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Observations relating changes in thermospheric composition to depletions in topside ionization during the geomagnetic storm of September 1982

1984; American Geophysical Union; Volume: 89; Issue: A4 Linguagem: Inglês

10.1029/ja089ia04p02389

2156-2202

N. J. Miller, H. G. Mayr, N. W. Spencer, L. H. Brace, G. R. Carignan,

Atmospheric Ozone and Climate

Data taken over midlatitudes by Dynamics Explorer 2 during a geomagnetic storm are used to demonstrate that a direct correlation exists between depletions in the ratio [O]/[N 2 ] and in the topside electron density (N e ). That correlation is most conspicuous along 45° invariant latitude where a decrease in [O]/[N 2 ] by a factor of 5 is associated with a depletion in N e by a factor of 8. Data comparisons were made by using densities of molecular nitrogen and atomic oxygen measured by the neutral atmosphere composition spectrometer, gas temperatures measured by the wind and temperature spectrometer, and temperatures and densities of thermal electrons measured by the Langmuir probe. The measurements were taken in the sunlit northern hemisphere during September 21–23, 1982, in the altitude range 300–500 km. During the storm, gas temperatures were elevated, while the ratio [O]/[N 2 ] and N e were reduced. At 60° and 45° invariant latitudes, the most significant disturbances in the ratio [O]/[N 2 ] and N e were depletions; but at 20° invariant latitude, depletions in the ratio [O]/[N 2 ] and N e were preceded by enhancements. The correlations between variations in the ratio [O]/[N 2 ] and N e indicate that, for this storm, ion chemistry controls the observed variations of topside N e at the higher latitudes. However, the development at 20° invariant latitude of elevated gas temperatures and an enhancement in N e indicates that a storm induced equatorward wind component transported plasma toward lower latitudes at a rate that initially exceeded the rate of ionization losses there.