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Quiet and disturbed electron density profiles in the auroral zone ionosphere
Author(s) -
Bates Howard F.,
Hunsucker Robert D.
Publication year - 1974
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs009i004p00455
Subject(s) - ionosphere , incoherent scatter , electron density , f region , physics , geophysics , atmospheric sciences , latitude , geomagnetic storm , altitude (triangle) , electron , ionization , night sky , earth's magnetic field , magnetic field , ion , astronomy , geometry , mathematics , quantum mechanics
Electron density profiles of the auroral zone ionosphere for quiet, aurorally disturbed, and magnetic storm conditions have been obtained by the Chatanika incoherent scatter radar (magnetic latitude 65.7°, L = 5.7). The magnetically disturbed F region is found to be reduced somewhat in maximum density and greatly modified in shape during daylight. Field‐aligned ion transport caused by neutral winds is suggested as the cause of this behavior. The maximum density in the disturbed, dark ionosphere usually occurs in the auroral E layer, a thick layer with typical densities of 2 to 5 × 10 11 e m −3 extending for several degrees of latitude. The auroral F layer has typical maximum densities of 0.5 to 2.0 × 10 11 e m −3 at 300 to 400 km altitude; upward transport and secondary ionization by soft auroral primaries are suggested as the cause of the auroral F layer. During quiet periods between May and September, the high latitude F 1 layer exists as a well‐defined thick layer, sometimes with a distinct valley between it and the F 2 layer. In addition to high D ‐region absorption accompanying disturbances, the observed high variability of the E and F regions can explain much of the behavior of transauroral HF propagation that has been noted by past studies. This paper reviews recent incoherent scatter results with regard to their implications to high latitude HF propagation. In particular, the importance of Joule heating effects on the F ‐region atmosphere are discussed in terms of their effect on the F layer. A few clear cases of spread‐ F in the College ionograms have been found for times when the radar was observing near the ionosonde zenith. In all of the cases found, the maximum density of the layer corresponded to the inner edge of the spread trace; current scaling practice therefore appears to be correct.