation in a westward travelling surge (observed during the Barium - GEOS rocket experiment). J. Geophys. Res. 88:3138-3152
Richmond, A.D., Baumjohann, W. (1983) Three-dimensional analysis of magnetometer array data. J. Geophys. 54:138-156
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
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. Geophys. Res. 80:3571-3579
Vickrey, J.F., Vondrak, R.R., Matthews, S.J. (1981) The diurnal and latitudinal variation of auroral zone ionospheric conductivity. J. Geophys. Res. 86:65-75
Waldock, J.A., Jones, T.B., Nielsen, E. (1985) Mean auroral E-region plasma convection patterns measured by SABRE. Nature 313:204-206
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
Wiens, R.G., Rostoker, G. (1975) Characteristics of the development of the westward electrojet during the expansive phase ofmagnetospheric substorms. J. Geophys. Res. 80:2109-2128
Zanetti, Jr., L.J., Arnoldy, R.L., Cahill, Jr., L.J., Behm, D.A., Greenwald, R.A. (1980) Comparative rocket observations of ionospheric electric fields in the auroral oval. Space Sci. Instr. 5:183-196
Zi, M., Nielsen, E. (1982) Spatial variation of electric fields in the highlatitude ionosphere. J. Geophys. Res. 87:5202-5206
Ziesolleck, Ch., Baumjohann, W., Bruning, K., Carlson, C.W., Bush, R.I. (1983) Comparison of height-integrated current densities derived from ground-based magnetometer and rocket-borne observations during the Porcupine F 3 and F 4 flights. J. Geophys. Res. 88:8063-8072
drifting omega bands. J. Geophys. 50:194-201
Banks, P.M., Doupnik, J.R. (1975) A review of auroral zone electrodynamics deduced from incoherent scatter radar observations. J. Atmos. Terr. Phys. 37:951-972
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. (1983) Ionospheric and field-aligned current systems in the auroral zone: A concise review. Adv. Space Res. 2, No. 10:55-62
Baumjohann, W., Greenwald, R.A., Kiippers, F. (1978) Joint magnetometer array and radar backscatter observations of auroral currents in northern Scandinavia. J. Geophys. 44:373-383
Baumjohann, W., Untiedt, J., Greenwald, R.A. (1980) Joint two-dimensional observations of ground magnetic and ionospheric electric fields associated with auroral zone currents. 1. Three-dimensional
current flows associated with a substorm-intensified eastward electrojet. J. Geophys. Res. 85:1963-1978
Baumjohann, W., Pellinen, R.J., Opgenoorth, H.J., Nielsen, E. (1981) Joint two-dimensional observations of ground magnetic and ionospheric electric fields associated with auroral zone currents: Current systems associated with local auroral break-ups. Planet. Space Sci. 29:431-447
Burrage, M.D., Waldock, J.A., Jones, T.B., Nielsen, E. (1985) Joint STARE and SABRE radar auroral observations of the highlatitude ionospheric convection pattern. Nature 316:133-135
Cahill, Jr., L.J., Greenwald, R.A., Nielsen, E. (1978) Auroral radar and rocket double-probe observations of the electric field across the Harang discontinuity. Geophys. Res. Lett. 5:687-690
Ecklund, W.L., Balsley, B.B., Carter, D.A. (1977) A preliminary comparison of F region plasma drifts and E region irregularity drifts in the auroral zone. J. Geophys. Res. 82:195-197
Greenwald, R.A. (1974) Diffuse radar aurora and the gradient drift instability. J. Geophys. Res. 79:4807-4810
Greenwald, R.A. (1979) Studies of currents and electric fields in the auroral zone ionosphere using radar auroral backscatter. In: Akasofu, S.-I. (Ed.) Dynamics of the magnetosphere, pp 213-248. Dordrecht: D. Reidel
Greenwald, R.A., Weiss, W., Nielsen, E., Thomson, N.R. (1978) STARE: A new radar auroral backscatter experiment in northern Scandinavia. Radio Sci. 13:1021-1039
Gustafsson, G. (1970) A revised corrected geomagnetic coordinate system. Ark. Geofys. 5:595-617
Gustafsson, G., Baumjohann, W., Iversen, I. (1981) Multi-method observations and modelling of the three-dimensional currents associated with a very strong Ps6 event. J. Geophys. 49:138-145
Harang, L. (1946) The mean field of disturbance of polar geomagnetic storms. Terr. Mag. Atmos. Electr. 51:353-380
Heppner, J.P. (1967) High latitude magnetic disturbances (A brief review with initial results from motion picture presentation). In: Mc Corrnac, B.M. (Ed.) Aurora and airglow, pp 75-92. Reinhold, New York
Heppner, J.P. (1972) The Harang discontinuity in auroral belt ionospheric currents. Geofys. Publ. 29:105-120
Heppner, J.P. (1977) Empirical models of high-latitude electric fields. J. Geophys. Res. 82:1115-1125
Horwitz, J.L., Doupnik, J.R., Banks, P.M. (1978a) Chatanika radar observations of the latitudinal distributions of auroral zone electric fields, conductivities, and currents. J. Geophys. Res. 83:1463-1481
