Hostname: page-component-78c5997874-j824f Total loading time: 0 Render date: 2024-11-03T08:53:53.824Z Has data issue: false hasContentIssue false
  • English
  • Français

Discrete polar cap aurora observed from Spitsbergen

Published online by Cambridge University Press:  27 October 2009

D.A.R. Simmons  and
K. Henriksen
D.A.R. Simmons
Affiliation:
21 Dougalston Avenue, Milngavie, Scotland
K. Henriksen
Affiliation:
The Auroral Observatory, University of Tromsφ, N-9001 Tromsφ, Norway
Get access Rights & Permissions [Opens in a new window]

Abstract

Discrete auroral arcs frequently bridge the polar cap connecting the morning and evening sectors of the auroral oval along the line of the transpolar (electron) current. Very high-latitude stations that lie wholly within the oval during the earth's diurnal rotation pass under this bridge twice a day, giving morning and evening maxima. Stations at slightly lower latitudes on Spitsbergen lie within the oval in the evening but under, or even south of, the oval in the morning. From such stations the evening, but not the morning, maximum is readily observed. This study is primarily concerned with the orientation of discrete polar cap arcs in the evening skies over Spitsbergen. It shows that the geomagnetic alignment of these arcs is latitude-dependent between geomagnetic colatitudes 6 to 20°N. At the highest latitudes within this range, the arcs are in transpolar alignment, whereas at the lowest latitudes within the polar cap, they are oval-aligned. At intermediate latitudes, the arcs are observed in transitional phases between transpolar and ovalalignment. The solar alignment of discrete polar cap arcs is a function of corrected geomagnetic local time. In the early afternoon, solar alignment is poor but this gradually improves throughout the late afternoon until there is excellent alignment at the time of the evening maximum. Recent satellite studies of plasma convection in the polar ionosphere have helped to explain some of the visual characteristics of discrete polar cap aurora observed from Spitsbergen, particularly the irregular alignment of arcs in the region of the Harang discontinuity.

