Llif yr atmosffer drydanol dros begwn y gogledd


Llif yr atmosffer drydanol dros begwn y gogledd
(The flow of ionised atmosphere over the north pole)

S. Eleri Pryse, Helen R. Middleton and Alan G. Wood

The paper investigates the structure and behaviour of the nighttime ionised (electrified) atmosphere in the polar and auroral regions; the region where the aurora borealis occurs. Of particular interest are plasma structures on horizontal scales of hundreds of kilometres. The observations presented were made by the radiotomography experiment of the University of Wales, Aberystwyth, which has four satellite receiving systems in the high Arctic near the north pole, at Ny Ålesund and Longyearbyen on Svalbard, Bjørnøya (Bear Island) and Tromsø on mainland Norway. Comparisons of tomography images with observations of plasma flow by the international SuperDARN radar suggest that large density plasma produced on the dayside flows across the polar region and into the night sector. The results contribute to the interpretation of physical processes that couple the Earth's environment with space, and are also of interest to users of radio systems where the ionised atmosphere can degrade the propagation of the signals.


Reference:

 
  	S. Eleri Pryse, Helen R. Middleton and Alan G. Wood, 'Llif yr atmosffer drydanol dros begwn y gogledd: Arsylwadau tomograffi radio a SuperDARN', Gwerddon, 2, October 2007, 35-50.
   

Keywords

 
    Atmosphere, north pole, radiotomography, plasma, physics, space.
    

Bibliography:

 
  	
  1. Anderson, D. N., Buchau, J., a Heelis, R. A., (1988), ‘Origin of density enhancements in the winter polar cap ionosphere’, Radio Science, 23, 515–19.
  2. Bowline, M. D., Sojka, J. J., a Schunk, R. W., (1996), ‘Relationship of theoretical patch climatology to polar cap patch observations’, Radio Science, 31, 635–44.
  3. Buchau, J., Weber, E. J., Anderson, D. N., et al., (1985), ‘Ionospheric structures in the polar cap: their origin in relation to 250-MHz scintillation’, Radio Science, 20, 325–38.
  4. Cowley, S. W. H., Morelli, J. P. a Lockwood, M., (1991), ‘Dependence of convective flows and particle precipitation in the high-latitude dayside ionosphere on the X and Y components of the interplanetary magnetic field’, Journal of Geophysical Research, 96, 5557–64.
  5. Crowley, G., (1996), ‘Critical review of ionospheric patches and blobs’, Stone, W. R. (ed.), URSI Review of Radio Science 1993–96, 619–48.
  6. de la Beaujardière, O., Wickwar, V.B., Caudal, G., et al., (1985), ‘Universal time dependence of night-time F region densities at high latitudes’, Journal of Geophysical Research, 90, 4319–32.
  7. Greenwald, R. A., Baker, K. B., Dudeney, J. R., et al., (1995), ‘Darn/Superdarn: A global view of the dynamics of high-latitude convection’, Space Science Review, 71, 761–96.
  8. Hargreaves, J. K., (1992), ‘The solar-terrestrial environment’, Cambridge atmospheric and Space Science Series (Cambridge, Cambridge University Press).
  9. McEwen, D. J., a Harris, D. P., (1996), ‘Occurrence patterns of F layer patches over the north magnetic pole’, Radio Science, 31, 619–28.
  10. Middleton, H. R., Pryse, S. E., Dewis, K. L., et al., (2005), ‘Signatures of space weather processes in the northern polar ionosphere: Radio Tomography and the 50 CTIP model’, 2nd European Space Weather Week, ESWW-II, ESA-ESTEC, Noordwijk, The Netherlands, November 2005 (poster).
  11. Pryse, S. E., Wood, A. W., Middleton, H. R., et al., (2006), ‘Reconfiguration of polar-cap plasma in the magnetic midnight sector’, Annales Geophysicae, 24, 22018.
  12. Pryse, S. E., Sims, R. W., Moen, J., et al., (2004), ‘Evidence for solar-production as a source of polar-cap plasma’, Annales. Geophsyicae, 22, 1093–102.
  13. Pryse, S.E., (2003), ‘Radio tomography: A new experimental technique’, Surveys in Geophysics, 24, 1–38.
  14. Robinson, R. M., Tsunoda, R. T., a Vickrey, J. F., (1985), ‘Sources of F-region ionisation enhancements in the nighttime auroral zone’, Journal of Geophysical Research, 90, 7533–46.
  15. Rodger, A. S., Pinnock, M., Dudeney, J. R., et al., (1994), ‘A new mechanism for polar patch formation’, Journal of Geophysical Research, 99, 6425–36.
  16. Ruohoniemi, J. M., a Baker, K. B., (1998), ‘Large-scale imaging of high-latitude convection with Super Dual Auroral radar Network HF radar observations’, Journal of Geophysical Research, 103, 20797–806.
  17. Sims, R. W., Pryse, S. E., a Denig, W. F., (2005), ‘Spatial structure of summertime ionospheric plasma near magnetic noon’, Annales Geophysicae, 23, 25–37.
  18. Sojka, J. J., Bowline, M. D., Schunk, R. W., et al., (1993), ‘Modelling polar-cap F-region patches using timevarying convection’, Geophysical Research Letters, 20, 1783–6.
  19. Valladares, C. E., Basu, S., Buchau, J., et al., (1994), ‘Experimental evidence for the formation and entry of patches into the polar cap’, Radio Science, 29, 167–94.
  20. Weber, E. J., Buchau, J., Moore, J. G., et al., (1984), ‘F-layer ionization patches in the polar cap’, Journal of Geophysical Research, 89, 1683–94.