Horwitz, J.L., Doupnik, J.R., Banks, P.M., Kamide, Y., Akasofu, S.-I. (1978b) The latitudinal distributions of auroral zone electric fields and ground magnetic perturbations and their response to variations in the interplanetary magnetic field. J. Geophys. Res. 83:2071-2084
Hughes, T.J., Rostoker, G. (1979) A comprehensive model current system for high-latitude magnetic activity - I. The steady state system. Geophys. J. R. Astron. Soc. 58:525-569
Iijima, T., Potemra, T.A. (1978) Large-scale characteristics of fieldaligned currents associated with substorms. J. Geophys. Res. 83:599-615
Inhester, B., Baumjohann, W., Greenwald, R.A., Nielsen, E. (1981) Joint two-dimensional observations of ground magnetic and ionospheric electric fields associated with auroral zone currents. 3. Auroral zone currents during the passage of a westward travelling surge. J. Geophys. 49:155-162
Jones, A.G. (1983) The electrical structure of the lithosphere and asthenosphere beneath the Fennoscandian shield. J. Geomagn. Geoelectr. 35:811-827
Kamide, Y. (1978) On current continuity at the Harang discontinuity. Planet. Space Sci. 26:237-244
Kamide, Y. (1982) The relationship between field-aligned currents and the auroral electrojets: A review. Space Sci. Rev. 31:127-243
Kamide, Y., Akasofu, S.-I., Brekke, A. (1976a) Ionospheric currents obtained from the Chatanika radar and ground magnetic perturbations at the auroral latitude. Planet. Space Sci. 24:193-201
Kamide, Y., Vickrey, J.F. (1983) Variability of the Harang discontinuity as observed by the Chatanika radar and the IMS Alaska magnetometer chain. Geophys. Res. Lett. 10:159-162
Kamide, Y., Yasuhara, F., Akasofu, S.-I. (1976b) A model current system for the magnetospheric substorrn. Planet. Space Sci. 24:215-222
Kuppers, F., Untiedt, J., Baumjohann, W., Lange, K., Jones, A.G. (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
Maurer, H., Theile, B. (1978) Parameters of the auroral electrojet from magnetic variations along a meridian. J. Geophys. 44:415-426
Maynard, N .C. (1974) Electric field measurements across the Harang discontinuity. J. Geophys. Res. 79:4620-4631
Murison, M., Richmond, A.D., Matsushita, S. (1985) Estimation of ionospheric electric fields and currents from a regional magnetometer array. J. Geophys. Res. 90:3525-3530
Nielsen, E., Greenwald, R.A. (1979) Electron flow and visual aurora at the Harang discontinuity. J. Geophys. Res. 84:4189-4200
Nielsen, E., Schlegel, K. (1983) A first comparison of ST ARE and EISCAT electron drift velocity measurements. J. Geophys. Res. 88:5745-5750
Nielsen, E., Schlegel, K. (1985) Coherent radar Doppler measurements and their relationship to the ionospheric electron drift velocity. J. Geophys. Res. 90:3498-3504
Opgenoorth, H.J., Oksman, J., Kaila, K.U., Nielsen, E., Baumjohann, W. (1983a) Characteristics of eastward drifting omega bands in the morning sector of the auroral oval. J. Geophys. Res. 88:9171-9185
Opgenoorth, H.J., Pellinen, R.J., Baumjohann, W., Nielsen, E., Marklund, G., Eliasson, L. (1983b) Three-dimensional current flow and particle precipitation in a westward travelling surge (observed during the Barium - GEOS rocket experiment). J. Geophys. Res. 88:3138-3152
Richmond, A.D., Baumjohann, W. (1983) Three-dimensional analysis of magnetometer array data. J. Geophys. 54:138-156
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
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. Geophys. Res. 80:3571-3579
Vickrey, J.F., Vondrak, R.R., Matthews, S.J. (1981) The diurnal and latitudinal variation of auroral zone ionospheric conductivity. J. Geophys. Res. 86:65-75
Waldock, J.A., Jones, T.B., Nielsen, E. (1985) Mean auroral E-region plasma convection patterns measured by SABRE. Nature 313:204-206
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
Wiens, R.G., Rostoker, G. (1975) Characteristics of the development of the westward electrojet during the expansive phase ofmagnetospheric substorms. J. Geophys. Res. 80:2109-2128
Zanetti, Jr., L.J., Arnoldy, R.L., Cahill, Jr., L.J., Behm, D.A., Greenwald, R.A. (1980) Comparative rocket observations of ionospheric electric fields in the auroral oval. Space Sci. Instr. 5:183-196
Zi, M., Nielsen, E. (1982) Spatial variation of electric fields in the highlatitude ionosphere. J. Geophys. Res. 87:5202-5206
Ziesolleck, Ch., Baumjohann, W., Bruning, K., Carlson, C.W., Bush, R.I. (1983) Comparison of height-integrated current densities derived from ground-based magnetometer and rocket-borne observations during the Porcupine F 3 and F 4 flights. J. Geophys. Res. 88:8063-8072