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Asymmetric auroral intensities in the Earth’s Northern and Southern hemispheres


It is commonly assumed that the aurora borealis (Northern Hemisphere) and aurora australis (Southern Hemisphere) are mirror images of each other because the charged particles causing the aurora follow the magnetic field lines connecting the two hemispheres. The particles are believed to be evenly distributed between the two hemispheres, from the source region in the equatorial plane of the magnetosphere. Although it has been shown that similar auroral features in the opposite hemispheres can be displaced tens of degree in longitude1,2 and that seasonal effects can cause differences in global intensity3,4, the overall auroral patterns were still similar. Here we report observations that clearly contradict the common assumption about symmetric aurora: intense spots are seen at dawn in the Northern summer Hemisphere, and at dusk in the Southern winter Hemisphere. The asymmetry is interpreted in terms of inter-hemispheric currents related to seasons, which have been predicted5,6 but hitherto had not been seen.

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Figure 1: Simultaneous ultraviolet images of the aurora in both hemispheres.
Figure 2: Spatio-temporal distribution of auroral intensity in both hemispheres.


  1. Østgaard, N. et al. Observations and model predictions of auroral substorm asymmetries in the conjugate hemispheres. Geophys. Res. Lett. 32 L05111 10.1029/2004GL022166 (2005)

    Article  ADS  Google Scholar 

  2. Østgaard, N., Mende, S. B., Frey, H. U., Sigwarth, J. B., Aasnes, A. & Weygand, J. Auroral conjugacy studies based on global imaging. J. Atmos. Solar-Terr. Phys. (special issue) 69, 249–255 (2007)

    Article  ADS  Google Scholar 

  3. Newell, P. T., Meng, C.-I. & Lyons, K. M. Suppression of discrete aurorae by sunlight. Nature 381, 766–767 (1996)

    Article  CAS  ADS  Google Scholar 

  4. Liou, K., Newell, P. T., Meng, C.-I., Brittnacher, M. & Parks, G. Seasonal effects on auroral particle acceleration and precipitation. J. Geophys. Res. 106, 5531–5542 (2001)

    Article  ADS  Google Scholar 

  5. Richmond, A. D. & Roble, R. G. Electrodynamic effects of therospheric winds from the NCAR thermospheric general circulation model. J. Geophys. Res. 92, 12365–12376 (1987)

    Article  ADS  Google Scholar 

  6. Benkevich, L., Lyatsky, W. & Cogger, L. L. Field-aligned currents between the conjugate hemispheres. J. Geophys. Res. 105, 27727–27737 (2000)

    Article  ADS  Google Scholar 

  7. Mende, S. B. et al. Far ultraviolet imaging from the IMAGE spacecraft. 2. Wideband FUV imaging. Space Sci. Rev. 91, 271–285 (2000)

    Article  CAS  ADS  Google Scholar 

  8. Frank, L. A. et al. The Visible Imaging System (VIS) for the Polar spacecraft. Space Sci. Rev. 71, 297–328 (1995)

    Article  CAS  ADS  Google Scholar 

  9. Stenbaek-Nielsen, H. C., Wescott, T. N., Davis, T. N. & Peterson, R. W. Auroral intensity differences at conjugate points. J. Geophys. Res. 78, 659–671 (1973)

    Article  ADS  Google Scholar 

  10. Fillingim, M. O., Parks, G. K., Frey, H. U., Immel, T. J. & Mende, S. B. Hemispheric asymmetry of the afternoon electron aurora. Geophys. Res. Lett. 32 L03113 10.1029/2004GL021635 (2005)

    Article  ADS  Google Scholar 

  11. Stubbs, T. J., Vondrak, R. R., Østgaard, N., Sigwarth, J. B. & Frank, L. A. Simultaneous observations of the auroral oval in both hemispheres under varying conditions. Geophys. Res. Lett. 32 L03103 10.1029/2004GL021199 (2005)

    Article  ADS  Google Scholar 

  12. Heppner, J. P. & Meynard, N. C. Empirical high-latitude electric field models. J. Geophys. Res. 92, 4467–4489 (1987)

    Article  ADS  Google Scholar 

  13. Cowley, S. W. H. Asymmetry effects associated with the X-component of the IMF in a magnettically open magnetosphere. Planet. Space Sci. 29, 809–818 (1981)

    Article  ADS  Google Scholar 

  14. Sato, N., Nagaoka, T., Hashimoto, K. & Saemundsson, T. Conjugacy of isolated auroral arcs and non-conjugate auroral break-ups. J. Geophys. Res. 103, 11641–11652 (1998)

    Article  ADS  Google Scholar 

  15. Lyatskaya, S., Lyatsky, W. & Khazanov, G. V. Relationship between substorm activity and magnetic disturbances in the two polar caps. Geophys. Res. Lett. 35 L20104 10.1029/2008GL035187 (2008)

    Article  ADS  Google Scholar 

  16. Frank, L. A. & Sigwarth, J. B. Simultaneous images of the northern and southern auroras from the Polar spacecraft: an auroral substorm. J. Geophys. Res. 108 8015 10.1029/2002JA009356 (2003)

    Article  Google Scholar 

  17. Frey, H. U. et al. Summary of quantitative interpretation of IMAGE Far Ultraviolet auroral data. Space Sci. Rev. 109, 255–283 (2003)

    Article  ADS  Google Scholar 

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We are indebted to the IMAGE and Polar teams for the design and successful operations of the two missions. We especially thank S. B. Mende for the use of IMAGE FUV WIC data and J. B. Sigwarth for the use of Polar VIS Earth Camera data. This study was supported by the Norwegian Research Council, through the IPY-ICESTAR project 176045/S30

Author Contributions N.Ø is responsible for the project planning, K.M.L. is responsible for the data processing. The data were identified and analysed by K.M.L. and N.Ø. The manuscript was written by K.M.L. and N.Ø.

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Correspondence to N. Østgaard.

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Laundal, K., Østgaard, N. Asymmetric auroral intensities in the Earth’s Northern and Southern hemispheres. Nature 460, 491–493 (2009).

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