Type
Articles
Information
Polar Record , Volume 28 , Issue 166 , July 1992 , pp. 191 - 204
Copyright
Copyright © Cambridge University Press 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Akasofu, S-I. 1964. The development of the auroral substorm. Planetary Space Science 12: 273–82.CrossRefGoogle Scholar
Akasofu, S-I., Chapman, S., and Meng, C.I. 1965. The polarelectrojet. Journal of Atmospheric and Terrestrial Physics 27: 1275–305.CrossRefGoogle Scholar
Burke, W.J., Kelley, M.C., Sagalyn, R.C., Smiddy, M., and Lai, S.T. 1979. Polar cap electric field structures with a northward interplanetary magnetic field. Geophysical Research Letters 6: 21–24.CrossRefGoogle Scholar
Crooker, N.U. 1979. Dayside merging and cusp geometry. Journal of Geophysical Research 84: 951–59.CrossRefGoogle Scholar
Davis, T.N. 1962. The morphology of the auroral displays of 1957–1958.2. Detailed analyses of Alaska data and analyses of high-latitude data. Journal of Geophysical Research 67: 75–110.CrossRefGoogle Scholar
Eather, R.H., and Akasofu, S-I. 1969. Characteristics of polar cap auroras. Journal of Geophysical Research 74: 4794–98.CrossRefGoogle Scholar
Feldstein, Y.I., and Starkov, G.V. 1967. Dynamics of auroral belt and polar geomagnetic disturbances. Planetary Space Science 15: 209–29.CrossRefGoogle Scholar
Feldstein, Y.I., and Starkov, G.V. 1968. Auroral oval in the IGY and IGSY period and a ring current in the magnetosphere. Planetary Space Science 16: 129–33.CrossRefGoogle Scholar
Frank, L.A., and 13 others. 1986. The theta aurora. Journal of Geophysical Research 91: 3177–224.CrossRefGoogle Scholar
Franklin, J. 1975. Narrative of a journey to the shores of the Polar Sea in the years 1819,20,21, and22. Edmonton, M.G. Hurtig. (First published 1823, London, John Murray.)Google Scholar
Fritz, H. 1881. Das Polarlicht. Leipzig, Brockhaus.Google Scholar
Gussenhoven, M.S. 1982. Extremely high-latitude auroras. Journal of Geophysical Research 87: 2401–412.CrossRefGoogle Scholar
Gustafsson, G. 1967. On the orientation of auroral arcs. Planetary Space Science 15: 277–94.CrossRefGoogle Scholar
Hakura, Y. 1965. Tables and maps of geomagnetic coordinates corrected by the higher order spherical harmonic terms. Report of Ionosphere and Space Research in Japan 19: 121–57.Google Scholar
Hultqvist, B. 1958. The geomagnetic field lines in higher approximation. Arkiv. für Geofysik 3: 63–77.Google Scholar
Ismail, S., Wallis, D.D., and Cogger, L.L. 1977. Characteristics of polar cap sun-aligned arcs. Journal of Geophysical Research 82: 4741–49.CrossRefGoogle Scholar
Jones, A.V. 1974. Aurora. Geophysics and Astrophysics Monographs. Dordrecht., D. Reidel Publishing Co.Google Scholar
Lassen, K. 1969. Polar cap emissions. In: McCormack, B.M., and Omholt, A. (editors). Aurora and airglow: proceedings of the NATO Advanced Study Institute, July 28–August 9, 1968. New York, Van Nostrand-Reinhold.Google Scholar
Loomis, E. 1860. On the geographical distribution of auroras in the northern hemisphere. American Journal of Science and Arts. 2nd. series. 30: 79–100.CrossRefGoogle Scholar
Mawson, D. 1925. Australasian Antarctic Expedition 1911–1914. Science Reports. Series B. vol. I, part I. Sydney, Government Printing Office.Google Scholar
Meng, C.I., and Akasofu, S-I. 1976. The relation between the polar cap auroral arc and the auroral oval arc. Journal of Geophysical Research 81: 4004–06.CrossRefGoogle Scholar
Montbriand, L.E. 1970. A simple method of calculating the local time of corrected geomagnetic midnight. Journal of Geophysical Research 75: 5634–36.CrossRefGoogle Scholar
National Oceanic and Atmospheric Administration. 1988. Solar-geophysical data. Part 1. Prompt reports. Boulder, Colorado, National Oceanic and Atmospheric Administration, National Geophysical Data Centre, no.524: 103.Google Scholar
Neilson, E., Craven, J.D., Frank, L.A., and Heelis, R.A. 1990. Ionospheric flows associated with a transpolar arc. Journal of Geophysical Research 95: 21, 169–78.Google Scholar
Nishida, A. 1968. Geomagnetic DP2 fluctuations and associated magnetospheric phenomena. Journal of Geophysical Research 73: 1795–803.CrossRefGoogle Scholar
Pellinen, R.J., Koskinen, H.E.J., Pulkkinen, T.I., Murphree, J.S., Rostoker, G., and Opgenoorth, H.J. 1990. Satellite and ground-based observations of a fading transpolar arc. Journal of Geophysical Research 95: 5817–24.CrossRefGoogle Scholar
Rees, M.H. 1963. Auroral lonization and excitation by incident energetic electrons. Planetary Space Science 11: 1209–18.CrossRefGoogle Scholar
Simmons, D.A.R., and Henriksen, H. 1988. Polar cap and other auroral events observed from Spitsbergen. Polar Record 24: 87–94.CrossRefGoogle Scholar
Simmons, D.A.R., Henriksen, K., Taylor, M., and Hermansen, D. 1990. A remarkable outburst of solar activity and its geomagnetic effects. Journal of the British Astronomical Association 100: 280–86.Google Scholar
Smart, W.M. 1971. Spherical astronomy. Cambridge, Cambridge University Press.Google Scholar
Starkov, G.V. 1968. Auroral heights in the polar cap. Geomagnetism and Aeronomy 7: 28.Google Scholar